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• Remove array elements that are less than X

  - by GGio

  I have arrays: $arr1 = array(5, 3, 9, 11, 6, 15); $arr2 = array(11, 20, 1, 3, 8); Now I need to loop through $arr1 and find the largest number that is less than X: foreach($arr1 as $x) { //need element that is MAX in $arr2 but is less than $x } so for example for the first run when $x = 5, maximum in $arr2 is 3 that is less than 5. Is it possible to do this without having nested loop? I do not want to loop through $arr2. I tried using array_filter but didnt really work. Maybe I used it wrong. This is what I tried with array_filter: $results = array(); foreach($arr1 as $x) { $max = max(array_filter($arr2, function ($x) { return $x < $y; })); $results[$x] = $max; } The result should be this: 5 => 3, 3 => 1, 9 => 8, 11 => 8, 6 => 3, 15 => 11

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• F# why my recursion is faster than Seq.exists?

  - by user38397

  I am pretty new to F#. I'm trying to understand how I can get a fast code in F#. For this, I tried to write two methods (IsPrime1 and IsPrime2) for benchmarking. My code is: // Learn more about F# at http://fsharp.net open System open System.Diagnostics #light let isDivisible n d = n % d = 0 let IsPrime1 n = Array.init (n-2) ((+) 2) |> Array.exists (isDivisible n) |> not let rec hasDivisor n d = match d with | x when x < n -> (n % x = 0) || (hasDivisor n (d+1)) | _ -> false let IsPrime2 n = hasDivisor n 2 |> not let SumOfPrimes max = [|2..max|] |> Array.filter IsPrime1 |> Array.sum let maxVal = 20000 let s = new Stopwatch() s.Start() let valOfSum = SumOfPrimes maxVal s.Stop() Console.WriteLine valOfSum Console.WriteLine("IsPrime1: {0}", s.ElapsedMilliseconds) ////////////////////////////////// s.Reset() s.Start() let SumOfPrimes2 max = [|2..max|] |> Array.filter IsPrime2 |> Array.sum let valOfSum2 = SumOfPrimes2 maxVal s.Stop() Console.WriteLine valOfSum2 Console.WriteLine("IsPrime2: {0}", s.ElapsedMilliseconds) Console.ReadKey() IsPrime1 takes 760 ms while IsPrime2 takes 260ms for the same result. What's going on here and how I can make my code even faster?

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• vertically aligning image in fluid container

  - by archytect

  looked for other examples but couldn't find any. my image container uses max-width/max-height so the image scales to the container but I can't seem to get it to auto margin top/bottom or vertical align it to the middle without setting a height. html, body { width: 100%; height: 100%; margin: 0px; } #container { border: solid 1px #000; height: 100%; width: 65%; position: absolute; right: 0; } #container img { max-width: 100%; max-height: 100%; display: block; margin: auto; vertical-align: middle; }? <div id="container"><img src="http://rack.2.mshcdn.com/media/ZgkyMDEyLzEyLzE2LzAzL3NjcmVlbnNob3QyXzJlb2RkLnBuZwpwCXRodW1iCTg1MHg1OTA+CmUJanBn/5b500a85/9ee/screen-shot-2012-12-14-at-9-45-01-am.jpg" /> </div>? http://jsfiddle.net/beftR/

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• I see no LOBs!

  - by Paul White

  Is it possible to see LOB (large object) logical reads from STATISTICS IO output on a table with no LOB columns? I was asked this question today by someone who had spent a good fraction of their afternoon trying to work out why this was occurring – even going so far as to re-run DBCC CHECKDB to see if any corruption had taken place.  The table in question wasn’t particularly pretty – it had grown somewhat organically over time, with new columns being added every so often as the need arose.  Nevertheless, it remained a simple structure with no LOB columns – no TEXT or IMAGE, no XML, no MAX types – nothing aside from ordinary INT, MONEY, VARCHAR, and DATETIME types.  To add to the air of mystery, not every query that ran against the table would report LOB logical reads – just sometimes – but when it did, the query often took much longer to execute. Ok, enough of the pre-amble.  I can’t reproduce the exact structure here, but the following script creates a table that will serve to demonstrate the effect: IF OBJECT_ID(N'dbo.Test', N'U') IS NOT NULL DROP TABLE dbo.Test GO CREATE TABLE dbo.Test ( row_id NUMERIC IDENTITY NOT NULL,   col01 NVARCHAR(450) NOT NULL, col02 NVARCHAR(450) NOT NULL, col03 NVARCHAR(450) NOT NULL, col04 NVARCHAR(450) NOT NULL, col05 NVARCHAR(450) NOT NULL, col06 NVARCHAR(450) NOT NULL, col07 NVARCHAR(450) NOT NULL, col08 NVARCHAR(450) NOT NULL, col09 NVARCHAR(450) NOT NULL, col10 NVARCHAR(450) NOT NULL, CONSTRAINT [PK dbo.Test row_id] PRIMARY KEY CLUSTERED (row_id) ) ; The next script loads the ten variable-length character columns with one-character strings in the first row, two-character strings in the second row, and so on down to the 450th row: WITH Numbers AS ( -- Generates numbers 1 - 450 inclusive SELECT TOP (450) n = ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2, master.sys.columns C3 ORDER BY n ASC ) INSERT dbo.Test WITH (TABLOCKX) SELECT REPLICATE(N'A', N.n), REPLICATE(N'B', N.n), REPLICATE(N'C', N.n), REPLICATE(N'D', N.n), REPLICATE(N'E', N.n), REPLICATE(N'F', N.n), REPLICATE(N'G', N.n), REPLICATE(N'H', N.n), REPLICATE(N'I', N.n), REPLICATE(N'J', N.n) FROM Numbers AS N ORDER BY N.n ASC ; Once those two scripts have run, the table contains 450 rows and 10 columns of data like this: Most of the time, when we query data from this table, we don’t see any LOB logical reads, for example: -- Find the maximum length of the data in -- column 5 for a range of rows SELECT result = MAX(DATALENGTH(T.col05)) FROM dbo.Test AS T WHERE row_id BETWEEN 50 AND 100 ; But with a different query… -- Read all the data in column 1 SELECT result = MAX(DATALENGTH(T.col01)) FROM dbo.Test AS T ; …suddenly we have 49 LOB logical reads, as well as the ‘normal’ logical reads we would expect. The Explanation If we had tried to create this table in SQL Server 2000, we would have received a warning message to say that future INSERT or UPDATE operations on the table might fail if the resulting row exceeded the in-row storage limit of 8060 bytes.  If we needed to store more data than would fit in an 8060 byte row (including internal overhead) we had to use a LOB column – TEXT, NTEXT, or IMAGE.  These special data types store the large data values in a separate structure, with just a small pointer left in the original row. Row Overflow SQL Server 2005 introduced a feature called row overflow, which allows one or more variable-length columns in a row to move to off-row storage if the data in a particular row would otherwise exceed 8060 bytes.  You no longer receive a warning when creating (or altering) a table that might need more than 8060 bytes of in-row storage; if SQL Server finds that it can no longer fit a variable-length column in a particular row, it will silently move one or more of these columns off the row into a separate allocation unit. Only variable-length columns can be moved in this way (for example the (N)VARCHAR, VARBINARY, and SQL_VARIANT types).  Fixed-length columns (like INTEGER and DATETIME for example) never move into ‘row overflow’ storage.  The decision to move a column off-row is done on a row-by-row basis – so data in a particular column might be stored in-row for some table records, and off-row for others. In general, if SQL Server finds that it needs to move a column into row-overflow storage, it moves the largest variable-length column record for that row.  Note that in the case of an UPDATE statement that results in the 8060 byte limit being exceeded, it might not be the column that grew that is moved! Sneaky LOBs Anyway, that’s all very interesting but I don’t want to get too carried away with the intricacies of row-overflow storage internals.  The point is that it is now possible to define a table with non-LOB columns that will silently exceed the old row-size limit and result in ordinary variable-length columns being moved to off-row storage.  Adding new columns to a table, expanding an existing column definition, or simply storing more data in a column than you used to – all these things can result in one or more variable-length columns being moved off the row. Note that row-overflow storage is logically quite different from old-style LOB and new-style MAX data type storage – individual variable-length columns are still limited to 8000 bytes each – you can just have more of them now.  Having said that, the physical mechanisms involved are very similar to full LOB storage – a column moved to row-overflow leaves a 24-byte pointer record in the row, and the ‘separate storage’ I have been talking about is structured very similarly to both old-style LOBs and new-style MAX types.  The disadvantages are also the same: when SQL Server needs a row-overflow column value it needs to follow the in-row pointer a navigate another chain of pages, just like retrieving a traditional LOB. And Finally… In the example script presented above, the rows with row_id values from 402 to 450 inclusive all exceed the total in-row storage limit of 8060 bytes.  A SELECT that references a column in one of those rows that has moved to off-row storage will incur one or more lob logical reads as the storage engine locates the data.  The results on your system might vary slightly depending on your settings, of course; but in my tests only column 1 in rows 402-450 moved off-row.  You might like to play around with the script – updating columns, changing data type lengths, and so on – to see the effect on lob logical reads and which columns get moved when.  You might even see row-overflow columns moving back in-row if they are updated to be smaller (hint: reduce the size of a column entry by at least 1000 bytes if you hope to see this). Be aware that SQL Server will not warn you when it moves ‘ordinary’ variable-length columns into overflow storage, and it can have dramatic effects on performance.  It makes more sense than ever to choose column data types sensibly.  If you make every column a VARCHAR(8000) or NVARCHAR(4000), and someone stores data that results in a row needing more than 8060 bytes, SQL Server might turn some of your column data into pseudo-LOBs – all without saying a word. Finally, some people make a distinction between ordinary LOBs (those that can hold up to 2GB of data) and the LOB-like structures created by row-overflow (where columns are still limited to 8000 bytes) by referring to row-overflow LOBs as SLOBs.  I find that quite appealing, but the ‘S’ stands for ‘small’, which makes expanding the whole acronym a little daft-sounding…small large objects anyone? © Paul White 2011 email: [email protected] twitter: @SQL_Kiwi

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• Resolving data redundancy up front

  - by okeofs

  Introduction As all of us do when confronted with a problem, the resource of choice is to ‘Google it’. This is where the plot thickens. Recently I was asked to stage data from numerous databases which were to be loaded into a data warehouse. To make a long story short, I was looking for a manner in which to obtain the table names from each database, to ascertain potential overlap.   As the source data comes from a SQL database created from dumps of a third party product,  one could say that there were +/- 95 tables for each database.   Yes I know that first instinct is to use the system stored procedure “exec sp_msforeachdb 'select "?" AS db, * from [?].sys.tables'”. However, if one stops to think about this, it would be nice to have all the results in a temporary or disc based  table; which in itself , implies additional labour. This said,  I decided to ‘re-invent’ the wheel. The full code sample may be found at the bottom of this article.   Define a few temporary tables and variables   declare @SQL varchar(max); declare @databasename varchar(75) /* drop table ##rawdata3 drop table #rawdata1 drop table #rawdata11 */ -- A temp table to hold the names of my databases CREATE TABLE #rawdata1 (    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) )     --A temp table with the same database names as above, HOWEVER using an --Identity number (recNO) as a loop variable. --You will note below that I loop through until I reach 25 (see below) as at --that point the system databases, the reporting server database etc begin. --1- 24 are user databases. These are really what I was looking for. --Whilst NOT the best solution,it works and the code was meant as a quick --and dirty. CREATE TABLE #rawdata11 (    recNo int identity(1,1),    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) )   --My output table showing the database name and table name CREATE TABLE ##rawdata3 (    database_name varchar(75) ,    table_name varchar(75), )   Insert the database names into a temporary table I pull the database names using the system stored procedure sp_databases   INSERT INTO #rawdata1 EXEC sp_databases Go   Insert the results from #rawdata1 into a table containing a record number  #rawdata11 so that I can LOOP through the extract   INSERT into #rawdata11 select * from  #rawdata1   We now declare 3 more variables:  @kounter is used to keep track of our position within the loop. @databasename is used to keep track of the’ current ‘ database name being used in the current pass of the loop;  as inorder to obtain the tables for that database we  need to issue a ‘USE’ statement, an insert command and other related code parts. This is the challenging part. @sql is a varchar(max) variable used to contain the ‘USE’ statement PLUS the’ insert ‘ code statements. We now initalize @kounter to 1 .   declare @kounter int; declare @databasename varchar(75); declare @sql varchar(max); set @kounter = 1   The Loop The astute reader will remember that the temporary table #rawdata11 contains our  database names  and each ‘database row’ has a record number (recNo). I am only interested in record numbers under 25. I now set the value of the temporary variable @DatabaseName (see below) .Note that I used the row number as a part of the predicate. Now, knowing the database name, I can create dynamic T-SQL to be executed using the sp_sqlexec stored procedure (see the code in red below). Finally, after all the tables for that given database have been placed in temporary table ##rawdata3, I increment the counter and continue on. Note that I used a global temporary table to ensure that the result set persists after the termination of the run. At some stage, I plan to redo this part of the code, as global temporary tables are not really an ideal solution.    WHILE (@kounter < 25)  BEGIN  select @DatabaseName = database_name from #rawdata11 where recNo = @kounter  set @SQL = 'Use ' + @DatabaseName + ' Insert into ##rawdata3 ' + + ' SELECT table_catalog,Table_name FROM information_schema.tables' exec sp_sqlexec  @Sql  SET @kounter  = @kounter + 1  END   The full code extract   Here is the full code sample.   declare @SQL varchar(max); declare @databasename varchar(75) /* drop table ##rawdata3 drop table #rawdata1 drop table #rawdata11 */ CREATE TABLE #rawdata1 (    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) ) CREATE TABLE #rawdata11 (    recNo int identity(1,1),    database_name varchar(50) ,    database_size varchar(50),    remarks Varchar(50) ) CREATE TABLE ##rawdata3 (    database_name varchar(75) ,    table_name varchar(75), )   INSERT INTO #rawdata1 EXEC sp_databases go INSERT into #rawdata11 select * from  #rawdata1 declare @kounter int; declare @databasename varchar(75); declare @sql varchar(max); set @kounter = 1 WHILE (@kounter < 25)  BEGIN  select @databasename = database_name from #rawdata11 where recNo = @kounter  set @SQL = 'Use ' + @DatabaseName + ' Insert into ##rawdata3 ' + + ' SELECT table_catalog,Table_name FROM information_schema.tables' exec sp_sqlexec  @Sql  SET @kounter  = @kounter + 1  END    select * from ##rawdata3  where table_name like '%SalesOrderHeader%'

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• Data Guard - Snapshot Standby Database??

  - by Jian Zhang-Oracle

  ?? -------- ?????,??standby?????mount??????????REDO??,??standby????????????????????,???????read-only???open????,????ACTIVE DATA GUARD,????standby?????????(read-only)??(????????),????standby???????????(read-write)? ?????,?????????????Real Application Testing(RAT)??????????,?????????standby??????snapshot standby?????????,??snapshot standby??????????,???????????(read-write)??????snapshot standby??????????????,?????????,??????????,????????,?????????snapshot standby?????standby???,????????? ?? ---------  1.??standby?????? SQL> Alter system set db_recovery_file_dest_size=500M; System altered. SQL> Alter system set db_recovery_file_dest='/u01/app/oracle/snapshot_standby'; System altered. 2.??standby?????? SQL> alter database recover managed standby database cancel; Database altered. 3.??standby???snapshot standby,??open snapshot standby SQL> alter database convert to snapshot standby; Database altered. SQL> alter database open;    Database altered. ??snapshot standby??????SNAPSHOT STANDBY,open???READ WRITE: SQL> select DATABASE_ROLE,name,OPEN_MODE from v$database; DATABASE_ROLE    NAME      OPEN_MODE ---------------- --------- -------------------- SNAPSHOT STANDBY FSDB      READ WRITE 4.?snapshot standby???????????Real Application Testing(RAT)????????? 5.?????,??snapshot standby???physical standby,?????????? SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> startup mount; ORACLE instance started. Database mounted. SQL> ALTER DATABASE CONVERT TO PHYSICAL STANDBY; Database altered. SQL> shutdown immediate; ORA-01507: database not mounted ORACLE instance shut down. SQL> startup mount; ORACLE instance started. Database mounted. SQL>ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION; Database altered. 5.?????standby?,???????PHYSICAL STANDBY,open???MOUNTED SQL> select DATABASE_ROLE,name,OPEN_MODE from v$database; DATABASE_ROLE    NAME      OPEN_MODE ---------------- --------- -------------------- PHYSICAL STANDBY FSDB      MOUNTED 6.??????????????? ????: SQL> select ads.dest_id,max(sequence#) "Current Sequence",            max(log_sequence) "Last Archived"        from v$archived_log al, v$archive_dest ad, v$archive_dest_status ads        where ad.dest_id=al.dest_id        and al.dest_id=ads.dest_id        and al.resetlogs_change#=(select max(resetlogs_change#) from v$archived_log )        group by ads.dest_id;    DEST_ID Current Sequence Last Archived ---------- ---------------- -------------      1              361           361      2              361           362 --???? SQL>    select al.thrd "Thread", almax "Last Seq Received", lhmax "Last Seq Applied"       from (select thread# thrd, max(sequence#) almax           from v$archived_log           where resetlogs_change#=(select resetlogs_change# from v$database)           group by thread#) al,          (select thread# thrd, max(sequence#) lhmax           from v$log_history           where resetlogs_change#=(select resetlogs_change# from v$database)           group by thread#) lh      where al.thrd = lh.thrd;     Thread Last Seq Received Last Seq Applied ---------- ----------------- ----------------          1               361              361 ??????????,???blog,???????????,??"??:Data Guard - Snapshot Standby Database??" 

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• Beware Sneaky Reads with Unique Indexes

  - by Paul White NZ

  A few days ago, Sandra Mueller (twitter | blog) asked a question using twitter’s #sqlhelp hash tag: “Might SQL Server retrieve (out-of-row) LOB data from a table, even if the column isn’t referenced in the query?” Leaving aside trivial cases (like selecting a computed column that does reference the LOB data), one might be tempted to say that no, SQL Server does not read data you haven’t asked for.  In general, that’s quite correct; however there are cases where SQL Server might sneakily retrieve a LOB column… Example Table Here’s a T-SQL script to create that table and populate it with 1,000 rows: CREATE TABLE dbo.LOBtest ( pk INTEGER IDENTITY NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( some_value, lob_data ) SELECT TOP (1000) N.n, @Data FROM Numbers N WHERE N.n <= 1000; Test 1: A Simple Update Let’s run a query to subtract one from every value in the some_value column: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; As you might expect, modifying this integer column in 1,000 rows doesn’t take very long, or use many resources.  The STATITICS IO and TIME output shows a total of 9 logical reads, and 25ms elapsed time.  The query plan is also very simple: Looking at the Clustered Index Scan, we can see that SQL Server only retrieves the pk and some_value columns during the scan: The pk column is needed by the Clustered Index Update operator to uniquely identify the row that is being changed.  The some_value column is used by the Compute Scalar to calculate the new value.  (In case you are wondering what the Top operator is for, it is used to enforce SET ROWCOUNT). Test 2: Simple Update with an Index Now let’s create a nonclustered index keyed on the some_value column, with lob_data as an included column: CREATE NONCLUSTERED INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); This is not a useful index for our simple update query; imagine that someone else created it for a different purpose.  Let’s run our update query again: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; We find that it now requires 4,014 logical reads and the elapsed query time has increased to around 100ms.  The extra logical reads (4 per row) are an expected consequence of maintaining the nonclustered index. The query plan is very similar to before (click to enlarge): The Clustered Index Update operator picks up the extra work of maintaining the nonclustered index. The new Compute Scalar operators detect whether the value in the some_value column has actually been changed by the update.  SQL Server may be able to skip maintaining the nonclustered index if the value hasn’t changed (see my previous post on non-updating updates for details).  Our simple query does change the value of some_data in every row, so this optimization doesn’t add any value in this specific case. The output list of columns from the Clustered Index Scan hasn’t changed from the one shown previously: SQL Server still just reads the pk and some_data columns.  Cool. Overall then, adding the nonclustered index hasn’t had any startling effects, and the LOB column data still isn’t being read from the table.  Let’s see what happens if we make the nonclustered index unique. Test 3: Simple Update with a Unique Index Here’s the script to create a new unique index, and drop the old one: CREATE UNIQUE NONCLUSTERED INDEX [UQ dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); GO DROP INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest; Remember that SQL Server only enforces uniqueness on index keys (the some_data column).  The lob_data column is simply stored at the leaf-level of the non-clustered index.  With that in mind, we might expect this change to make very little difference.  Let’s see: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; Whoa!  Now look at the elapsed time and logical reads: Scan count 1, logical reads 2016, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   CPU time = 172 ms, elapsed time = 16172 ms. Even with all the data and index pages in memory, the query took over 16 seconds to update just 1,000 rows, performing over 52,000 LOB logical reads (nearly 16,000 of those using read-ahead). Why on earth is SQL Server reading LOB data in a query that only updates a single integer column? The Query Plan The query plan for test 3 looks a bit more complex than before: In fact, the bottom level is exactly the same as we saw with the non-unique index.  The top level has heaps of new stuff though, which I’ll come to in a moment. You might be expecting to find that the Clustered Index Scan is now reading the lob_data column (for some reason).  After all, we need to explain where all the LOB logical reads are coming from.  Sadly, when we look at the properties of the Clustered Index Scan, we see exactly the same as before: SQL Server is still only reading the pk and some_value columns – so what’s doing the LOB reads? Updates that Sneakily Read Data We have to go as far as the Clustered Index Update operator before we see LOB data in the output list: [Expr1020] is a bit flag added by an earlier Compute Scalar.  It is set true if the some_value column has not been changed (part of the non-updating updates optimization I mentioned earlier). The Clustered Index Update operator adds two new columns: the lob_data column, and some_value_OLD.  The some_value_OLD column, as the name suggests, is the pre-update value of the some_value column.  At this point, the clustered index has already been updated with the new value, but we haven’t touched the nonclustered index yet. An interesting observation here is that the Clustered Index Update operator can read a column into the data flow as part of its update operation.  SQL Server could have read the LOB data as part of the initial Clustered Index Scan, but that would mean carrying the data through all the operations that occur prior to the Clustered Index Update.  The server knows it will have to go back to the clustered index row to update it, so it delays reading the LOB data until then.  Sneaky! Why the LOB Data Is Needed This is all very interesting (I hope), but why is SQL Server reading the LOB data?  For that matter, why does it need to pass the pre-update value of the some_value column out of the Clustered Index Update? The answer relates to the top row of the query plan for test 3.  I’ll reproduce it here for convenience: Notice that this is a wide (per-index) update plan.  SQL Server used a narrow (per-row) update plan in test 2, where the Clustered Index Update took care of maintaining the nonclustered index too.  I’ll talk more about this difference shortly. The Split/Sort/Collapse combination is an optimization, which aims to make per-index update plans more efficient.  It does this by breaking each update into a delete/insert pair, reordering the operations, removing any redundant operations, and finally applying the net effect of all the changes to the nonclustered index. Imagine we had a unique index which currently holds three rows with the values 1, 2, and 3.  If we run a query that adds 1 to each row value, we would end up with values 2, 3, and 4.  The net effect of all the changes is the same as if we simply deleted the value 1, and added a new value 4. By applying net changes, SQL Server can also avoid false unique-key violations.  If we tried to immediately update the value 1 to a 2, it would conflict with the existing value 2 (which would soon be updated to 3 of course) and the query would fail.  You might argue that SQL Server could avoid the uniqueness violation by starting with the highest value (3) and working down.  That’s fine, but it’s not possible to generalize this logic to work with every possible update query. SQL Server has to use a wide update plan if it sees any risk of false uniqueness violations.  It’s worth noting that the logic SQL Server uses to detect whether these violations are possible has definite limits.  As a result, you will often receive a wide update plan, even when you can see that no violations are possible. Another benefit of this optimization is that it includes a sort on the index key as part of its work.  Processing the index changes in index key order promotes sequential I/O against the nonclustered index. A side-effect of all this is that the net changes might include one or more inserts.  In order to insert a new row in the index, SQL Server obviously needs all the columns – the key column and the included LOB column.  This is the reason SQL Server reads the LOB data as part of the Clustered Index Update. In addition, the some_value_OLD column is required by the Split operator (it turns updates into delete/insert pairs).  In order to generate the correct index key delete operation, it needs the old key value. The irony is that in this case the Split/Sort/Collapse optimization is anything but.  Reading all that LOB data is extremely expensive, so it is sad that the current version of SQL Server has no way to avoid it. Finally, for completeness, I should mention that the Filter operator is there to filter out the non-updating updates. Beating the Set-Based Update with a Cursor One situation where SQL Server can see that false unique-key violations aren’t possible is where it can guarantee that only one row is being updated.  Armed with this knowledge, we can write a cursor (or the WHILE-loop equivalent) that updates one row at a time, and so avoids reading the LOB data: SET NOCOUNT ON; SET STATISTICS XML, IO, TIME OFF;   DECLARE @PK INTEGER, @StartTime DATETIME; SET @StartTime = GETUTCDATE();   DECLARE curUpdate CURSOR LOCAL FORWARD_ONLY KEYSET SCROLL_LOCKS FOR SELECT L.pk FROM LOBtest L ORDER BY L.pk ASC;   OPEN curUpdate;   WHILE (1 = 1) BEGIN FETCH NEXT FROM curUpdate INTO @PK;   IF @@FETCH_STATUS = -1 BREAK; IF @@FETCH_STATUS = -2 CONTINUE;   UPDATE dbo.LOBtest SET some_value = some_value - 1 WHERE CURRENT OF curUpdate; END;   CLOSE curUpdate; DEALLOCATE curUpdate;   SELECT DATEDIFF(MILLISECOND, @StartTime, GETUTCDATE()); That completes the update in 1280 milliseconds (remember test 3 took over 16 seconds!) I used the WHERE CURRENT OF syntax there and a KEYSET cursor, just for the fun of it.  One could just as well use a WHERE clause that specified the primary key value instead. Clustered Indexes A clustered index is the ultimate index with included columns: all non-key columns are included columns in a clustered index.  Let’s re-create the test table and data with an updatable primary key, and without any non-clustered indexes: IF OBJECT_ID(N'dbo.LOBtest', N'U') IS NOT NULL DROP TABLE dbo.LOBtest; GO CREATE TABLE dbo.LOBtest ( pk INTEGER NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( pk, some_value, lob_data ) SELECT TOP (1000) N.n, N.n, @Data FROM Numbers N WHERE N.n <= 1000; Now here’s a query to modify the cluster keys: UPDATE dbo.LOBtest SET pk = pk + 1; The query plan is: As you can see, the Split/Sort/Collapse optimization is present, and we also gain an Eager Table Spool, for Halloween protection.  In addition, SQL Server now has no choice but to read the LOB data in the Clustered Index Scan: The performance is not great, as you might expect (even though there is no non-clustered index to maintain): Table 'LOBtest'. Scan count 1, logical reads 2011, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   Table 'Worktable'. Scan count 1, logical reads 2040, physical reads 0, read-ahead reads 0, lob logical reads 34000, lob physical reads 0, lob read-ahead reads 8000.   SQL Server Execution Times: CPU time = 483 ms, elapsed time = 17884 ms. Notice how the LOB data is read twice: once from the Clustered Index Scan, and again from the work table in tempdb used by the Eager Spool. If you try the same test with a non-unique clustered index (rather than a primary key), you’ll get a much more efficient plan that just passes the cluster key (including uniqueifier) around (no LOB data or other non-key columns): A unique non-clustered index (on a heap) works well too: Both those queries complete in a few tens of milliseconds, with no LOB reads, and just a few thousand logical reads.  (In fact the heap is rather more efficient). There are lots more fun combinations to try that I don’t have space for here. Final Thoughts The behaviour shown in this post is not limited to LOB data by any means.  If the conditions are met, any unique index that has included columns can produce similar behaviour – something to bear in mind when adding large INCLUDE columns to achieve covering queries, perhaps. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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• Metro: Understanding CSS Media Queries

  - by Stephen.Walther

  If you are building a Metro style application then your application needs to look great when used on a wide variety of devices. Your application needs to work on tiny little phones, slates, desktop monitors, and the super high resolution displays of the future. Your application also must support portable devices used with different orientations. If someone tilts their phone from portrait to landscape mode then your application must still be usable. Finally, your Metro style application must look great in different states. For example, your Metro application can be in a “snapped state” when it is shrunk so it can share screen real estate with another application. In this blog post, you learn how to use Cascading Style Sheet media queries to support different devices, different device orientations, and different application states. First, you are provided with an overview of the W3C Media Query recommendation and you learn how to detect standard media features. Next, you learn about the Microsoft extensions to media queries which are supported in Metro style applications. For example, you learn how to use the –ms-view-state feature to detect whether an application is in a “snapped state” or “fill state”. Finally, you learn how to programmatically detect the features of a device and the state of an application. You learn how to use the msMatchMedia() method to execute a media query with JavaScript. Using CSS Media Queries Media queries enable you to apply different styles depending on the features of a device. Media queries are not only supported by Metro style applications, most modern web browsers now support media queries including Google Chrome 4+, Mozilla Firefox 3.5+, Apple Safari 4+, and Microsoft Internet Explorer 9+. Loading Different Style Sheets with Media Queries Imagine, for example, that you want to display different content depending on the horizontal resolution of a device. In that case, you can load different style sheets optimized for different sized devices. Consider the following HTML page: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>U.S. Robotics and Mechanical Men</title> <link href="main.css" rel="stylesheet" type="text/css" /> <!-- Less than 1100px --> <link href="medium.css" rel="stylesheet" type="text/css" media="(max-width:1100px)" /> <!-- Less than 800px --> <link href="small.css" rel="stylesheet" type="text/css" media="(max-width:800px)" /> </head> <body> <div id="header"> <h1>U.S. Robotics and Mechanical Men</h1> </div> <!-- Advertisement Column --> <div id="leftColumn"> <img src="advertisement1.gif" alt="advertisement" /> <img src="advertisement2.jpg" alt="advertisement" /> </div> <!-- Product Search Form --> <div id="mainContentColumn"> <label>Search Products</label> <input id="search" /><button>Search</button> </div> <!-- Deal of the Day Column --> <div id="rightColumn"> <h1>Deal of the Day!</h1> <p> Buy two cameras and get a third camera for free! Offer is good for today only. </p> </div> </body> </html> The HTML page above contains three columns: a leftColumn, mainContentColumn, and rightColumn. When the page is displayed on a low resolution device, such as a phone, only the mainContentColumn appears: When the page is displayed in a medium resolution device, such as a slate, both the leftColumn and the mainContentColumns are displayed: Finally, when the page is displayed in a high-resolution device, such as a computer monitor, all three columns are displayed: Different content is displayed with the help of media queries. The page above contains three style sheet links. Two of the style links include a media attribute: <link href="main.css" rel="stylesheet" type="text/css" /> <!-- Less than 1100px --> <link href="medium.css" rel="stylesheet" type="text/css" media="(max-width:1100px)" /> <!-- Less than 800px --> <link href="small.css" rel="stylesheet" type="text/css" media="(max-width:800px)" /> The main.css style sheet contains default styles for the elements in the page. The medium.css style sheet is applied when the page width is less than 1100px. This style sheet hides the rightColumn and changes the page background color to lime: html { background-color: lime; } #rightColumn { display:none; } Finally, the small.css style sheet is loaded when the page width is less than 800px. This style sheet hides the leftColumn and changes the page background color to red: html { background-color: red; } #leftColumn { display:none; } The different style sheets are applied as you stretch and contract your browser window. You don’t need to refresh the page after changing the size of the page for a media query to be applied: Using the @media Rule You don’t need to divide your styles into separate files to take advantage of media queries. You can group styles by using the @media rule. For example, the following HTML page contains one set of styles which are applied when a device’s orientation is portrait and another set of styles when a device’s orientation is landscape: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>Application1</title> <style type="text/css"> html { font-family:'Segoe UI Semilight'; font-size: xx-large; } @media screen and (orientation:landscape) { html { background-color: lime; } p.content { width: 50%; margin: auto; } } @media screen and (orientation:portrait) { html { background-color: red; } p.content { width: 90%; margin: auto; } } </style> </head> <body> <p class="content"> Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue massa. Fusce posuere, magna sed pulvinar ultricies, purus lectus malesuada libero, sit amet commodo magna eros quis urna. </p> </body> </html> When a device has a landscape orientation then the background color is set to the color lime and the text only takes up 50% of the available horizontal space: When the device has a portrait orientation then the background color is red and the text takes up 90% of the available horizontal space: Using Standard CSS Media Features The official list of standard media features is contained in the W3C CSS Media Query recommendation located here: http://www.w3.org/TR/css3-mediaqueries/ Here is the official list of the 13 media features described in the standard: · width – The current width of the viewport · height – The current height of the viewport · device-width – The width of the device · device-height – The height of the device · orientation – The value portrait or landscape · aspect-ratio – The ratio of width to height · device-aspect-ratio – The ratio of device width to device height · color – The number of bits per color supported by the device · color-index – The number of colors in the color lookup table of the device · monochrome – The number of bits in the monochrome frame buffer · resolution – The density of the pixels supported by the device · scan – The values progressive or interlace (used for TVs) · grid – The values 0 or 1 which indicate whether the device supports a grid or a bitmap Many of the media features in the list above support the min- and max- prefix. For example, you can test for the min-width using a query like this: (min-width:800px) You can use the logical and operator with media queries when you need to check whether a device supports more than one feature. For example, the following query returns true only when the width of the device is between 800 and 1,200 pixels: (min-width:800px) and (max-width:1200px) Finally, you can use the different media types – all, braille, embossed, handheld, print, projection, screen, speech, tty, tv — with a media query. For example, the following media query only applies to a page when a page is being printed in color: print and (color) If you don’t specify a media type then media type all is assumed. Using Metro Style Media Features Microsoft has extended the standard list of media features which you can include in a media query with two custom media features: · -ms-high-contrast – The values any, black-white, white-black · -ms-view-state – The values full-screen, fill, snapped, device-portrait You can take advantage of the –ms-high-contrast media feature to make your web application more accessible to individuals with disabilities. In high contrast mode, you should make your application easier to use for individuals with vision disabilities. The –ms-view-state media feature enables you to detect the state of an application. For example, when an application is snapped, the application only occupies part of the available screen real estate. The snapped application appears on the left or right side of the screen and the rest of the screen real estate is dominated by the fill application (Metro style applications can only be snapped on devices with a horizontal resolution of greater than 1,366 pixels). Here is a page which contains style rules for an application in both a snap and fill application state: <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>MyWinWebApp</title> <style type="text/css"> html { font-family:'Segoe UI Semilight'; font-size: xx-large; } @media screen and (-ms-view-state:snapped) { html { background-color: lime; } } @media screen and (-ms-view-state:fill) { html { background-color: red; } } </style> </head> <body> <p class="content"> Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Maecenas porttitor congue massa. Fusce posuere, magna sed pulvinar ultricies, purus lectus malesuada libero, sit amet commodo magna eros quis urna. </p> </body> </html> When the application is snapped, the application appears with a lime background color: When the application state is fill then the background color changes to red: When the application takes up the entire screen real estate – it is not in snapped or fill state – then no special style rules apply and the application appears with a white background color. Querying Media Features with JavaScript You can perform media queries using JavaScript by taking advantage of the window.msMatchMedia() method. This method returns a MSMediaQueryList which has a matches method that represents success or failure. For example, the following code checks whether the current device is in portrait mode: if (window.msMatchMedia("(orientation:portrait)").matches) { console.log("portrait"); } else { console.log("landscape"); } If the matches property returns true, then the device is in portrait mode and the message “portrait” is written to the Visual Studio JavaScript Console window. Otherwise, the message “landscape” is written to the JavaScript Console window. You can create an event listener which triggers code whenever the results of a media query changes. For example, the following code writes a message to the JavaScript Console whenever the current device is switched into or out of Portrait mode: window.msMatchMedia("(orientation:portrait)").addListener(function (mql) { if (mql.matches) { console.log("Switched to portrait"); } }); Be aware that the event listener is triggered whenever the result of the media query changes. So the event listener is triggered both when you switch from landscape to portrait and when you switch from portrait to landscape. For this reason, you need to verify that the matches property has the value true before writing the message. Summary The goal of this blog entry was to explain how CSS media queries work in the context of a Metro style application written with JavaScript. First, you were provided with an overview of the W3C CSS Media Query recommendation. You learned about the standard media features which you can query such as width and orientation. Next, we focused on the Microsoft extensions to media queries. You learned how to use –ms-view-state to detect whether a Metro style application is in “snapped” or “fill” state. You also learned how to use the msMatchMedia() method to perform a media query from JavaScript.

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• Wireless card power management

  - by penner

  I have noticed that when my computer in plugged in, the wireless strength increases. I'm assuming this is to do with power management. Is there a way to disable Wireless Power Management? I have found a few blog posts that show hacks to disable this but what is best practice here? Should there not be an option via the power menu that lets you toggle this? EDIT -- FILES AND LOGS AS REQUESTED /var/log/kern.log Jul 11 11:45:27 CoolBreeze kernel: [ 6.528052] postgres (1308): /proc/1308/oom_adj is deprecated, please use /proc/1308/oom_score_adj instead. Jul 11 11:45:27 CoolBreeze kernel: [ 6.532080] [fglrx] Gart USWC size:1280 M. Jul 11 11:45:27 CoolBreeze kernel: [ 6.532084] [fglrx] Gart cacheable size:508 M. Jul 11 11:45:27 CoolBreeze kernel: [ 6.532091] [fglrx] Reserved FB block: Shared offset:0, size:1000000 Jul 11 11:45:27 CoolBreeze kernel: [ 6.532094] [fglrx] Reserved FB block: Unshared offset:f8fd000, size:403000 Jul 11 11:45:27 CoolBreeze kernel: [ 6.532098] [fglrx] Reserved FB block: Unshared offset:3fff4000, size:c000 Jul 11 11:45:38 CoolBreeze kernel: [ 17.423743] eth1: no IPv6 routers present Jul 11 11:46:37 CoolBreeze kernel: [ 75.836426] warning: `proftpd' uses 32-bit capabilities (legacy support in use) Jul 11 11:46:37 CoolBreeze kernel: [ 75.884215] init: plymouth-stop pre-start process (2922) terminated with status 1 Jul 11 11:54:25 CoolBreeze kernel: [ 543.679614] eth1: no IPv6 routers present dmesg [ 1.411959] ACPI: Power Button [PWRB] [ 1.412046] input: Sleep Button as /devices/LNXSYSTM:00/device:00/PNP0C0E:00/input/input1 [ 1.412054] ACPI: Sleep Button [SLPB] [ 1.412150] input: Lid Switch as /devices/LNXSYSTM:00/device:00/PNP0C0D:00/input/input2 [ 1.412765] ACPI: Lid Switch [LID0] [ 1.412866] input: Power Button as /devices/LNXSYSTM:00/LNXPWRBN:00/input/input3 [ 1.412874] ACPI: Power Button [PWRF] [ 1.412996] ACPI: Fan [FAN0] (off) [ 1.413068] ACPI: Fan [FAN1] (off) [ 1.419493] thermal LNXTHERM:00: registered as thermal_zone0 [ 1.419498] ACPI: Thermal Zone [TZ00] (27 C) [ 1.421913] thermal LNXTHERM:01: registered as thermal_zone1 [ 1.421918] ACPI: Thermal Zone [TZ01] (61 C) [ 1.421971] ACPI: Deprecated procfs I/F for battery is loaded, please retry with CONFIG_ACPI_PROCFS_POWER cleared [ 1.421986] ACPI: Battery Slot [BAT0] (battery present) [ 1.422062] ERST: Table is not found! [ 1.422067] GHES: HEST is not enabled! [ 1.422158] isapnp: Scanning for PnP cards... [ 1.422242] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled [ 1.434620] ACPI: Battery Slot [BAT0] (battery present) [ 1.736355] Freeing initrd memory: 14352k freed [ 1.777846] isapnp: No Plug & Play device found [ 1.963650] Linux agpgart interface v0.103 [ 1.967148] brd: module loaded [ 1.968866] loop: module loaded [ 1.969134] ahci 0000:00:1f.2: version 3.0 [ 1.969154] ahci 0000:00:1f.2: PCI INT B -> GSI 19 (level, low) -> IRQ 19 [ 1.969226] ahci 0000:00:1f.2: irq 45 for MSI/MSI-X [ 1.969277] ahci: SSS flag set, parallel bus scan disabled [ 1.969320] ahci 0000:00:1f.2: AHCI 0001.0300 32 slots 6 ports 3 Gbps 0x23 impl SATA mode [ 1.969329] ahci 0000:00:1f.2: flags: 64bit ncq sntf stag pm led clo pio slum part ems sxs apst [ 1.969338] ahci 0000:00:1f.2: setting latency timer to 64 [ 1.983340] scsi0 : ahci [ 1.983515] scsi1 : ahci [ 1.983670] scsi2 : ahci [ 1.983829] scsi3 : ahci [ 1.983985] scsi4 : ahci [ 1.984145] scsi5 : ahci [ 1.984270] ata1: SATA max UDMA/133 abar m2048@0xf1005000 port 0xf1005100 irq 45 [ 1.984277] ata2: SATA max UDMA/133 abar m2048@0xf1005000 port 0xf1005180 irq 45 [ 1.984282] ata3: DUMMY [ 1.984285] ata4: DUMMY [ 1.984288] ata5: DUMMY [ 1.984292] ata6: SATA max UDMA/133 abar m2048@0xf1005000 port 0xf1005380 irq 45 [ 1.985150] Fixed MDIO Bus: probed [ 1.985192] tun: Universal TUN/TAP device driver, 1.6 [ 1.985196] tun: (C) 1999-2004 Max Krasnyansky <[email protected]> [ 1.985285] PPP generic driver version 2.4.2 [ 1.985472] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver [ 1.985507] ehci_hcd 0000:00:1a.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 [ 1.985534] ehci_hcd 0000:00:1a.0: setting latency timer to 64 [ 1.985541] ehci_hcd 0000:00:1a.0: EHCI Host Controller [ 1.985626] ehci_hcd 0000:00:1a.0: new USB bus registered, assigned bus number 1 [ 1.985666] ehci_hcd 0000:00:1a.0: debug port 2 [ 1.989663] ehci_hcd 0000:00:1a.0: cache line size of 64 is not supported [ 1.989690] ehci_hcd 0000:00:1a.0: irq 16, io mem 0xf1005800 [ 2.002183] ehci_hcd 0000:00:1a.0: USB 2.0 started, EHCI 1.00 [ 2.002447] hub 1-0:1.0: USB hub found [ 2.002455] hub 1-0:1.0: 3 ports detected [ 2.002607] ehci_hcd 0000:00:1d.0: PCI INT A -> GSI 23 (level, low) -> IRQ 23 [ 2.002633] ehci_hcd 0000:00:1d.0: setting latency timer to 64 [ 2.002639] ehci_hcd 0000:00:1d.0: EHCI Host Controller [ 2.002737] ehci_hcd 0000:00:1d.0: new USB bus registered, assigned bus number 2 [ 2.002775] ehci_hcd 0000:00:1d.0: debug port 2 [ 2.006780] ehci_hcd 0000:00:1d.0: cache line size of 64 is not supported [ 2.006806] ehci_hcd 0000:00:1d.0: irq 23, io mem 0xf1005c00 [ 2.022161] ehci_hcd 0000:00:1d.0: USB 2.0 started, EHCI 1.00 [ 2.022401] hub 2-0:1.0: USB hub found [ 2.022409] hub 2-0:1.0: 3 ports detected [ 2.022567] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver [ 2.022599] uhci_hcd: USB Universal Host Controller Interface driver [ 2.022720] usbcore: registered new interface driver libusual [ 2.022813] i8042: PNP: PS/2 Controller [PNP0303:PS2K,PNP0f13:PS2M] at 0x60,0x64 irq 1,12 [ 2.035831] serio: i8042 KBD port at 0x60,0x64 irq 1 [ 2.035844] serio: i8042 AUX port at 0x60,0x64 irq 12 [ 2.036096] mousedev: PS/2 mouse device common for all mice [ 2.036710] rtc_cmos 00:07: RTC can wake from S4 [ 2.036881] rtc_cmos 00:07: rtc core: registered rtc_cmos as rtc0 [ 2.037143] rtc0: alarms up to one month, y3k, 242 bytes nvram, hpet irqs [ 2.037503] device-mapper: uevent: version 1.0.3 [ 2.037656] device-mapper: ioctl: 4.22.0-ioctl (2011-10-19) initialised: [email protected] [ 2.037725] EISA: Probing bus 0 at eisa.0 [ 2.037729] EISA: Cannot allocate resource for mainboard [ 2.037734] Cannot allocate resource for EISA slot 1 [ 2.037738] Cannot allocate resource for EISA slot 2 [ 2.037741] Cannot allocate resource for EISA slot 3 [ 2.037745] Cannot allocate resource for EISA slot 4 [ 2.037749] Cannot allocate resource for EISA slot 5 [ 2.037753] Cannot allocate resource for EISA slot 6 [ 2.037756] Cannot allocate resource for EISA slot 7 [ 2.037760] Cannot allocate resource for EISA slot 8 [ 2.037764] EISA: Detected 0 cards. [ 2.037782] cpufreq-nforce2: No nForce2 chipset. [ 2.038264] cpuidle: using governor ladder [ 2.039015] cpuidle: using governor menu [ 2.039019] EFI Variables Facility v0.08 2004-May-17 [ 2.040061] TCP cubic registered [ 2.041438] NET: Registered protocol family 10 [ 2.043814] NET: Registered protocol family 17 [ 2.043823] Registering the dns_resolver key type [ 2.044290] input: AT Translated Set 2 keyboard as /devices/platform/i8042/serio0/input/input4 [ 2.044336] Using IPI No-Shortcut mode [ 2.045620] PM: Hibernation image not present or could not be loaded. [ 2.045644] registered taskstats version 1 [ 2.073070] Magic number: 4:976:796 [ 2.073415] rtc_cmos 00:07: setting system clock to 2012-07-11 18:45:23 UTC (1342032323) [ 2.076654] BIOS EDD facility v0.16 2004-Jun-25, 0 devices found [ 2.076658] EDD information not available. [ 2.302111] ata1: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [ 2.302587] ata1.00: ATA-9: M4-CT128M4SSD2, 000F, max UDMA/100 [ 2.302595] ata1.00: 250069680 sectors, multi 16: LBA48 NCQ (depth 31/32), AA [ 2.303143] ata1.00: configured for UDMA/100 [ 2.303453] scsi 0:0:0:0: Direct-Access ATA M4-CT128M4SSD2 000F PQ: 0 ANSI: 5 [ 2.303746] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 2.303920] sd 0:0:0:0: [sda] 250069680 512-byte logical blocks: (128 GB/119 GiB) [ 2.304213] sd 0:0:0:0: [sda] Write Protect is off [ 2.304225] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 2.304471] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 2.306818] sda: sda1 sda2 < sda5 > [ 2.308780] sd 0:0:0:0: [sda] Attached SCSI disk [ 2.318162] Refined TSC clocksource calibration: 1595.999 MHz. [ 2.318169] usb 1-1: new high-speed USB device number 2 using ehci_hcd [ 2.318178] Switching to clocksource tsc [ 2.450939] hub 1-1:1.0: USB hub found [ 2.451121] hub 1-1:1.0: 6 ports detected [ 2.561786] usb 2-1: new high-speed USB device number 2 using ehci_hcd [ 2.621757] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300) [ 2.636143] ata2.00: ATAPI: TSSTcorp DVD+/-RW TS-T633C, D800, max UDMA/100 [ 2.636152] ata2.00: applying bridge limits [ 2.649711] ata2.00: configured for UDMA/100 [ 2.653762] scsi 1:0:0:0: CD-ROM TSSTcorp DVD+-RW TS-T633C D800 PQ: 0 ANSI: 5 [ 2.661486] sr0: scsi3-mmc drive: 24x/24x writer dvd-ram cd/rw xa/form2 cdda tray [ 2.661494] cdrom: Uniform CD-ROM driver Revision: 3.20 [ 2.661890] sr 1:0:0:0: Attached scsi CD-ROM sr0 [ 2.662156] sr 1:0:0:0: Attached scsi generic sg1 type 5 [ 2.694649] hub 2-1:1.0: USB hub found [ 2.694840] hub 2-1:1.0: 8 ports detected [ 2.765823] usb 1-1.4: new high-speed USB device number 3 using ehci_hcd [ 2.981454] ata6: SATA link down (SStatus 0 SControl 300) [ 2.982597] Freeing unused kernel memory: 740k freed [ 2.983523] Write protecting the kernel text: 5816k [ 2.983808] Write protecting the kernel read-only data: 2376k [ 2.983811] NX-protecting the kernel data: 4424k [ 3.014594] udevd[127]: starting version 175 [ 3.068925] sdhci: Secure Digital Host Controller Interface driver [ 3.068932] sdhci: Copyright(c) Pierre Ossman [ 3.069714] sdhci-pci 0000:09:00.0: SDHCI controller found [1180:e822] (rev 1) [ 3.069742] sdhci-pci 0000:09:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 [ 3.069786] sdhci-pci 0000:09:00.0: Will use DMA mode even though HW doesn't fully claim to support it. [ 3.069798] sdhci-pci 0000:09:00.0: setting latency timer to 64 [ 3.069816] mmc0: no vmmc regulator found [ 3.069877] Registered led device: mmc0:: [ 3.070946] mmc0: SDHCI controller on PCI [0000:09:00.0] using DMA [ 3.071078] tg3.c:v3.121 (November 2, 2011) [ 3.071252] tg3 0000:0b:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [ 3.071269] tg3 0000:0b:00.0: setting latency timer to 64 [ 3.071403] firewire_ohci 0000:09:00.3: PCI INT D -> GSI 19 (level, low) -> IRQ 19 [ 3.071417] firewire_ohci 0000:09:00.3: setting latency timer to 64 [ 3.078509] EXT4-fs (sda1): INFO: recovery required on readonly filesystem [ 3.078517] EXT4-fs (sda1): write access will be enabled during recovery [ 3.110417] tg3 0000:0b:00.0: eth0: Tigon3 [partno(BCM95784M) rev 5784100] (PCI Express) MAC address b8:ac:6f:71:02:a6 [ 3.110425] tg3 0000:0b:00.0: eth0: attached PHY is 5784 (10/100/1000Base-T Ethernet) (WireSpeed[1], EEE[0]) [ 3.110431] tg3 0000:0b:00.0: eth0: RXcsums[1] LinkChgREG[0] MIirq[0] ASF[0] TSOcap[1] [ 3.110436] tg3 0000:0b:00.0: eth0: dma_rwctrl[76180000] dma_mask[64-bit] [ 3.125492] firewire_ohci: Added fw-ohci device 0000:09:00.3, OHCI v1.10, 4 IR + 4 IT contexts, quirks 0x11 [ 3.390124] EXT4-fs (sda1): orphan cleanup on readonly fs [ 3.390135] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078710 [ 3.390232] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 2363071 [ 3.390327] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078711 [ 3.390350] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078709 [ 3.390367] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078708 [ 3.390384] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078707 [ 3.390401] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078706 [ 3.390417] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078705 [ 3.390435] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078551 [ 3.390452] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078523 [ 3.390470] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7078520 [ 3.390487] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 7077901 [ 3.390551] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 4063272 [ 3.390562] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 4063266 [ 3.390572] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 4063261 [ 3.390582] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 4063256 [ 3.390592] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 4063255 [ 3.390602] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 2363072 [ 3.390620] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 2360050 [ 3.390698] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 5250064 [ 3.390710] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 2365394 [ 3.390728] EXT4-fs (sda1): ext4_orphan_cleanup: deleting unreferenced inode 2365390 [ 3.390745] EXT4-fs (sda1): 22 orphan inodes deleted [ 3.390748] EXT4-fs (sda1): recovery complete [ 3.397636] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null) [ 3.624910] firewire_core: created device fw0: GUID 464fc000110e2661, S400 [ 3.927467] ADDRCONF(NETDEV_UP): eth0: link is not ready [ 3.929965] udevd[400]: starting version 175 [ 3.933581] Adding 6278140k swap on /dev/sda5. Priority:-1 extents:1 across:6278140k SS [ 3.945183] lp: driver loaded but no devices found [ 3.999389] wmi: Mapper loaded [ 4.016696] ite_cir: Auto-detected model: ITE8708 CIR transceiver [ 4.016702] ite_cir: Using model: ITE8708 CIR transceiver [ 4.016706] ite_cir: TX-capable: 1 [ 4.016710] ite_cir: Sample period (ns): 8680 [ 4.016713] ite_cir: TX carrier frequency (Hz): 38000 [ 4.016716] ite_cir: TX duty cycle (%): 33 [ 4.016719] ite_cir: RX low carrier frequency (Hz): 0 [ 4.016722] ite_cir: RX high carrier frequency (Hz): 0 [ 4.025684] fglrx: module license 'Proprietary. (C) 2002 - ATI Technologies, Starnberg, GERMANY' taints kernel. [ 4.025691] Disabling lock debugging due to kernel taint [ 4.027410] IR NEC protocol handler initialized [ 4.030250] lib80211: common routines for IEEE802.11 drivers [ 4.030257] lib80211_crypt: registered algorithm 'NULL' [ 4.036024] IR RC5(x) protocol handler initialized [ 4.036092] snd_hda_intel 0000:00:1b.0: PCI INT A -> GSI 22 (level, low) -> IRQ 22 [ 4.036188] snd_hda_intel 0000:00:1b.0: irq 46 for MSI/MSI-X [ 4.036307] snd_hda_intel 0000:00:1b.0: setting latency timer to 64 [ 4.036361] [Firmware Bug]: ACPI: No _BQC method, cannot determine initial brightness [ 4.039006] acpi device:03: registered as cooling_device10 [ 4.039164] input: Video Bus as /devices/LNXSYSTM:00/device:00/PNP0A08:00/device:01/LNXVIDEO:00/input/input5 [ 4.039261] ACPI: Video Device [M86] (multi-head: yes rom: no post: no) [ 4.049753] EXT4-fs (sda1): re-mounted. Opts: errors=remount-ro [ 4.050201] wl 0000:05:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [ 4.050215] wl 0000:05:00.0: setting latency timer to 64 [ 4.052252] Registered IR keymap rc-rc6-mce [ 4.052432] input: ITE8708 CIR transceiver as /devices/virtual/rc/rc0/input6 [ 4.054614] IR RC6 protocol handler initialized [ 4.054787] rc0: ITE8708 CIR transceiver as /devices/virtual/rc/rc0 [ 4.054839] ite_cir: driver has been successfully loaded [ 4.057338] IR JVC protocol handler initialized [ 4.061553] IR Sony protocol handler initialized [ 4.066578] input: MCE IR Keyboard/Mouse (ite-cir) as /devices/virtual/input/input7 [ 4.066724] IR MCE Keyboard/mouse protocol handler initialized [ 4.072580] lirc_dev: IR Remote Control driver registered, major 250 [ 4.073280] rc rc0: lirc_dev: driver ir-lirc-codec (ite-cir) registered at minor = 0 [ 4.073286] IR LIRC bridge handler initialized [ 4.077849] Linux video capture interface: v2.00 [ 4.079402] uvcvideo: Found UVC 1.00 device Laptop_Integrated_Webcam_2M (0c45:640f) [ 4.085492] EDAC MC: Ver: 2.1.0 [ 4.087138] lib80211_crypt: registered algorithm 'TKIP' [ 4.091027] input: HDA Intel Mic as /devices/pci0000:00/0000:00:1b.0/sound/card0/input8 [ 4.091733] snd_hda_intel 0000:02:00.1: PCI INT B -> GSI 17 (level, low) -> IRQ 17 [ 4.091826] snd_hda_intel 0000:02:00.1: irq 47 for MSI/MSI-X [ 4.091861] snd_hda_intel 0000:02:00.1: setting latency timer to 64 [ 4.093115] EDAC i7core: Device not found: dev 00.0 PCI ID 8086:2c50 [ 4.112448] HDMI status: Codec=0 Pin=3 Presence_Detect=0 ELD_Valid=0 [ 4.112612] input: HD-Audio Generic HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:03.0/0000:02:00.1/sound/card1/input9 [ 4.113311] type=1400 audit(1342032325.540:2): apparmor="STATUS" operation="profile_load" name="/sbin/dhclient" pid=658 comm="apparmor_parser" [ 4.114501] type=1400 audit(1342032325.540:3): apparmor="STATUS" operation="profile_load" name="/usr/lib/NetworkManager/nm-dhcp-client.action" pid=658 comm="apparmor_parser" [ 4.115253] type=1400 audit(1342032325.540:4): apparmor="STATUS" operation="profile_load" name="/usr/lib/connman/scripts/dhclient-script" pid=658 comm="apparmor_parser" [ 4.121870] input: Laptop_Integrated_Webcam_2M as /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.4/1-1.4:1.0/input/input10 [ 4.122096] usbcore: registered new interface driver uvcvideo [ 4.122100] USB Video Class driver (1.1.1) [ 4.128729] [fglrx] Maximum main memory to use for locked dma buffers: 5840 MBytes. [ 4.129678] [fglrx] vendor: 1002 device: 68c0 count: 1 [ 4.131991] [fglrx] ioport: bar 4, base 0x2000, size: 0x100 [ 4.132015] pci 0000:02:00.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 [ 4.132024] pci 0000:02:00.0: setting latency timer to 64 [ 4.133712] [fglrx] Kernel PAT support is enabled [ 4.133747] [fglrx] module loaded - fglrx 8.96.4 [Mar 12 2012] with 1 minors [ 4.162666] eth1: Broadcom BCM4727 802.11 Hybrid Wireless Controller 5.100.82.38 [ 4.184133] device-mapper: multipath: version 1.3.0 loaded [ 4.196660] dcdbas dcdbas: Dell Systems Management Base Driver (version 5.6.0-3.2) [ 4.279897] input: Dell WMI hotkeys as /devices/virtual/input/input11 [ 4.292402] Bluetooth: Core ver 2.16 [ 4.292449] NET: Registered protocol family 31 [ 4.292454] Bluetooth: HCI device and connection manager initialized [ 4.292459] Bluetooth: HCI socket layer initialized [ 4.292463] Bluetooth: L2CAP socket layer initialized [ 4.292473] Bluetooth: SCO socket layer initialized [ 4.296333] Bluetooth: RFCOMM TTY layer initialized [ 4.296342] Bluetooth: RFCOMM socket layer initialized [ 4.296345] Bluetooth: RFCOMM ver 1.11 [ 4.313586] ppdev: user-space parallel port driver [ 4.316619] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 [ 4.316625] Bluetooth: BNEP filters: protocol multicast [ 4.383980] type=1400 audit(1342032325.812:5): apparmor="STATUS" operation="profile_load" name="/usr/lib/cups/backend/cups-pdf" pid=938 comm="apparmor_parser" [ 4.385173] type=1400 audit(1342032325.812:6): apparmor="STATUS" operation="profile_load" name="/usr/sbin/cupsd" pid=938 comm="apparmor_parser" [ 4.425757] init: failsafe main process (898) killed by TERM signal [ 4.477052] type=1400 audit(1342032325.904:7): apparmor="STATUS" operation="profile_replace" name="/sbin/dhclient" pid=1011 comm="apparmor_parser" [ 4.477592] type=1400 audit(1342032325.904:8): apparmor="STATUS" operation="profile_load" name="/usr/lib/lightdm/lightdm/lightdm-guest-session-wrapper" pid=1010 comm="apparmor_parser" [ 4.478099] type=1400 audit(1342032325.904:9): apparmor="STATUS" operation="profile_load" name="/usr/sbin/tcpdump" pid=1017 comm="apparmor_parser" [ 4.479233] type=1400 audit(1342032325.904:10): apparmor="STATUS" operation="profile_load" name="/usr/lib/telepathy/mission-control-5" pid=1014 comm="apparmor_parser" [ 4.510060] vesafb: mode is 1152x864x32, linelength=4608, pages=0 [ 4.510065] vesafb: scrolling: redraw [ 4.510071] vesafb: Truecolor: size=0:8:8:8, shift=0:16:8:0 [ 4.510084] mtrr: no more MTRRs available [ 4.513081] vesafb: framebuffer at 0xd0000000, mapped to 0xf9400000, using 3904k, total 3904k [ 4.515203] Console: switching to colour frame buffer device 144x54 [ 4.515278] fb0: VESA VGA frame buffer device [ 4.590743] tg3 0000:0b:00.0: irq 48 for MSI/MSI-X [ 4.702009] ADDRCONF(NETDEV_UP): eth0: link is not ready [ 4.704409] ADDRCONF(NETDEV_UP): eth0: link is not ready [ 4.978379] psmouse serio1: synaptics: Touchpad model: 1, fw: 7.2, id: 0x1c0b1, caps: 0xd04733/0xa40000/0xa0000 [ 5.030104] input: SynPS/2 Synaptics TouchPad as /devices/platform/i8042/serio1/input/input12 [ 5.045782] kvm: VM_EXIT_LOAD_IA32_PERF_GLOBAL_CTRL does not work properly. Using workaround [ 5.519573] [fglrx] ATIF platform detected with notification ID: 0x81 [ 6.391466] fglrx_pci 0000:02:00.0: irq 49 for MSI/MSI-X [ 6.393137] [fglrx] Firegl kernel thread PID: 1305 [ 6.393306] [fglrx] Firegl kernel thread PID: 1306 [ 6.393472] [fglrx] Firegl kernel thread PID: 1307 [ 6.393726] [fglrx] IRQ 49 Enabled [ 6.528052] postgres (1308): /proc/1308/oom_adj is deprecated, please use /proc/1308/oom_score_adj instead. [ 6.532080] [fglrx] Gart USWC size:1280 M. [ 6.532084] [fglrx] Gart cacheable size:508 M. [ 6.532091] [fglrx] Reserved FB block: Shared offset:0, size:1000000 [ 6.532094] [fglrx] Reserved FB block: Unshared offset:f8fd000, size:403000 [ 6.532098] [fglrx] Reserved FB block: Unshared offset:3fff4000, size:c000 [ 17.423743] eth1: no IPv6 routers present [ 75.836426] warning: `proftpd' uses 32-bit capabilities (legacy support in use) [ 75.884215] init: plymouth-stop pre-start process (2922) terminated with status 1 [ 543.679614] eth1: no IPv6 routers present lsmod Module Size Used by kvm_intel 127560 0 kvm 359456 1 kvm_intel joydev 17393 0 vesafb 13516 1 parport_pc 32114 0 bnep 17830 2 ppdev 12849 0 rfcomm 38139 0 bluetooth 158438 10 bnep,rfcomm dell_wmi 12601 0 sparse_keymap 13658 1 dell_wmi binfmt_misc 17292 1 dell_laptop 17767 0 dcdbas 14098 1 dell_laptop dm_multipath 22710 0 fglrx 2909855 143 snd_hda_codec_hdmi 31775 1 psmouse 72919 0 serio_raw 13027 0 i7core_edac 23382 0 lib80211_crypt_tkip 17275 0 edac_core 46858 1 i7core_edac uvcvideo 67203 0 snd_hda_codec_idt 60251 1 videodev 86588 1 uvcvideo ir_lirc_codec 12739 0 lirc_dev 18700 1 ir_lirc_codec ir_mce_kbd_decoder 12681 0 snd_seq_midi 13132 0 ir_sony_decoder 12462 0 ir_jvc_decoder 12459 0 snd_rawmidi 25424 1 snd_seq_midi ir_rc6_decoder 12459 0 wl 2646601 0 snd_seq_midi_event 14475 1 snd_seq_midi snd_seq 51567 2 snd_seq_midi,snd_seq_midi_event ir_rc5_decoder 12459 0 video 19068 0 snd_hda_intel 32765 5 snd_seq_device 14172 3 snd_seq_midi,snd_rawmidi,snd_seq snd_hda_codec 109562 3 snd_hda_codec_hdmi,snd_hda_codec_idt,snd_hda_intel rc_rc6_mce 12454 0 lib80211 14040 2 lib80211_crypt_tkip,wl snd_hwdep 13276 1 snd_hda_codec ir_nec_decoder 12459 0 snd_pcm 80845 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec ite_cir 24743 0 rc_core 21263 10 ir_lirc_codec,ir_mce_kbd_decoder,ir_sony_decoder,ir_jvc_decoder,ir_rc6_decoder,ir_rc5_decoder,rc_rc6_mce,ir_nec_decoder,ite_cir snd_timer 28931 2 snd_seq,snd_pcm wmi 18744 1 dell_wmi snd 62064 20 snd_hda_codec_hdmi,snd_hda_codec_idt,snd_rawmidi,snd_seq,snd_seq_device,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_timer mac_hid 13077 0 soundcore 14635 1 snd snd_page_alloc 14108 2 snd_hda_intel,snd_pcm coretemp 13269 0 lp 17455 0 parport 40930 3 parport_pc,ppdev,lp tg3 141369 0 firewire_ohci 40172 0 sdhci_pci 18324 0 firewire_core 56906 1 firewire_ohci sdhci 28241 1 sdhci_pci crc_itu_t 12627 1 firewire_core lshw *-network description: Wireless interface product: BCM4313 802.11b/g/n Wireless LAN Controller vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:05:00.0 logical name: eth1 version: 01 serial: 70:f1:a1:a9:54:31 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=wl0 driverversion=5.100.82.38 ip=192.168.0.117 latency=0 multicast=yes wireless=IEEE 802.11 resources: irq:17 memory:f0900000-f0903fff *-network description: Ethernet interface product: NetLink BCM5784M Gigabit Ethernet PCIe vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:0b:00.0 logical name: eth0 version: 10 serial: b8:ac:6f:71:02:a6 capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm vpd msi pciexpress bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.121 firmware=sb v2.19 latency=0 link=no multicast=yes port=twisted pair resources: irq:48 memory:f0d00000-f0d0ffff

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• F# - Facebook Hacker Cup - Double Squares

  - by Jacob

  I'm working on strengthening my F#-fu and decided to tackle the Facebook Hacker Cup Double Squares problem. I'm having some problems with the run-time and was wondering if anyone could help me figure out why it is so much slower than my C# equivalent. There's a good description from another post; Source: Facebook Hacker Cup Qualification Round 2011 A double-square number is an integer X which can be expressed as the sum of two perfect squares. For example, 10 is a double-square because 10 = 3^2 + 1^2. Given X, how can we determine the number of ways in which it can be written as the sum of two squares? For example, 10 can only be written as 3^2 + 1^2 (we don't count 1^2 + 3^2 as being different). On the other hand, 25 can be written as 5^2 + 0^2 or as 4^2 + 3^2. You need to solve this problem for 0 = X = 2,147,483,647. Examples: 10 = 1 25 = 2 3 = 0 0 = 1 1 = 1 My basic strategy (which I'm open to critique on) is to; Create a dictionary (for memoize) of the input numbers initialzed to 0 Get the largest number (LN) and pass it to count/memo function Get the LN square root as int Calculate squares for all numbers 0 to LN and store in dict Sum squares for non repeat combinations of numbers from 0 to LN If sum is in memo dict, add 1 to memo Finally, output the counts of the original numbers. Here is the F# code (See code changes at bottom) I've written that I believe corresponds to this strategy (Runtime: ~8:10); open System open System.Collections.Generic open System.IO /// Get a sequence of values let rec range min max = seq { for num in [min .. max] do yield num } /// Get a sequence starting from 0 and going to max let rec zeroRange max = range 0 max /// Find the maximum number in a list with a starting accumulator (acc) let rec maxNum acc = function | [] -> acc | p::tail when p > acc -> maxNum p tail | p::tail -> maxNum acc tail /// A helper for finding max that sets the accumulator to 0 let rec findMax nums = maxNum 0 nums /// Build a collection of combinations; ie [1,2,3] = (1,1), (1,2), (1,3), (2,2), (2,3), (3,3) let rec combos range = seq { let count = ref 0 for inner in range do for outer in Seq.skip !count range do yield (inner, outer) count := !count + 1 } let rec squares nums = let dict = new Dictionary<int, int>() for s in nums do dict.[s] <- (s * s) dict /// Counts the number of possible double squares for a given number and keeps track of other counts that are provided in the memo dict. let rec countDoubleSquares (num: int) (memo: Dictionary<int, int>) = // The highest relevent square is the square root because it squared plus 0 squared is the top most possibility let maxSquare = System.Math.Sqrt((float)num) // Our relevant squares are 0 to the highest possible square; note the cast to int which shouldn't hurt. let relSquares = range 0 ((int)maxSquare) // calculate the squares up front; let calcSquares = squares relSquares // Build up our square combinations; ie [1,2,3] = (1,1), (1,2), (1,3), (2,2), (2,3), (3,3) for (sq1, sq2) in combos relSquares do let v = calcSquares.[sq1] + calcSquares.[sq2] // Memoize our relevant results if memo.ContainsKey(v) then memo.[v] <- memo.[v] + 1 // return our count for the num passed in memo.[num] // Read our numbers from file. //let lines = File.ReadAllLines("test2.txt") //let nums = [ for line in Seq.skip 1 lines -> Int32.Parse(line) ] // Optionally, read them from straight array let nums = [1740798996; 1257431873; 2147483643; 602519112; 858320077; 1048039120; 415485223; 874566596; 1022907856; 65; 421330820; 1041493518; 5; 1328649093; 1941554117; 4225; 2082925; 0; 1; 3] // Initialize our memoize dictionary let memo = new Dictionary<int, int>() for num in nums do memo.[num] <- 0 // Get the largest number in our set, all other numbers will be memoized along the way let maxN = findMax nums // Do the memoize let maxCount = countDoubleSquares maxN memo // Output our results. for num in nums do printfn "%i" memo.[num] // Have a little pause for when we debug let line = Console.Read() And here is my version in C# (Runtime: ~1:40: using System; using System.Collections.Generic; using System.Diagnostics; using System.IO; using System.Linq; using System.Text; namespace FBHack_DoubleSquares { public class TestInput { public int NumCases { get; set; } public List<int> Nums { get; set; } public TestInput() { Nums = new List<int>(); } public int MaxNum() { return Nums.Max(); } } class Program { static void Main(string[] args) { // Read input from file. //TestInput input = ReadTestInput("live.txt"); // As example, load straight. TestInput input = new TestInput { NumCases = 20, Nums = new List<int> { 1740798996, 1257431873, 2147483643, 602519112, 858320077, 1048039120, 415485223, 874566596, 1022907856, 65, 421330820, 1041493518, 5, 1328649093, 1941554117, 4225, 2082925, 0, 1, 3, } }; var maxNum = input.MaxNum(); Dictionary<int, int> memo = new Dictionary<int, int>(); foreach (var num in input.Nums) { if (!memo.ContainsKey(num)) memo.Add(num, 0); } DoMemoize(maxNum, memo); StringBuilder sb = new StringBuilder(); foreach (var num in input.Nums) { //Console.WriteLine(memo[num]); sb.AppendLine(memo[num].ToString()); } Console.Write(sb.ToString()); var blah = Console.Read(); //File.WriteAllText("out.txt", sb.ToString()); } private static int DoMemoize(int num, Dictionary<int, int> memo) { var highSquare = (int)Math.Floor(Math.Sqrt(num)); var squares = CreateSquareLookup(highSquare); var relSquares = squares.Keys.ToList(); Debug.WriteLine("Starting - " + num.ToString()); Debug.WriteLine("RelSquares.Count = {0}", relSquares.Count); int sum = 0; var index = 0; foreach (var square in relSquares) { foreach (var inner in relSquares.Skip(index)) { sum = squares[square] + squares[inner]; if (memo.ContainsKey(sum)) memo[sum]++; } index++; } if (memo.ContainsKey(num)) return memo[num]; return 0; } private static TestInput ReadTestInput(string fileName) { var lines = File.ReadAllLines(fileName); var input = new TestInput(); input.NumCases = int.Parse(lines[0]); foreach (var lin in lines.Skip(1)) { input.Nums.Add(int.Parse(lin)); } return input; } public static Dictionary<int, int> CreateSquareLookup(int maxNum) { var dict = new Dictionary<int, int>(); int square; foreach (var num in Enumerable.Range(0, maxNum)) { square = num * num; dict[num] = square; } return dict; } } } Thanks for taking a look. UPDATE Changing the combos function slightly will result in a pretty big performance boost (from 8 min to 3:45): /// Old and Busted... let rec combosOld range = seq { let rangeCache = Seq.cache range let count = ref 0 for inner in rangeCache do for outer in Seq.skip !count rangeCache do yield (inner, outer) count := !count + 1 } /// The New Hotness... let rec combos maxNum = seq { for i in 0..maxNum do for j in i..maxNum do yield i,j }

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• LSI MegaRAID Expected Chip Temperature?

  - by Myles Gray

  We recently built a replicating SAN array from 2x Dell R720XD's, we are using LSI 9270-8i MegaRAID cards with CacheCade 2.0, BBU and Write Back cache enabled. Our cards are showing HUGE chip temperatures (97*C+ with NO disk activity!). Our R720's are in auto temp management mode so the max exhaust temp is 50*C. The MegaRAID cards are passively cooled and depend on good airflow to cool them - however is 97*C normal? - I have seen reference to 60*C max ambients but nothing for chip temp.

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• Apache2 benchmarks - very poor performance

  - by andrzejp

  I have two servers on which I test the configuration of apache2. The first server: 4GB of RAM, AMD Athlon (tm) 64 X2 Dual Core Processor 5600 + Apache 2.2.3, mod_php, mpm prefork: Settings: Timeout 100 KeepAlive On MaxKeepAliveRequests 150 KeepAliveTimeout 4 <IfModule Mpm_prefork_module> StartServers 7 MinSpareServers 15 MaxSpareServers 30 MaxClients 250 MaxRequestsPerChild 2000 </ IfModule> Compiled in modules: core.c mod_log_config.c mod_logio.c prefork.c http_core.c mod_so.c Second server: 8GB of RAM, Intel (R) Core (TM) i7 CPU [email protected] Apache 2.2.9, **fcgid, mpm worker, suexec** PHP scripts are running via fcgi-wrapper Settings: Timeout 100 KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 4 <IfModule Mpm_worker_module> StartServers 10 MaxClients 200 MinSpareThreads 25 MaxSpareThreads 75 ThreadsPerChild 25 MaxRequestsPerChild 1000 </ IfModule> Compiled in modules: core.c mod_log_config.c mod_logio.c worker.c http_core.c mod_so.c The following test results, which are very strange! New server (dynamic content - php via fcgid+suexec): Server Software: Apache/2.2.9 Server Hostname: XXXXXXXX Server Port: 80 Document Path: XXXXXXX Document Length: 179512 bytes Concurrency Level: 10 Time taken for tests: 0.26276 seconds Complete requests: 1000 Failed requests: 0 Total transferred: 179935000 bytes HTML transferred: 179512000 bytes Requests per second: 38.06 Transfer rate: 6847.88 kb/s received Connnection Times (ms) min avg max Connect: 2 4 54 Processing: 161 257 449 Total: 163 261 503 Old server (dynamic content - mod_php): Server Software: Apache/2.2.3 Server Hostname: XXXXXX Server Port: 80 Document Path: XXXXXX Document Length: 187537 bytes Concurrency Level: 10 Time taken for tests: 173.073 seconds Complete requests: 1000 Failed requests: 22 (Connect: 0, Length: 22, Exceptions: 0) Total transferred: 188003372 bytes HTML transferred: 187546372 bytes Requests per second: 5777.91 Transfer rate: 1086267.40 kb/s received Connnection Times (ms) min avg max Connect: 3 3 28 Processing: 298 1724 26615 Total: 301 1727 26643 Old server: Static content (jpg file) Server Software: Apache/2.2.3 Server Hostname: xxxxxxxxx Server Port: 80 Document Path: /images/top2.gif Document Length: 40486 bytes Concurrency Level: 100 Time taken for tests: 3.558 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 40864400 bytes HTML transferred: 40557482 bytes Requests per second: 281.09 [#/sec] (mean) Time per request: 355.753 [ms] (mean) Time per request: 3.558 [ms] (mean, across all concurrent requests) Transfer rate: 11217.51 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 3 11 4.5 12 23 Processing: 40 329 61.4 339 1009 Waiting: 6 282 55.2 293 737 Total: 43 340 63.0 351 1020 New server - static content (jpg file) Server Software: Apache/2.2.9 Server Hostname: XXXXX Server Port: 80 Document Path: /images/top2.gif Document Length: 40486 bytes Concurrency Level: 100 Time taken for tests: 3.571531 seconds Complete requests: 1000 Failed requests: 0 Write errors: 0 Total transferred: 41282792 bytes HTML transferred: 41030080 bytes Requests per second: 279.99 [#/sec] (mean) Time per request: 357.153 [ms] (mean) Time per request: 3.572 [ms] (mean, across all concurrent requests) Transfer rate: 11287.88 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 2 63 24.8 66 119 Processing: 124 278 31.8 282 391 Waiting: 3 70 28.5 66 164 Total: 126 341 35.9 350 443 I noticed that in the apache error.log is a lot of entries: [notice] mod_fcgid: call /www/XXXXX/public_html/forum/index.php with wrapper /www/php-fcgi-scripts/XXXXXX/php-fcgi-starter What I have omitted, or do not understand? Such a difference in requests per second? Is it possible? What could be the cause?

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• MySQL: Pacemaker cannot start the failed master as a new slave?

  - by quanta

  I'm going to setup failover for MySQL replication (1 master and 1 slave) follow this guide: https://github.com/jayjanssen/Percona-Pacemaker-Resource-Agents/blob/master/doc/PRM-setup-guide.rst Here're the output of crm configure show: node serving-6192 \ attributes p_mysql_mysql_master_IP="192.168.6.192" node svr184R-638.localdomain \ attributes p_mysql_mysql_master_IP="192.168.6.38" primitive p_mysql ocf:percona:mysql \ params config="/etc/my.cnf" pid="/var/run/mysqld/mysqld.pid" socket="/var/lib/mysql/mysql.sock" replication_user="repl" replication_passwd="x" test_user="test_user" test_passwd="x" \ op monitor interval="5s" role="Master" OCF_CHECK_LEVEL="1" \ op monitor interval="2s" role="Slave" timeout="30s" OCF_CHECK_LEVEL="1" \ op start interval="0" timeout="120s" \ op stop interval="0" timeout="120s" primitive writer_vip ocf:heartbeat:IPaddr2 \ params ip="192.168.6.8" cidr_netmask="32" \ op monitor interval="10s" \ meta is-managed="true" ms ms_MySQL p_mysql \ meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1" notify="true" globally-unique="false" target-role="Master" is-managed="true" colocation writer_vip_on_master inf: writer_vip ms_MySQL:Master order ms_MySQL_promote_before_vip inf: ms_MySQL:promote writer_vip:start property $id="cib-bootstrap-options" \ dc-version="1.0.12-unknown" \ cluster-infrastructure="openais" \ expected-quorum-votes="2" \ no-quorum-policy="ignore" \ stonith-enabled="false" \ last-lrm-refresh="1341801689" property $id="mysql_replication" \ p_mysql_REPL_INFO="192.168.6.192|mysql-bin.000006|338" crm_mon: Last updated: Mon Jul 9 10:30:01 2012 Stack: openais Current DC: serving-6192 - partition with quorum Version: 1.0.12-unknown 2 Nodes configured, 2 expected votes 2 Resources configured. ============ Online: [ serving-6192 svr184R-638.localdomain ] Master/Slave Set: ms_MySQL Masters: [ serving-6192 ] Slaves: [ svr184R-638.localdomain ] writer_vip (ocf::heartbeat:IPaddr2): Started serving-6192 Editing /etc/my.cnf on the serving-6192 of wrong syntax to test failover and it's working fine: svr184R-638.localdomain being promoted to become the master writer_vip switch to svr184R-638.localdomain Current state: Last updated: Mon Jul 9 10:35:57 2012 Stack: openais Current DC: serving-6192 - partition with quorum Version: 1.0.12-unknown 2 Nodes configured, 2 expected votes 2 Resources configured. ============ Online: [ serving-6192 svr184R-638.localdomain ] Master/Slave Set: ms_MySQL Masters: [ svr184R-638.localdomain ] Stopped: [ p_mysql:0 ] writer_vip (ocf::heartbeat:IPaddr2): Started svr184R-638.localdomain Failed actions: p_mysql:0_monitor_5000 (node=serving-6192, call=15, rc=7, status=complete): not running p_mysql:0_demote_0 (node=serving-6192, call=22, rc=7, status=complete): not running p_mysql:0_start_0 (node=serving-6192, call=26, rc=-2, status=Timed Out): unknown exec error Remove the wrong syntax from /etc/my.cnf on serving-6192, and restart corosync, what I would like to see is serving-6192 was started as a new slave but it doesn't: Failed actions: p_mysql:0_start_0 (node=serving-6192, call=4, rc=1, status=complete): unknown error Here're snippet of the logs which I'm suspecting: Jul 09 10:46:32 serving-6192 lrmd: [7321]: info: rsc:p_mysql:0:4: start Jul 09 10:46:32 serving-6192 lrmd: [7321]: info: RA output: (p_mysql:0:start:stderr) Error performing operation: The object/attribute does not exist Jul 09 10:46:32 serving-6192 crm_attribute: [7420]: info: Invoked: /usr/sbin/crm_attribute -N serving-6192 -l reboot --name readable -v 0 The full logs: http://fpaste.org/AyOZ/ The strange thing is I can starting it manually: export OCF_ROOT=/usr/lib/ocf export OCF_RESKEY_config="/etc/my.cnf" export OCF_RESKEY_pid="/var/run/mysqld/mysqld.pid" export OCF_RESKEY_socket="/var/lib/mysql/mysql.sock" export OCF_RESKEY_replication_user="repl" export OCF_RESKEY_replication_passwd="x" export OCF_RESKEY_test_user="test_user" export OCF_RESKEY_test_passwd="x" sh -x /usr/lib/ocf/resource.d/percona/mysql start: http://fpaste.org/RVGh/ Did I make something wrong?

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• Linux buffer cache effect on IO writes?

  - by Patrick LeBoutillier

  I'm copying large files (3 x 30G) between 2 filesystems on a Linux server (kernel 2.6.37, 16 cores, 32G RAM) and I'm getting poor performance. I suspect that the usage of the buffer cache is killing the I/O performance. To try and narrow down the problem I used fio directly on the SAS disk to monitor the performance. Here is the output of 2 fio runs (the first with direct=1, the second one direct=0): Config: [test] rw=write blocksize=32k size=20G filename=/dev/sda # direct=1 Run 1: test: (g=0): rw=write, bs=32K-32K/32K-32K, ioengine=sync, iodepth=1 Starting 1 process Jobs: 1 (f=1): [W] [100.0% done] [0K/205M /s] [0/6K iops] [eta 00m:00s] test: (groupid=0, jobs=1): err= 0: pid=4667 write: io=20,480MB, bw=199MB/s, iops=6,381, runt=102698msec clat (usec): min=104, max=13,388, avg=152.06, stdev=72.43 bw (KB/s) : min=192448, max=213824, per=100.01%, avg=204232.82, stdev=4084.67 cpu : usr=3.37%, sys=16.55%, ctx=655410, majf=0, minf=29 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued r/w: total=0/655360, short=0/0 lat (usec): 250=99.50%, 500=0.45%, 750=0.01%, 1000=0.01% lat (msec): 2=0.01%, 4=0.02%, 10=0.01%, 20=0.01% Run status group 0 (all jobs): WRITE: io=20,480MB, aggrb=199MB/s, minb=204MB/s, maxb=204MB/s, mint=102698msec, maxt=102698msec Disk stats (read/write): sda: ios=0/655238, merge=0/0, ticks=0/79552, in_queue=78640, util=76.55% Run 2: test: (g=0): rw=write, bs=32K-32K/32K-32K, ioengine=sync, iodepth=1 Starting 1 process Jobs: 1 (f=1): [W] [100.0% done] [0K/0K /s] [0/0 iops] [eta 00m:00s] test: (groupid=0, jobs=1): err= 0: pid=4733 write: io=20,480MB, bw=91,265KB/s, iops=2,852, runt=229786msec clat (usec): min=16, max=127K, avg=349.53, stdev=4694.98 bw (KB/s) : min=56013, max=1390016, per=101.47%, avg=92607.31, stdev=167453.17 cpu : usr=0.41%, sys=6.93%, ctx=21128, majf=0, minf=33 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued r/w: total=0/655360, short=0/0 lat (usec): 20=5.53%, 50=93.89%, 100=0.02%, 250=0.01%, 500=0.01% lat (msec): 2=0.01%, 4=0.01%, 10=0.01%, 20=0.01%, 50=0.12% lat (msec): 100=0.38%, 250=0.04% Run status group 0 (all jobs): WRITE: io=20,480MB, aggrb=91,265KB/s, minb=93,455KB/s, maxb=93,455KB/s, mint=229786msec, maxt=229786msec Disk stats (read/write): sda: ios=8/79811, merge=7/7721388, ticks=9/32418456, in_queue=32471983, util=98.98% I'm not knowledgeable enough with fio to interpret the results, but I don't expect the overall performance using the buffer cache to be 50% less than with O_DIRECT. Can someone help me interpret the fio output? Are there any kernel tunings that could fix/minimize the problem? Thanks a lot,

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• Configuring varnish and django (apache/modwsgi)

  - by Hedde

  I am trying to work out why my application keeps hitting the database while I have setup varnish infront of apache. I think I am missing some vital configuration, any tips are welcome This is my curl result: HTTP/1.1 200 OK Server: Apache/2.2.16 (Debian) Content-Language: en-us Vary: Accept,Accept-Encoding,Accept-Language,Cookie Cache-Control: s-maxage=60, no-transform, max-age=60 Content-Type: application/json; charset=utf-8 Date: Sat, 15 Sep 2012 08:19:17 GMT Connection: keep-alive My varnishlog: 13 BackendClose - apache 13 BackendOpen b apache 127.0.0.1 47665 127.0.0.1 8000 13 TxRequest b GET 13 TxURL b /api/v1/events/?format=json 13 TxProtocol b HTTP/1.1 13 TxHeader b User-Agent: curl/7.19.7 (universal-apple-darwin10.0) libcurl/7.19.7 OpenSSL/0.9.8r zlib/1.2.3 13 TxHeader b Host: foobar.com 13 TxHeader b Accept: */* 13 TxHeader b X-Forwarded-For: 92.64.200.145 13 TxHeader b X-Varnish: 979305817 13 TxHeader b Accept-Encoding: gzip 13 RxProtocol b HTTP/1.1 13 RxStatus b 200 13 RxResponse b OK 13 RxHeader b Date: Sat, 15 Sep 2012 08:21:28 GMT 13 RxHeader b Server: Apache/2.2.16 (Debian) 13 RxHeader b Content-Language: en-us 13 RxHeader b Content-Encoding: gzip 13 RxHeader b Vary: Accept,Accept-Encoding,Accept-Language,Cookie 13 RxHeader b Cache-Control: s-maxage=60, no-transform, max-age=60 13 RxHeader b Content-Length: 6399 13 RxHeader b Content-Type: application/json; charset=utf-8 13 Fetch_Body b 4(length) cls 0 mklen 1 13 Length b 6399 13 BackendReuse b apache 11 SessionOpen c 92.64.200.145 53236 :80 11 ReqStart c 92.64.200.145 53236 979305817 11 RxRequest c HEAD 11 RxURL c /api/v1/events/?format=json 11 RxProtocol c HTTP/1.1 11 RxHeader c User-Agent: curl/7.19.7 (universal-apple-darwin10.0) libcurl/7.19.7 OpenSSL/0.9.8r zlib/1.2.3 11 RxHeader c Host: foobar.com 11 RxHeader c Accept: */* 11 VCL_call c recv lookup 11 VCL_call c hash 11 Hash c /api/v1/events/?format=json 11 Hash c foobar.com 11 VCL_return c hash 11 VCL_call c miss fetch 11 Backend c 13 apache apache 11 TTL c 979305817 RFC 60 -1 -1 1347697289 0 1347697288 0 60 11 VCL_call c fetch deliver 11 ObjProtocol c HTTP/1.1 11 ObjResponse c OK 11 ObjHeader c Date: Sat, 15 Sep 2012 08:21:28 GMT 11 ObjHeader c Server: Apache/2.2.16 (Debian) 11 ObjHeader c Content-Language: en-us 11 ObjHeader c Content-Encoding: gzip 11 ObjHeader c Vary: Accept,Accept-Encoding,Accept-Language,Cookie 11 ObjHeader c Cache-Control: s-maxage=60, no-transform, max-age=60 11 ObjHeader c Content-Type: application/json; charset=utf-8 11 Gzip c u F - 6399 69865 80 80 51128 11 VCL_call c deliver deliver 11 TxProtocol c HTTP/1.1 11 TxStatus c 200 11 TxResponse c OK 11 TxHeader c Server: Apache/2.2.16 (Debian) 11 TxHeader c Content-Language: en-us 11 TxHeader c Vary: Accept,Accept-Encoding,Accept-Language,Cookie 11 TxHeader c Cache-Control: s-maxage=60, no-transform, max-age=60 11 TxHeader c Content-Type: application/json; charset=utf-8 11 TxHeader c Date: Sat, 15 Sep 2012 08:21:29 GMT 11 TxHeader c Connection: keep-alive 11 Length c 0 11 ReqEnd c 979305817 1347697288.292612076 1347697289.456128597 0.000086784 1.163468122 0.000048399

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• Spanning-tree setup with incompatible switches

  - by wfaulk

  I have a set of eight HP ProCurve 2910al-48G Ethernet switches at my datacenter that are set up in a star topology with no physical loops. I want to partially mesh the switches for redundancy and manage the loops with a spanning-tree protocol. However, our connection to the datacenter is provided by two uplinks, each to a Cisco 3750. The datacenter's switches are handling the redundant connection using PVST spanning-tree, which is a Cisco-proprietary spanning-tree implementation that my HP switches do not support. It appears that my switches are not participating in the datacenter's spanning-tree domain, but are blindly passing the BPDUs between the two switchports on my side, which enables the datacenter's switches to recognize the loop and put one of the uplinks into the Blocking state. This is somewhat supposition, but I can confirm that, while my switches say that both of the uplink ports are forwarding, only one is passing any real quantity of data. (I am assuming that I cannot get the datacenter to move away from PVST. I don't know that I'd want them to make that significant of a change anyway.) The datacenter has also sent me this output from their switches (which I have expurgated of any identifiable info): 3750G-1#sh spanning-tree vlan nnn VLAN0nnn Spanning tree enabled protocol ieee Root ID Priority 10 Address 00d0.0114.xxxx Cost 4 Port 5 (GigabitEthernet1/0/5) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32mmm (priority 32768 sys-id-ext nnn) Address 0018.73d3.yyyy Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 sec Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Gi1/0/5 Root FWD 4 128.5 P2p Gi1/0/6 Altn BLK 4 128.6 P2p Gi1/0/8 Altn BLK 4 128.8 P2p and: 3750G-2#sh spanning-tree vlan nnn VLAN0nnn Spanning tree enabled protocol ieee Root ID Priority 10 Address 00d0.0114.xxxx Cost 4 Port 6 (GigabitEthernet1/0/6) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Bridge ID Priority 32mmm (priority 32768 sys-id-ext nnn) Address 000f.f71e.zzzz Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec Aging Time 300 sec Interface Role Sts Cost Prio.Nbr Type ------------------- ---- --- --------- -------- -------------------------------- Gi1/0/1 Desg FWD 4 128.1 P2p Gi1/0/5 Altn BLK 4 128.5 P2p Gi1/0/6 Root FWD 4 128.6 P2p Gi1/0/8 Desg FWD 4 128.8 P2p The uplinks to my switches are on Gi1/0/8 on both of their switches. The uplink ports are configured with a single tagged VLAN. I am also using a number of other tagged VLANs in my switch infrastructure. And, to be clear, I am passing the tagged VLAN I'm receiving from the datacenter to other ports on other switches in my infrastructure. My question is: how do I configure my switches so that I can use a spanning tree protocol inside my switch infrastructure without breaking the datacenter's spanning tree that I cannot participate in?

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• Varnish default.vcl grace period

  - by Vladimir

  These are my settings for a grace period (/etc/varnish/default.vcl) sub vcl_recv { .... set req.grace = 360000s; ... } sub vcl_fetch { ... set beresp.grace = 360000s; ... } I tested Varnish using localhost and nodejs as a server. I started localhost, the site was up. Then I disconnected server and the site got disconnected in less than 2 min. It says: Error 503 Service Unavailable Service Unavailable Guru Meditation: XID: 1890127100 Varnish cache server Could you tell me what could be the problem? sub vcl_fetch { if (beresp.ttl < 120s) { ##std.log("Adjusting TTL"); set beresp.ttl = 36000s; ##120s; } # Do not cache the object if the backend application does not want us to. if (beresp.http.Cache-Control ~ "(no-cache|no-store|private|must-revalidate)") { return(hit_for_pass); } # Do not cache the object if the status is not in the 200s if (beresp.status >= 300) { # Remove the Set-Cookie header #remove beresp.http.Set-Cookie; return(hit_for_pass); } # # Everything below here should be cached # # Remove the Set-Cookie header ####remove beresp.http.Set-Cookie; # Set the grace time ## set beresp.grace = 1s; //change this to minutes in case of app shutdown set beresp.grace = 360000s; ## 10 hour - reduce if it has negative impact # Static assets - browser caches tpiphem for a long time. if (req.url ~ "\.(css|js|.js|jpg|jpeg|gif|ico|png)\??\d*$") { /* Remove Expires from backend, it's not long enough */ unset beresp.http.expires; /* Set the clients TTL on this object */ set beresp.http.cache-control = "public, max-age=31536000"; /* marker for vcl_deliver to reset Age: */ set beresp.http.magicmarker = "1"; } else { set beresp.http.Cache-Control = "private, max-age=0, must-revalidate"; set beresp.http.Pragma = "no-cache"; } if (req.url ~ "\.(css|js|min|)\??\d*$") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } ##do not duplicate these settings if (req.url ~ ".css") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } if (req.url ~ ".js") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } if (req.url ~ ".min") { set beresp.do_gzip = true; unset beresp.http.expires; set beresp.http.cache-control = "public, max-age=31536000"; set beresp.http.expires = beresp.ttl; set beresp.http.age = "0"; } ## If the request to the backend returns a code other than 200, restart the loop ## If the number of restarts reaches the value of the parameter max_restarts, ## the request will be error'ed. max_restarts defaults to 4. This prevents ## an eternal loop in the event that, e.g., the object does not exist at all. if (beresp.status != 200 && beresp.status != 403 && beresp.status != 404) { return(restart); } if (beresp.status == 302) { return(deliver); } # Never cache posts if (req.url ~ "\/post\/" || req.url ~ "\/submit\/" || req.url ~ "\/ask\/" || req.url ~ "\/add\/") { return(hit_for_pass); } ##check this setting to ensure that it does not cause issues for browsers with no gzip if (beresp.http.content-type ~ "text") { set beresp.do_gzip = true; } if (beresp.http.Set-Cookie) { return(deliver); } ##if (req.url == "/index.html") { set beresp.do_esi = true; ##} ## check if this is needed or should be used # return(deliver); the object return(deliver); } sub vcl_recv { ##avoid leeching of images call hot_link; set req.grace = 360000s; ##2m ## if one backend is down - use another if (req.restarts == 0) { set req.backend = cache_director; ##we can specify individual VMs } else if (req.restarts == 1) { set req.backend = cache_director; } ## post calls should not be cached - add cookie for these requests if using micro-caching # Pass requests that are not GET or HEAD if (req.request != "GET" && req.request != "HEAD") { return(pass); ## return(pass) goes to backend - not cache } # Don't cache the result of a redirect if (req.http.Referer ~ "redir" || req.http.Origin ~ "jumpto") { return(pass); } # Don't cache the result of a redirect (asking for logon) if (req.http.Referer ~ "post" || req.http.Referer ~ "submit" || req.http.Referer ~ "add" || req.http.Referer ~ "ask") { return(pass); } # Never cache posts - ensure that we do not use these strings in our URLs' that need to be cached if (req.url ~ "\/post\/" || req.url ~ "\/submit\/" || req.url ~ "\/ask\/" || req.url ~ "\/add\/") { return(pass); } ## if (req.http.Authorization || req.http.Cookie) { if (req.http.Authorization) { /* Not cacheable by default */ return (pass); } # Handle compression correctly. Different browsers send different # "Accept-Encoding" headers, even though they mostly all support the same # compression mechanisms. By consolidating these compression headers into # a consistent format, we can reduce the size of the cache and get more hits. # @see: http:// varnish.projects.linpro.no/wiki/FAQ/Compression if (req.http.Accept-Encoding) { if (req.url ~ "\.(jpg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|ico)$") { # No point in compressing these remove req.http.Accept-Encoding; } else if (req.http.Accept-Encoding ~ "gzip") { # If the browser supports it, we'll use gzip. set req.http.Accept-Encoding = "gzip"; } else if (req.http.Accept-Encoding ~ "deflate") { # Next, try deflate if it is supported. set req.http.Accept-Encoding = "deflate"; } else { # Unknown algorithm. Remove it and send unencoded. unset req.http.Accept-Encoding; } } # lookup graphics, css, js & ico files in the cache if (req.url ~ "\.(png|gif|jpg|jpeg|css|.js|ico)$") { return(lookup); } ##added on 0918 - check if it causes issues with user specific content if (req.request == "GET" && req.http.cookie) { return(lookup); } # Pipe requests that are non-RFC2616 or CONNECT which is weird. if (req.request != "GET" && req.request != "HEAD" && req.request != "PUT" && req.request != "POST" && req.request != "TRACE" && req.request != "OPTIONS" && req.request != "DELETE") { ##closing connection and calling pipe return(pipe); } ##purge content via localhost only if (req.request == "PURGE") { if (!client.ip ~ purge) { error 405 "Not allowed."; } return(lookup); } ## do we need this? ## return(lookup); }

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• Linux buffer cache effect on IO writes?

  - by Patrick LeBoutillier

  Hi, I'm copying large files (3 x 30G) between 2 filesystems on a Linux server (kernel 2.6.37, 16 cores, 32G RAM) and I'm getting poor performance. I suspect that the usage of the buffer cache is killing the I/O performance. To try and narrow down the problem I used fio directly on the SAS disk to monitor the performance. Here is the output of 2 fio runs (the first with direct=1, the second one direct=0): Config: [test] rw=write blocksize=32k size=20G filename=/dev/sda # direct=1 Run 1: test: (g=0): rw=write, bs=32K-32K/32K-32K, ioengine=sync, iodepth=1 Starting 1 process Jobs: 1 (f=1): [W] [100.0% done] [0K/205M /s] [0/6K iops] [eta 00m:00s] test: (groupid=0, jobs=1): err= 0: pid=4667 write: io=20,480MB, bw=199MB/s, iops=6,381, runt=102698msec clat (usec): min=104, max=13,388, avg=152.06, stdev=72.43 bw (KB/s) : min=192448, max=213824, per=100.01%, avg=204232.82, stdev=4084.67 cpu : usr=3.37%, sys=16.55%, ctx=655410, majf=0, minf=29 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued r/w: total=0/655360, short=0/0 lat (usec): 250=99.50%, 500=0.45%, 750=0.01%, 1000=0.01% lat (msec): 2=0.01%, 4=0.02%, 10=0.01%, 20=0.01% Run status group 0 (all jobs): WRITE: io=20,480MB, aggrb=199MB/s, minb=204MB/s, maxb=204MB/s, mint=102698msec, maxt=102698msec Disk stats (read/write): sda: ios=0/655238, merge=0/0, ticks=0/79552, in_queue=78640, util=76.55% Run 2: test: (g=0): rw=write, bs=32K-32K/32K-32K, ioengine=sync, iodepth=1 Starting 1 process Jobs: 1 (f=1): [W] [100.0% done] [0K/0K /s] [0/0 iops] [eta 00m:00s] test: (groupid=0, jobs=1): err= 0: pid=4733 write: io=20,480MB, bw=91,265KB/s, iops=2,852, runt=229786msec clat (usec): min=16, max=127K, avg=349.53, stdev=4694.98 bw (KB/s) : min=56013, max=1390016, per=101.47%, avg=92607.31, stdev=167453.17 cpu : usr=0.41%, sys=6.93%, ctx=21128, majf=0, minf=33 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued r/w: total=0/655360, short=0/0 lat (usec): 20=5.53%, 50=93.89%, 100=0.02%, 250=0.01%, 500=0.01% lat (msec): 2=0.01%, 4=0.01%, 10=0.01%, 20=0.01%, 50=0.12% lat (msec): 100=0.38%, 250=0.04% Run status group 0 (all jobs): WRITE: io=20,480MB, aggrb=91,265KB/s, minb=93,455KB/s, maxb=93,455KB/s, mint=229786msec, maxt=229786msec Disk stats (read/write): sda: ios=8/79811, merge=7/7721388, ticks=9/32418456, in_queue=32471983, util=98.98% I'm not knowledgeable enough with fio to interpret the results, but I don't expect the overall performance using the buffer cache to be 50% less than with O_DIRECT. Can someone help me interpret the fio output? Are there any kernel tunings that could fix/minimize the problem? Thanks a lot,

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• What is the Dell E772c CRT Screen kWh consumption

  - by r0ca

  I have a Dell CRT Screen and the only info I have is this: AC input voltage / frequency / current : 90 to 264 VAC / 50 or 60 Hz + 3 Hz / 1.5 A max. (RMS) at 120 VAC and 0.8 A max.(RMS) at 220 VAC How can I calcultate the energy consumption in Watt for an hour or better, a day. Regards, David.

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• Given power info on a CRT monitor, how can I calculate power consumption (kWh)?

  - by r0ca

  I have a Dell CRT Screen and the only info I have is this: AC input voltage: 90 to 264 VAC frequency: 50 or 60 Hz + 3Hz current: 1.5A max. (RMS) at 120 VAC; or 0.8A max. (RMS) at 220 VAC How can I calculate the energy consumption in Watt-hours for an hour (or better, a day)?

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• Configure Apache with a htaccess file to strip out unneeded respond-headers.

  - by Koning Baard XIV

  For ultimate speed, I want my Apache server strip unneeded headers from the response. Currently, the headers looks like this (excluding the status header): Connection:Keep-Alive Content-Length:200 Content-Type:text/html Date:Sat, 15 May 2010 16:28:37 GMT Keep-Alive:timeout=5, max=100 Server:Apache/2.2.14 (Unix) mod_ssl/2.2.14 OpenSSL/0.9.8l DAV/2 PHP/5.3.1 Phusion_Passenger/2.2.7 X-Powered-By:PHP/5.3.1 Which I want to be like: Connection:Keep-Alive Content-Type:text/html Keep-Alive:timeout=5, max=100 How can I configure this in a .htaccess file? Thanks

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• Increase number of connections in IE7

  - by Dani

  I found some articles that explain how to increase number of connections in IE, "max connections per server", and "max connections per 1_0 server", I wondering if it will be works with a proxy server. thanks, Dani

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• Can I replace battery of My HP Pavilion DV6 2020e notebook to work for 3-5 hours ?

  - by Space Cracker

  I bought HP Pavilion DV6 2020e notebook from 6 months and i found that its battery last for max 70 minutes and i contact hp support and they told me that this model can last for max 90 minute according to its 6 cell battery :( Can any know if this model battery can be replaced by one that can last for 3-4 hours ?

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• Increase number of connections to IE7

  - by Dani

  I found some articles that explain how to increase number of connections in IE, "max connections per server", and "max connections per 1_0 server", I wondering if it will be works with a proxy

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• Is integrated graphics card Radeon HD 4200 capable to handle full HD?

  - by develroot

  I enjoy my integrated graphics card Radeon HD 4200 at resolution of 1280x1024 pixels on a 19" inches LG Flatron (5:4 aspect ratio) (playing FIFA 10 at max resolution, max quality). But recently i decided to upgrade my monitor and to get an 24" inches BENQ, 1920x1080, fullHD. Would I experience any problems with that graphics card on a such a big monitor? Usually I don't play games, just movies/music/and of programming, but it would be nice to be able to play some Counter Strike without artifacts.

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