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• SQL SERVER – Weekly Series – Memory Lane – #033

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Spatial Database Definition and Research Documents Here is the definition from Wikipedia about spatial database : A spatial database is a database that is optimized to store and query data related to objects in space, including points, lines and polygons. While typical databases can understand various numeric and character types of data, additional functionality needs to be added for databases to process spatial data types. Select Only Date Part From DateTime – Best Practice A very common question which I receive is how to only get Date or Time part from datetime value. In this blog post I explain the same in very simple words. T-SQL Paging Query Technique Comparison (OVER and ROW_NUMBER()) – CTE vs. Derived Table I have received few emails and comments about my post SQL SERVER – T-SQL Paging Query Technique Comparison – SQL 2000 vs SQL 2005. The main question was is this can be done using CTE? Absolutely! What about Performance? It is identical! Please refer above mentioned article for the history of paging. SQL SERVER – Cannot resolve collation conflict for equal to operation One of the very first error I ever encountered in my career was to resolve this conflict. I have blogged about it and I have realized that many others like me who are facing this error. LEN and DATALENGTH of NULL Simple Example Here is the question for you what is the LEN of NULL value? Well it is very easy – just read the blog. Recovery Models and Selection Very simple and easy explanation of the Database Backup Recovery Model and how to select the best option for you. Explanation SQL SERVER Hash Join Hash join gives best performance when two more join tables are joined and at-least one of them have no index or is not sorted. It is also expected that smaller of the either of table can be read in memory completely (though not necessary). Easy Sequence of SELECT FROM JOIN WHERE GROUP BY HAVING ORDER BY SELECT yourcolumns FROM tablenames JOIN tablenames WHERE condition GROUP BY yourcolumns HAVING aggregatecolumn condition ORDER BY yourcolumns NorthWind Database or AdventureWorks Database – Samples Databases In this blog post we learn how to install Northwind database. I also shared the source where one can download this database as that is used in many examples on MSDN help files. sp_HelpText for sp_HelpText – Puzzle A simple quick puzzle – do you know the answer of it? If not, go ahead and read the blog. 2008 SQL SERVER – 2008 – Step By Step Installation Guide With Images When SQL Server 2008 was newly introduced lots of people had no clue how to install SQL Server 2008 and the amount of the question which I used to receive were so much. I wrote this blog post with the spirit that this will help all the newbies to install SQL Server 2008 with the help of images. Still today this blog post has been bible for all of the people who are confused with SQL Server installation. Inline Variable Assignment I loved this feature. I have always wanted this feature to be present in SQL Server. The last time when I met developers from Microsoft SQL Server, I had talked about this feature. I think this feature saves some time but make the code more readable. Introduction to Policy Management – Enforcing Rules on SQL Server If our company policy is to create all the Stored Procedure with prefix ‘usp’ that developers should be just prevented to create Stored Procedure with any other prefix. Let us see a small tutorial how to create conditions and policy which will prevent any future SP to be created with any other prefix. 2009 Performance Counters from System Views – By Kevin Mckenna Many of you are not aware of this fact that access to performance information is readily available in SQL Server and that too without querying performance counters using a custom application or via perfmon. Till now, this fact has remained undisclosed but through this post I would like to explain you can easily access SQL Server performance counter information. Without putting much effort you will come across the system viewsys.dm_os_performance_counters. As the name suggests, this provides you easy access to the SQL Server performance counter information that is passed on to perfmon, but you can get at it via tsql. Customize Toolbar – Remove Debug Button from Toolbar I was fond of SQL Server Debugger feature in SQL Server 2000. To my utter disappointment, this feature was withdrawn from SQL Server 2005. The button of the debugger is similar to a play button and is used to run debugging commands of Visual Studio. Because of this reason, it gets very much infuriating for developers when they are developing on both – Visual Studio and SSMS. Let us now see how we can remove debugging button from SQL Server Management Studio. Effect of Normalization on Index and Performance A very interesting conversation which started from twitter. If you want to read one link this is the link I encourage you to read it. SSMS Feature – Multi-server Queries Using SQL Server Management Studio (SSMS) DBAs can now query multiple servers from one window. It is quite common for DBAs with large amount of servers to maintain and gather information from multiple SQL Servers and create report. This feature is a blessing for the DBAs, as they can now assemble all the information instantaneously without going anywhere. Query Optimizer Hint ROBUST PLAN – Question to You “ROBUST PLAN” is a kind of query hint which works quite differently than other hints. It does not improve join or force any indexes to use; it just makes sure that a query does not crash due to over the limit size of row. Let me elaborate upon it in the blog post. 2010 Do you really know the difference between various date functions available in SQL Server 2012? Here is a three part story where we explored the same with examples: Fastest Way to Restore the Database Difference Between DATETIME and DATETIME2 Difference Between DATETIME and DATETIME2 – WITH GETDATE Shrinking NDF and MDF Files – Readers’ Opinion Shrinking Database always creates performance degradation and increases fragmentation in the database. I suggest that you keep that in mind before you start reading the following comment. If you are going to say Shrinking Database is bad and evil, here I am saying it first and loud. Now, the comment of Imran is written while keeping in mind only the process showing how the Shrinking Database Operation works. Imran has already explained his understanding and requests further explanation. I have removed the Best Practices section from Imran’s comments, as there are a few corrections. 2011 Solution – Puzzle – SELECT * vs SELECT COUNT(*) This is very interesting question and I am very confident that not every one knows the answer to this question. Let me ask you again – Which will be faster SELECT* or SELECT COUNT (*) or do you think this is apples and oranges comparison. 2012 Service Broker and CAP_CPU_PERCENT – Limiting SQL Server Instances to CPU Usage In SQL Server 2012 there are a few enhancements with regards to SQL Server Resource Governor. One of the enhancement is how the resources are allocated. Let me explain you with examples. Let us understand the entire discussion with the help of three different examples. Finding Size of a Columnstore Index Using DMVs One of the very common question I often see is need of the list of columnstore index along with their size and corresponding table name. I quickly re-wrote a script using DMVs sys.indexes and sys.dm_db_partition_stats. This script gives the size of the columnstore index on disk only. I am sure there will be advanced script to retrieve details related to components associated with the columnstore index. However, I believe following script is sufficient to start getting an idea of columnstore index size. Developer Training Resources and Summary Roundup Developer Training - Importance and Significance - Part 1 In this part we discussed the importance of training in the real world. The most important and valuable resource any company is its employee. Employees who have been well-trained will be better at their jobs and produce a better product.  An employee who is well trained obviously knows more about their job and all the technical aspects. I have a very high opinion about training employees and it is the most important task. Developer Training – Employee Morals and Ethics – Part 2 In this part we discussed the most crucial components of training. Often employees are expecting the company to pay for their training and the company expresses no interest in training the employee. Quite often training expenses are the real issue for both the employee and employer. Developer Training – Difficult Questions and Alternative Perspective - Part 3 This part was the most difficult to write as I tried to address a few difficult questions and answers. Training is such a sensitive issue that many developers when not receiving chance for training think about leaving the organization. Developer Training – Various Options for Developer Training – Part 4 In this part I tried to explore a few methods and options for training. The generic feedback I received on this blog post was short and I should have explored each of the subject of the training in details. I believe there are two big buckets of training 1) Instructor Lead Training and 2) Self Lead Training. Developer Training – A Conclusive Summary- Part 5 There is no better motivation than a personal desire to learn new technology. Honestly there is nothing more personal learning. That “change is the only constant” and “adapt & overcome” are the essential lessons of life. One cannot stop the learning and resist the change. In the IT industry “ego of knowing all” and the “resistance to change” are the most challenging issues. A Quick Look at Logging and Ideas around Logging Question: What is the first thing comes to your mind when you hear the word “Logging”? Strange enough I got a different answer every single time. Let me just list what answer I got from my friends. Let us go over them one by one. Beginning Performance Tuning with SQL Server Execution Plan Solution of Puzzle – Swap Value of Column Without Case Statement Earlier this week I asked a question where I asked how to Swap Values of the column without using CASE Statement. Read here: SQL SERVER – A Puzzle – Swap Value of Column Without Case Statement. I have proposed 3 different solutions in the blog posts itself. I had requested the help of the community to come up with alternate solutions and honestly I am stunned and amazed by the qualified entries. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• 8-Puzzle Solution executes infinitely [migrated]

  - by Ashwin

  I am looking for a solution to 8-puzzle problem using the A* Algorithm. I found this project on the internet. Please see the files - proj1 and EightPuzzle. The proj1 contains the entry point for the program(the main() function) and EightPuzzle describes a particular state of the puzzle. Each state is an object of the 8-puzzle. I feel that there is nothing wrong in the logic. But it loops forever for these two inputs that I have tried : {8,2,7,5,1,6,3,0,4} and {3,1,6,8,4,5,7,2,0}. Both of them are valid input states. What is wrong with the code? Note For better viewing copy the code in a Notepad++ or some other text editor(which has the capability to recognize java source file) because there are lot of comments in the code. Since A* requires a heuristic, they have provided the option of using manhattan distance and a heuristic that calculates the number of misplaced tiles. And to ensure that the best heuristic is executed first, they have implemented a PriorityQueue. The compareTo() function is implemented in the EightPuzzle class. The input to the program can be changed by changing the value of p1d in the main() function of proj1 class. The reason I am telling that there exists solution for the two my above inputs is because the applet here solves them. Please ensure that you select 8-puzzle from teh options in the applet. EDITI gave this input {0,5,7,6,8,1,2,4,3}. It took about 10 seconds and gave a result with 26 moves. But the applet gave a result with 24 moves in 0.0001 seconds with A*. For quick reference I have pasted the the two classes without the comments : EightPuzzle import java.util.*; public class EightPuzzle implements Comparable <Object> { int[] puzzle = new int[9]; int h_n= 0; int hueristic_type = 0; int g_n = 0; int f_n = 0; EightPuzzle parent = null; public EightPuzzle(int[] p, int h_type, int cost) { this.puzzle = p; this.hueristic_type = h_type; this.h_n = (h_type == 1) ? h1(p) : h2(p); this.g_n = cost; this.f_n = h_n + g_n; } public int getF_n() { return f_n; } public void setParent(EightPuzzle input) { this.parent = input; } public EightPuzzle getParent() { return this.parent; } public int inversions() { /* * Definition: For any other configuration besides the goal, * whenever a tile with a greater number on it precedes a * tile with a smaller number, the two tiles are said to be inverted */ int inversion = 0; for(int i = 0; i < this.puzzle.length; i++ ) { for(int j = 0; j < i; j++) { if(this.puzzle[i] != 0 && this.puzzle[j] != 0) { if(this.puzzle[i] < this.puzzle[j]) inversion++; } } } return inversion; } public int h1(int[] list) // h1 = the number of misplaced tiles { int gn = 0; for(int i = 0; i < list.length; i++) { if(list[i] != i && list[i] != 0) gn++; } return gn; } public LinkedList<EightPuzzle> getChildren() { LinkedList<EightPuzzle> children = new LinkedList<EightPuzzle>(); int loc = 0; int temparray[] = new int[this.puzzle.length]; EightPuzzle rightP, upP, downP, leftP; while(this.puzzle[loc] != 0) { loc++; } if(loc % 3 == 0){ temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 1]; temparray[loc + 1] = 0; rightP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); rightP.setParent(this); children.add(rightP); }else if(loc % 3 == 1){ //add one child swaps with right temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 1]; temparray[loc + 1] = 0; rightP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); rightP.setParent(this); children.add(rightP); //add one child swaps with left temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 1]; temparray[loc - 1] = 0; leftP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); leftP.setParent(this); children.add(leftP); }else if(loc % 3 == 2){ // add one child swaps with left temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 1]; temparray[loc - 1] = 0; leftP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); leftP.setParent(this); children.add(leftP); } if(loc / 3 == 0){ //add one child swaps with lower temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 3]; temparray[loc + 3] = 0; downP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); downP.setParent(this); children.add(downP); }else if(loc / 3 == 1 ){ //add one child, swap with upper temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 3]; temparray[loc - 3] = 0; upP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); upP.setParent(this); children.add(upP); //add one child, swap with lower temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 3]; temparray[loc + 3] = 0; downP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); downP.setParent(this); children.add(downP); }else if (loc / 3 == 2 ){ //add one child, swap with upper temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 3]; temparray[loc - 3] = 0; upP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); upP.setParent(this); children.add(upP); } return children; } public int h2(int[] list) // h2 = the sum of the distances of the tiles from their goal positions // for each item find its goal position // calculate how many positions it needs to move to get into that position { int gn = 0; int row = 0; int col = 0; for(int i = 0; i < list.length; i++) { if(list[i] != 0) { row = list[i] / 3; col = list[i] % 3; row = Math.abs(row - (i / 3)); col = Math.abs(col - (i % 3)); gn += row; gn += col; } } return gn; } public String toString() { String x = ""; for(int i = 0; i < this.puzzle.length; i++){ x += puzzle[i] + " "; if((i + 1) % 3 == 0) x += "\n"; } return x; } public int compareTo(Object input) { if (this.f_n < ((EightPuzzle) input).getF_n()) return -1; else if (this.f_n > ((EightPuzzle) input).getF_n()) return 1; return 0; } public boolean equals(EightPuzzle test){ if(this.f_n != test.getF_n()) return false; for(int i = 0 ; i < this.puzzle.length; i++) { if(this.puzzle[i] != test.puzzle[i]) return false; } return true; } public boolean mapEquals(EightPuzzle test){ for(int i = 0 ; i < this.puzzle.length; i++) { if(this.puzzle[i] != test.puzzle[i]) return false; } return true; } } proj1 import java.util.*; public class proj1 { /** * @param args */ public static void main(String[] args) { int[] p1d = {1, 4, 2, 3, 0, 5, 6, 7, 8}; int hueristic = 2; EightPuzzle start = new EightPuzzle(p1d, hueristic, 0); int[] win = { 0, 1, 2, 3, 4, 5, 6, 7, 8}; EightPuzzle goal = new EightPuzzle(win, hueristic, 0); astar(start, goal); } public static void astar(EightPuzzle start, EightPuzzle goal) { if(start.inversions() % 2 == 1) { System.out.println("Unsolvable"); return; } // function A*(start,goal) // closedset := the empty set // The set of nodes already evaluated. LinkedList<EightPuzzle> closedset = new LinkedList<EightPuzzle>(); // openset := set containing the initial node // The set of tentative nodes to be evaluated. priority queue PriorityQueue<EightPuzzle> openset = new PriorityQueue<EightPuzzle>(); openset.add(start); while(openset.size() > 0){ // x := the node in openset having the lowest f_score[] value EightPuzzle x = openset.peek(); // if x = goal if(x.mapEquals(goal)) { // return reconstruct_path(came_from, came_from[goal]) Stack<EightPuzzle> toDisplay = reconstruct(x); System.out.println("Printing solution... "); System.out.println(start.toString()); print(toDisplay); return; } // remove x from openset // add x to closedset closedset.add(openset.poll()); LinkedList <EightPuzzle> neighbor = x.getChildren(); // foreach y in neighbor_nodes(x) while(neighbor.size() > 0) { EightPuzzle y = neighbor.removeFirst(); // if y in closedset if(closedset.contains(y)){ // continue continue; } // tentative_g_score := g_score[x] + dist_between(x,y) // // if y not in openset if(!closedset.contains(y)){ // add y to openset openset.add(y); // } // } // } } public static void print(Stack<EightPuzzle> x) { while(!x.isEmpty()) { EightPuzzle temp = x.pop(); System.out.println(temp.toString()); } } public static Stack<EightPuzzle> reconstruct(EightPuzzle winner) { Stack<EightPuzzle> correctOutput = new Stack<EightPuzzle>(); while(winner.getParent() != null) { correctOutput.add(winner); winner = winner.getParent(); } return correctOutput; } }

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• usb wifi dongle on ubuntu server, cannot install realtek driver RTL 8188cus

  - by Sandro Dzneladze

  I got cheap Ebay wifi dongle from HongKong, Im trying to set it up on my ubuntu server. Occasionally need to move server, so it cannot always be connected to router via lan. Anyhow, usb wifi came with a driver cd. I uploaded files to my home directory and tried to run install script (RTL 8188cus): sudo bash install.sh But I get error: Authentication requested [root] for make driver: make ARCH=x86_64 CROSS_COMPILE= -C /lib/modules/2.6.38-8-server/build M=/home/minime/RTL 8188cus/Linux/driver/rtl8192CU_linux_v2.0.1324.20110126 modules make[1]: Entering directory `/usr/src/linux-headers-2.6.38-8-server' make[1]: *** No rule to make target `8188cus/Linux/driver/rtl8192CU_linux_v2.0.1324.20110126'. Stop. make[1]: Leaving directory `/usr/src/linux-headers-2.6.38-8-server' make: *** [modules] Error 2 Compile make driver error: 2, Please check error Mesg Any ideas what Im doing wrong? There is another driver folder for linux called: RTL 81XX, which doesn't have install.sh at all! I tried to use make command, but I get: make: *** No targets specified and no makefile found. Stop. Any help? this is first time I'm installing driver from source. Im on Ubuntu 11.04 server. lsusb Bus 001 Device 002: ID 0bda:8176 Realtek Semiconductor Corp. lspci -nn 00:00.0 Host bridge [0600]: Intel Corporation N10 Family DMI Bridge [8086:a000] (rev 02) 00:02.0 VGA compatible controller [0300]: Intel Corporation N10 Family Integrated Graphics Controller [8086:a001] (rev 02) 00:1b.0 Audio device [0403]: Intel Corporation N10/ICH 7 Family High Definition Audio Controller [8086:27d8] (rev 02) 00:1c.0 PCI bridge [0604]: Intel Corporation N10/ICH 7 Family PCI Express Port 1 [8086:27d0] (rev 02) 00:1d.0 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #1 [8086:27c8] (rev 02) 00:1d.1 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #2 [8086:27c9] (rev 02) 00:1d.2 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #3 [8086:27ca] (rev 02) 00:1d.3 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #4 [8086:27cb] (rev 02) 00:1d.7 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB2 EHCI Controller [8086:27cc] (rev 02) 00:1e.0 PCI bridge [0604]: Intel Corporation 82801 Mobile PCI Bridge [8086:2448] (rev e2) 00:1f.0 ISA bridge [0601]: Intel Corporation NM10 Family LPC Controller [8086:27bc] (rev 02) 00:1f.2 IDE interface [0101]: Intel Corporation N10/ICH7 Family SATA IDE Controller [8086:27c0] (rev 02) 00:1f.3 SMBus [0c05]: Intel Corporation N10/ICH 7 Family SMBus Controller [8086:27da] (rev 02) 01:00.0 Ethernet controller [0200]: Atheros Communications Device [1969:1083] (rev c0) sudo lshw description: Desktop Computer product: To Be Filled By O.E.M. (To Be Filled By O.E.M.) vendor: To Be Filled By O.E.M. version: To Be Filled By O.E.M. serial: To Be Filled By O.E.M. width: 64 bits capabilities: smbios-2.6 dmi-2.6 vsyscall64 vsyscall32 configuration: boot=normal chassis=desktop family=To Be Filled By O.E.M. sku=To Be Filled By O.E.M. uuid=00020003-0004-0005-0006-000700080009 *-core description: Motherboard product: AD525PV3 vendor: ASRock physical id: 0 *-firmware description: BIOS vendor: American Megatrends Inc. physical id: 0 version: P1.20 date: 04/01/2011 size: 64KiB capacity: 448KiB capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb ls120boot zipboot biosbootspecification netboot *-cpu description: CPU product: Intel(R) Atom(TM) CPU D525 @ 1.80GHz vendor: Intel Corp. physical id: 4 bus info: cpu@0 version: Intel(R) Atom(TM) CPU D525 @ 1.80GHz serial: To Be Filled By O.E.M. slot: CPUSocket size: 1800MHz capacity: 1800MHz width: 64 bits clock: 200MHz capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl tm2 ssse3 cx16 xtpr pdcm movbe lahf_lm configuration: cores=2 enabledcores=2 threads=4 *-cache:0 description: L1 cache physical id: 5 slot: L1-Cache size: 48KiB capacity: 48KiB capabilities: internal write-back data *-cache:1 description: L2 cache physical id: 6 slot: L2-Cache size: 1MiB capacity: 1MiB capabilities: internal write-back unified *-memory description: System Memory physical id: c slot: System board or motherboard size: 2GiB *-bank:0 description: SODIMM DDR2 Synchronous 800 MHz (1.2 ns) product: ModulePartNumber00 vendor: Manufacturer00 physical id: 0 serial: SerNum00 slot: DIMM0 size: 2GiB width: 64 bits clock: 800MHz (1.2ns) *-bank:1 description: DIMM [empty] product: ModulePartNumber01 vendor: Manufacturer01 physical id: 1 serial: SerNum01 slot: DIMM1 *-pci description: Host bridge product: N10 Family DMI Bridge vendor: Intel Corporation physical id: 100 bus info: pci@0000:00:00.0 version: 02 width: 32 bits clock: 33MHz configuration: driver=agpgart-intel resources: irq:0 *-display description: VGA compatible controller product: N10 Family Integrated Graphics Controller vendor: Intel Corporation physical id: 2 bus info: pci@0000:00:02.0 version: 02 width: 32 bits clock: 33MHz capabilities: msi pm vga_controller bus_master cap_list rom configuration: driver=i915 latency=0 resources: irq:41 memory:fea80000-feafffff ioport:dc00(size=8) memory:e0000000-efffffff memory:fe900000-fe9fffff *-multimedia description: Audio device product: N10/ICH 7 Family High Definition Audio Controller vendor: Intel Corporation physical id: 1b bus info: pci@0000:00:1b.0 version: 02 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: driver=HDA Intel latency=0 resources: irq:43 memory:fea78000-fea7bfff *-pci:0 description: PCI bridge product: N10/ICH 7 Family PCI Express Port 1 vendor: Intel Corporation physical id: 1c bus info: pci@0000:00:1c.0 version: 02 width: 32 bits clock: 33MHz capabilities: pci pciexpress msi pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:40 ioport:e000(size=4096) memory:feb00000-febfffff ioport:80000000(size=2097152) *-network description: Ethernet interface product: Atheros Communications vendor: Atheros Communications physical id: 0 bus info: pci@0000:01:00.0 logical name: eth0 version: c0 serial: XX size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI duplex=full firmware=N/A ip=192.168.1.99 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s resources: irq:42 memory:febc0000-febfffff ioport:ec00(size=128) *-usb:0 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #1 vendor: Intel Corporation physical id: 1d bus info: pci@0000:00:1d.0 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:23 ioport:d880(size=32) *-usb:1 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #2 vendor: Intel Corporation physical id: 1d.1 bus info: pci@0000:00:1d.1 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:19 ioport:d800(size=32) *-usb:2 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #3 vendor: Intel Corporation physical id: 1d.2 bus info: pci@0000:00:1d.2 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:18 ioport:d480(size=32) *-usb:3 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #4 vendor: Intel Corporation physical id: 1d.3 bus info: pci@0000:00:1d.3 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:16 ioport:d400(size=32) *-usb:4 description: USB Controller product: N10/ICH 7 Family USB2 EHCI Controller vendor: Intel Corporation physical id: 1d.7 bus info: pci@0000:00:1d.7 version: 02 width: 32 bits clock: 33MHz capabilities: pm debug ehci bus_master cap_list configuration: driver=ehci_hcd latency=0 resources: irq:23 memory:fea77c00-fea77fff *-pci:1 description: PCI bridge product: 82801 Mobile PCI Bridge vendor: Intel Corporation physical id: 1e bus info: pci@0000:00:1e.0 version: e2 width: 32 bits clock: 33MHz capabilities: pci subtractive_decode bus_master cap_list *-isa description: ISA bridge product: NM10 Family LPC Controller vendor: Intel Corporation physical id: 1f bus info: pci@0000:00:1f.0 version: 02 width: 32 bits clock: 33MHz capabilities: isa bus_master cap_list configuration: latency=0 *-ide description: IDE interface product: N10/ICH7 Family SATA IDE Controller vendor: Intel Corporation physical id: 1f.2 bus info: pci@0000:00:1f.2 logical name: scsi0 version: 02 width: 32 bits clock: 66MHz capabilities: ide pm bus_master cap_list emulated configuration: driver=ata_piix latency=0 resources: irq:19 ioport:1f0(size=8) ioport:3f6 ioport:170(size=8) ioport:376 ioport:ff90(size=16) memory:80200000-802003ff *-disk description: ATA Disk product: WDC WD10TPVT-11U vendor: Western Digital physical id: 0.0.0 bus info: scsi@0:0.0.0 logical name: /dev/sda version: 01.0 serial: WD-WXC1A80P0314 size: 931GiB (1TB) capabilities: partitioned partitioned:dos configuration: ansiversion=5 signature=00088c47 *-volume:0 description: EXT4 volume vendor: Linux physical id: 1 bus info: scsi@0:0.0.0,1 logical name: /dev/sda1 logical name: /media/private version: 1.0 serial: 042daf2d-350c-4640-a76a-4554c9d98c59 size: 300GiB capacity: 300GiB capabilities: primary journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2011-11-06 11:05:03 filesystem=ext4 label=Private lastmountpoint=/media/private modified=2012-04-13 20:01:16 mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered mounted=2012-04-13 20:01:16 state=mounted *-volume:1 description: Extended partition physical id: 2 bus info: scsi@0:0.0.0,2 logical name: /dev/sda2 size: 625GiB capacity: 625GiB capabilities: primary extended partitioned partitioned:extended *-logicalvolume:0 description: Linux filesystem partition physical id: 5 logical name: /dev/sda5 logical name: /media/storage capacity: 600GiB configuration: mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered state=mounted *-logicalvolume:1 description: Linux filesystem partition physical id: 6 logical name: /dev/sda6 logical name: /media/dropbox capacity: 24GiB configuration: mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered state=mounted *-volume:2 description: EXT4 volume vendor: Linux physical id: 3 bus info: scsi@0:0.0.0,3 logical name: /dev/sda3 logical name: /media/www version: 1.0 serial: 9b0a27b4-05d8-40d5-bfc7-4aeba198db7b size: 2570MiB capacity: 2570MiB capabilities: primary journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2011-11-06 11:05:11 filesystem=ext4 label=www lastmountpoint=/media/www modified=2012-04-15 11:31:12 mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered mounted=2012-04-15 11:31:12 state=mounted *-volume:3 description: Linux swap volume physical id: 4 bus info: scsi@0:0.0.0,4 logical name: /dev/sda4 version: 1 serial: 6ed1130e-3aad-4fa6-890b-77e729121e3b size: 4098MiB capacity: 4098MiB capabilities: primary nofs swap initialized configuration: filesystem=swap pagesize=4096 *-serial UNCLAIMED description: SMBus product: N10/ICH 7 Family SMBus Controller vendor: Intel Corporation physical id: 1f.3 bus info: pci@0000:00:1f.3 version: 02 width: 32 bits clock: 33MHz configuration: latency=0 resources: ioport:400(size=32) *-scsi physical id: 1 bus info: usb@1:4 logical name: scsi2 capabilities: emulated scsi-host configuration: driver=usb-storage *-disk description: SCSI Disk physical id: 0.0.0 bus info: scsi@2:0.0.0 logical name: /dev/sdb size: 3864MiB (4051MB) capabilities: partitioned partitioned:dos configuration: signature=000b4c55 *-volume description: EXT4 volume vendor: Linux physical id: 1 bus info: scsi@2:0.0.0,1 logical name: /dev/sdb1 logical name: / version: 1.0 serial: 33926e39-4685-4f63-b83c-f2a67824b69a size: 3862MiB capacity: 3862MiB capabilities: primary bootable journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2011-10-11 14:03:46 filesystem=ext4 lastmountpoint=/ modified=2012-03-19 11:47:29 mount.fstype=ext4 mount.options=rw,noatime,errors=remount-ro,barrier=1,data=ordered mounted=2012-04-15 11:31:11 state=mounted rfkill list all Doesnt show anything! dmesg | grep -i firmware [ 0.715481] pci 0000:00:1f.0: [Firmware Bug]: TigerPoint LPC.BM_STS cleared

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• Java Refuses to Start - Could not reserve enough space for object heap

  - by Randyaa

  Background We have a pool of aproximately 20 linux blades. Some are running Suse, some are running Redhat. ALL share NAS space which contains the following 3 folders: /NAS/app/java - a symlink that points to an installation of a Java JDK. Currently version 1.5.0_10 /NAS/app/lib - a symlink that points to a version of our application. /NAS/data - directory where our output is written All our machines have 2 processors (hyperthreaded) with 4gb of physical memory and 4gb of swap space. We limit the number of 'jobs' each machine can process at a given time to 6 (this number likely needs to change, but that does not enter into the current problem so please ignore it for the time being). Some of our jobs set a Max Heap size of 512mb, some others reserve a Max Heap size of 2048mb. Again, we realize we could go over our available memory if 6 jobs started on the same machine with the heap size set to 2048, but to our knowledge this has not yet occurred. The Problem Once and a while a Job will fail immediately with the following message: Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. We used to chalk this up to too many jobs running at the same time on the same machine. The problem happened infrequently enough (MAYBE once a month) that we'd just restart it and everything would be fine. The problem has recently gotten much worse. All of our jobs which request a max heap size of 2048m fail immediately almost every time and need to get restarted several times before completing. We've gone out to individual machines and tried executing them manually with the same result. Debugging It turns out that the problem only exists for our SuSE boxes. The reason it has been happening more frequently is becuase we've been adding more machines, and the new ones are SuSE. 'cat /proc/version' on the SuSE boxes give us: Linux version 2.6.5-7.244-bigsmp (geeko@buildhost) (gcc version 3.3.3 (SuSE Linux)) #1 SMP Mon Dec 12 18:32:25 UTC 2005 'cat /proc/version' on the RedHat boxes give us: Linux version 2.4.21-32.0.1.ELsmp ([email protected]) (gcc version 3.2.3 20030502 (Red Hat Linux 3.2.3-52)) #1 SMP Tue May 17 17:52:23 EDT 2005 'uname -a' gives us the following on BOTH types of machines: UTC 2005 i686 i686 i386 GNU/Linux No jobs are running on the machine, and no other processes are utilizing much memory. All of the processes currently running might be using 100mb total. 'top' currently shows the following: Mem: 4146528k total, 3536360k used, 610168k free, 132136k buffers Swap: 4194288k total, 0k used, 4194288k free, 3283908k cached 'vmstat' currently shows the following: procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 610292 132136 3283908 0 0 0 2 26 15 0 0 100 0 If we kick off a job with the following command line (Max Heap of 1850mb) it starts fine: java/bin/java -Xmx1850M -cp helloworld.jar HelloWorld Hello World If we bump up the max heap size to 1875mb it fails: java/bin/java -Xmx1875M -cp helloworld.jar HelloWorld Error occurred during initialization of VM Could not reserve enough space for object heap Could not create the Java virtual machine. It's quite clear that the memory currently being used is for Buffering/Caching and that's why so little is being displayed as 'free'. What isn't clear is why there is a magical 1850mb line where anything higher means Java can't start. Any explanations would be greatly appreciated.

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• cannot make ubuntu 64-bit v12.04 install work

  - by honestann

  I decided it was time to update my ubuntu (single boot) computer from 64-bit v10.04 to 64-bit v12.04. Unfortunately, for some reason (or reasons) I just can't make it work. Note that I am attempting a fresh install of 64-bit v12.04 onto a new 3TB hard disk, not an upgrade of the 1TB hard disk that contains my working 64-bit v10.04 installation. To perform the attempted install of v12.04 I unplug the SATA cable from the 1TB drive and plug it into the 3TB drive (to avoid risking damage to my working v10.04 installation). I downloaded the ubuntu 64-bit v12.04 install DVD ISO file (~1.6 GB) from the ubuntu releases webpage and burned it onto a DVD. I have downloaded the DVD ISO file 3 times and burned 3 of these installation DVDs (twice with v10.04 and once with my winxp64 system), but none of them work. I run the "check disk" on the DVDs at the beginning of the installation process to assure the DVD is valid. When installation completes and the system boots the 3TB drive, it reports "unknown filesystem". After installation on the 250GB drives, the system boots up fine. During every install I plug the same SATA cable (sda) into only one disk drive (the 3TB or one of the 250GB drives) and leave the other disk drives unconnected (for simplicity). It is my understanding that 64-bit ubuntu (and 64-bit linux in general) has no problem with 3TB disk drives. In the BIOS I have tried having EFI set to "enabled" and "auto" with no apparent difference (no success). I never bothered setting the BIOS to "non-EFI". I have tried partitioning the drive in a few ways to see if that makes a difference, but so far it has not mattered. Typically I manually create partitions something like this: 8GB /boot ext4 8GB swap 3TB / ext4 But I've also tried the following, just in case it matters: 8GB boot efi 8GB swap 8GB /boot ext4 3TB / ext4 Note: In the partition dialog I specify bootup on the same drive I am partitioning and installing ubuntu v12.04 onto. It is a VERY DANGEROUS FACT that the default for this always comes up with the wrong drive (some other drive, generally the external drive). Unless I'm stupid or misunderstanding something, this is very wrong and very dangerous default behavior. Note: If I connect the SATA cable to the 1TB drive that has been my ubuntu 64-bit v10.04 system drive for the past 2 years, it boots up and runs fine. I guess there must be a log file somewhere, and maybe it gives some hints as to what the problem is. I should be able to boot off the 1TB drive with the 3TB drive connected as a secondary (non-boot) drive and get the log file, assuming there is one and someone tells me the name (and where to find it if the name is very generic). After installation on the 3TB drive completes and the system reboots, the following prints out on a black screen: Loading Operating System ... Boot from CD/DVD : Boot from CD/DVD : error: unknown filesystem grub rescue> Note: I have two DVD burners in the system, hence the duplicate line above. Note: I install and boot 64-bit ubuntu v12.04 on both of my 250GB in this same system, but still cannot make the 3TB drive boot. Sigh. Any ideas? ========== motherboard == gigabyte 990FXA-UD7 CPU == AMD FX-8150 8-core bulldozer @ 3.6 GHz RAM == 8GB of DDR3 in 2 sticks (matched pair) HDD == seagate 3TB SATA3 @ 7200 rpm (new install 64-bit v12.04 FAILS) HDD == seagate 1TB SATA3 @ 7200 rpm (64-bit v10.04 WORKS for two years) HDD == seagate 250GB SATA2 @ 7200 rpm (new install 64-bit v12.04 WORKS) HDD == seagate 250GB SATA2 @ 7200 rpm (new install 64-bit v12.04 WORKS) GPU == nvidia GTX-285 ??? == no overclocking or other funky business USB == external seagate 2TB HDD for making backups DVD == one bluray burner (SATA) DVD == one DVD burner (SATA) 64-bit ubuntu v10.04 has booted and run fine on the seagate 1TB drive for 2 years.

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• How can I change mouse keymapping

  - by zuberuber

  I have Razer DeathAdder(left handed edition) and A4Tech wireless mouse. My problem is I don't know how to change wireless mouse keymapping(swaping left/right click). Can somebody guide me how to do such thing? List of my devices: ? Virtual core pointer id=2 [master pointer (3)] ? ? Virtual core XTEST pointer id=4 [slave pointer (2)] ? ? Logitech Unifying Device. Wireless PID:4004 id=8 [slave pointer (2)] ? ? Razer Razer DeathAdder id=11 [slave pointer (2)] ? ? A4TECH USB Device id=12 [slave pointer (2)] ? ? A4TECH USB Device id=13 [slave pointer (2)] ? Virtual core keyboard id=3 [master keyboard (2)] ? Virtual core XTEST keyboard id=5 [slave keyboard (3)] ? Power Button id=6 [slave keyboard (3)] ? Power Button id=7 [slave keyboard (3)] ? Logitech USB Keyboard id=9 [slave keyboard (3)] ? Logitech USB Keyboard id=10 [slave keyboard (3)] This is my Razer xinput: Device 'Razer Razer DeathAdder': Device Enabled (121): 1 Coordinate Transformation Matrix (123): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000 Device Accel Profile (246): 0 Device Accel Constant Deceleration (247): 5.000000 Device Accel Adaptive Deceleration (248): 1.000000 Device Accel Velocity Scaling (249): 10.000000 Device Product ID (240): 5426, 22 Device Node (241): "/dev/input/event4" Evdev Axis Inversion (250): 0, 0 Evdev Axes Swap (252): 0 Axis Labels (253): "Rel X" (131), "Rel Y" (132), "Rel Vert Wheel" (274) Button Labels (254): "Button Left" (124), "Button Middle" (125), "Button Right" (126), "Button Wheel Up" (127), "Button Wheel Down" (128), "Button Horiz Wheel Left" (129), "Button Horiz Wheel Right" (130), "Button Side" (269), "Button Extra" (270), "Button Forward" (271), "Button Back" (272), "Button Task" (273), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243) Evdev Middle Button Emulation (255): 0 Evdev Middle Button Timeout (256): 50 Evdev Third Button Emulation (257): 0 Evdev Third Button Emulation Timeout (258): 1000 Evdev Third Button Emulation Button (259): 3 Evdev Third Button Emulation Threshold (260): 20 Evdev Wheel Emulation (261): 0 Evdev Wheel Emulation Axes (262): 0, 0, 4, 5 Evdev Wheel Emulation Inertia (263): 10 Evdev Wheel Emulation Timeout (264): 200 Evdev Wheel Emulation Button (265): 4 Evdev Drag Lock Buttons (266): 0 And this is my wireless mouse xinput: Device 'A4TECH USB Device': Device Enabled (121): 1 Coordinate Transformation Matrix (123): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000 Device Accel Profile (246): 0 Device Accel Constant Deceleration (247): 1.000000 Device Accel Adaptive Deceleration (248): 1.000000 Device Accel Velocity Scaling (249): 10.000000 Device Product ID (240): 2522, 1359 Device Node (241): "/dev/input/event16" Evdev Axis Inversion (250): 0, 0 Evdev Axes Swap (252): 0 Axis Labels (253): "Rel X" (131), "Rel Y" (132), "Rel Horiz Wheel" (245), "Rel Vert Wheel" (274) Button Labels (254): "Button Left" (124), "Button Middle" (125), "Button Right" (126), "Button Wheel Up" (127), "Button Wheel Down" (128), "Button Horiz Wheel Left" (129), "Button Horiz Wheel Right" (130), "Button Side" (269), "Button Extra" (270), "Button Forward" (271), "Button Back" (272), "Button Task" (273), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243), "Button Unknown" (243) Evdev Middle Button Emulation (255): 0 Evdev Middle Button Timeout (256): 50 Evdev Third Button Emulation (257): 0 Evdev Third Button Emulation Timeout (258): 1000 Evdev Third Button Emulation Button (259): 3 Evdev Third Button Emulation Threshold (260): 20 Evdev Wheel Emulation (261): 0 Evdev Wheel Emulation Axes (262): 0, 0, 4, 5 Evdev Wheel Emulation Inertia (263): 10 Evdev Wheel Emulation Timeout (264): 200 Evdev Wheel Emulation Button (265): 4 Evdev Drag Lock Buttons (266): 0

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• help: cannot make ubuntu 64-bit v12.04 install work

  - by honestann

  I decided it was time to update my ubuntu (single boot) computer from 64-bit v10.04 to 64-bit v12.04. Unfortunately, for some reason (or reasons) I just can't make it work. Note that I am attempting a fresh install of 64-bit v12.04 onto a new 3TB hard disk, not an upgrade of the 1TB hard disk that has contained my 64-bit v10.04 installation. To perform the attempted install of v12.04 I unplug the SATA cable from the 1TB drive and plug it into the 3TB drive (to avoid risking damage to my working v10.04 installation). I downloaded the ubuntu 64-bit v12.04 install DVD ISO file (~1.6 GB) from the ubuntu releases webpage and burned it onto a DVD. I have downloaded the DVD ISO file 3 times and burned 3 of these installation DVDs (twice with v10.04 and once with my winxp64 system), but none of them work. I run the "check disk" on the DVDs at the beginning of the installation process to assure the DVD is valid. I also tried to install on two older 250GB seagate drives in the same computer. During every attempt I plug the same SATA cable (sda) into only one disk drive (the 3TB or one of the 250GB drives) and leave the other disk drives unconnected (for simplicity). Installation takes about 30 minutes on the 250GB drives, and about 60 minutes on the 3TB drive - not sure why. When I install on the 250GB drives, the install process finishes, the computer reboots (after the install DVD is removed), but I get a grub error 15. It is my understanding that 64-bit ubuntu (and 64-bit linux in general) has no problem with 3TB disk drives. In the BIOS I have tried having EFI set to "enabled" and "auto" with no apparent difference (no success). I have tried partitioning the drive in a few ways to see if that makes a difference, but so far it has not mattered. Typically I manually create partitions something like this: 8GB swap 8GB /boot ext4 3TB / ext4 But I've also tried the following, just in case it matters: 100MB boot efi 8GB swap 8GB /boot ext4 3TB / ext4 Note: In the partition dialog I specify bootup on the same drive I am partitioning and installing ubuntu v12.04 onto. It is a VERY DANGEROUS FACT that the default for this always comes up with the wrong drive (some other drive, generally the external drive). Unless I'm stupid or misunderstanding something, this is very wrong and very dangerous default behavior. Note: If I connect the SATA cable to the 1TB drive that has been my ubuntu 64-bit v10.04 system drive for the past 2 years, it boots up and runs fine. I guess there must be a log file somewhere, and maybe it gives some hints as to what the problem is. I should be able to boot off the 1TB drive with the 3TB drive connected as a secondary (non-boot) drive and get the log file, assuming there is one and someone tells me the name (and where to find it if the name is very generic). After installation on the 3TB drive completes and the system reboots, the following prints out on a black screen: Loading Operating System ... Boot from CD/DVD : Boot from CD/DVD : error: unknown filesystem grub rescue Note: I have two DVD burners in the system, hence the duplicate line above. The same install and reboot on the 250GB drives generates "grub error 15". Sigh. Any ideas? ========== motherboard == gigabyte 990FXA-UD7 CPU == AMD FX-8150 8-core bulldozer @ 3.6 GHz RAM == 8GB of DDR3 in 2 sticks (matched pair) HDD == seagate 3TB SATA3 @ 7200 rpm (new install 64-bit v12.04) HDD == seagate 1TB SATA3 @ 7200 rpm (current install 64-bit v10.04) GPU == nvidia GTX-285 ??? == no overclocking or other funky business USB == external seagate 2TB HDD for making backups DVD == one bluray burner (SATA) DVD == one DVD burner (SATA) The current ubuntu 64-bit v10.04 system boots and runs fine on a seagate 1TB.

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• Ubuntu 12.04 Bootloader failed to install

  - by Chris

  Sorry about the excessively long question, but I figured giving more information would be better. I recently bought a new desktop for myself, running Windows 7. It has two hard drives, and I wanted to install Ubuntu on a small partition on the second hard drive. I created 25GB "free space" in Windows and ran a LiveCD install. I wanted to select the install options myself but accidentally selected "Install alongside Windows 7," but it seemed to pick up the free space and installed itself there as I wanted it to. However, I was told that the bootloader installation had failed. I chose to "Cancel installation," leaving my computer unable to boot. I wiped my computer and reinstalled Windows. After that, I tried installing Ubuntu through Windows using WUBI, once using files from my LiveCD and once downloading everything again. Both times the install succeeded, but both times when I restarted and tried to load Ubuntu, it gave me an error - wubildr.mbr was corrupt or missing. I checked in Windows - it was indeed present on the C:\ drive. I went back to the LiveCD installation, this time going the custom options route. I assigned 16GB to an Ext4 journaling file system and 10GB to a swap file. I got the same bootloader error as before. Being prompted to select a different partition to install the bootloader to, I first tried the partition Ubuntu was installed on. A window came up saying that the install had succeeded, but a second window gave me the same error and choices as before. I went through every single option it gave me, including the Windows partition and the hard drives themselves (dev/sda, dev/sdb). Same result. I then chose to not install a bootloader. Windows still works fine, and I assume Ubuntu has installed but is unbootable. Knowing that my computer could potentially brick itself again - and, this time around, with a lot of data to lose and hassle to go through if I mess it up - I really don't want to do anything without some advice. So I'll ask this: a) Why did the bootloader fail to install? Can I fix the error and install Ubuntu fresh? b) Is there any way to get around the error, install the bootloader, and point it towards an existing installation of Ubuntu? c) Is there a quicker and easier solution I might have missed? EDIT: Thanks for the tip, AthloX. After testing the liveCD in Virtualbox with no installation problems, I looked around for some alternate bootloaders but had no success. I attempted another install, which installed the bootloader and Ubuntu just fine but bricked Windows 7. I wiped both hard disks clean, including some "System Reserved" partitions I hadn't noticed before, before re-installing Windows 7 on one hard drive and immediately afterwards installing Ubuntu on the other. Now the computer boots into Windows, but I can pop into the BIOS at startup to boot into Ubunbtu via it's bootloader, and I'm guessing it'll only take a bit of poking at the BIOS to swap the load order. Many thanks!

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• Must go through Windows Boot Loader to get to Grub

  - by Zach

  I just installed a fresh copy of Precise alongside Windows 7. I have to separate 750GB hard drives; /dev/sda holds the Windows partitions and /dev/sdb holds the Ubuntu partitions. Other than that, these are fresh installs of both Windows 7 and Ubuntu 12.04. Whenever I boot, Grub doesn't load, instead it goes to a black screen with a single blinking (horizontal bar) cursor in the top right corner. However, if I boot, hit escape right as the BIOS/POST screen finishes up, see the Windows Boot Loader and hit escape to make it go back to the BIOS screen. After the BIOS screen, grub shows up and everything functions normally; I can boot into Ubuntu or Win7. I don't want to have to do the Escape, Escape, Wait, Boot trick every time. I have no idea what would be wrong or what information I could give you guys to help diagnose. I have run a sudo update-grub and it found everything normally. I tried adding nomodeset flag in the /etc/default/grub line GRUB_CMDLINE_LINUX_DEFAULT which searching around made me think might work. Thoughts on what I could do to fix this? EDIT: I've tried changing the boot order so that both drives in the BIOS (both are labeled as "Internal HDD") have had a try booting first. I think the problem may be that every time I boot, the BIOS boot order is different... and I have to reset it. It seems to not be stable... but I'm not sure how to go about fixing that either. The machine has both traditional BIOS and UEFI. It came standard in "Legacy" mode; so it is currently set to boot through Legacy mode. I've reinstalled Ubuntu now, and now if I hit escape at the end of the BIOS/POST startup screen, it takes me to GRUB menu. Otherwise it automatically loads Windows. It seems like GRUB is now the acting bootloader, it just doesn't automatically start that unless I ask it to open a bootloader. In my other machines, it has always automatically started at the end of BIOS/POST. EDIT2: Using gparted, I just looked at my partitions, it would seem that my linux-swap partition is currently flagged as the boot partition for my Ubuntu install. I currently only have 2 partitions: one of "ext4" with a mount point of "/" and flag " "; and the "linux-swap" with mount point " " and flag "boot." If I change the boot flag to be on "/," it does not reliably solve the problem. After 10 boots: 2 Booted successfully to GRUB 5 Booted directly to Windows 7 3 booted to the black screen with the cursor and hung there Further research makes me think this is an issue of the BIOS not reliably booting hard drives in the same order or not finding both hard drives. If I ask it to create a "boot menu" sometimes it has 2 entries for "Internal HDD," sometimes 1. Also the list it creates changes order every time I bring it up; so it is not following a consistent boot sequence. Will report back if this is not an issue with GRUB.

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• disks not ready in array causes mdadm to force initramfs shell

  - by RaidPinata

  Okay, this is starting to get pretty frustrating. I've read most of the other answers on this site that have anything to do with this issue but I'm still not getting anywhere. I have a RAID 6 array with 10 devices and 1 spare. The OS is on a completely separate device. At boot only three of the 10 devices in the raid are available, the others become available later in the boot process. Currently, unless I go through initramfs I can't get the system to boot - it just hangs with a blank screen. When I do boot through recovery (initramfs), I get a message asking if I want to assemble the degraded array. If I say no and then exit initramfs the system boots fine and my array is mounted exactly where I intend it to. Here are the pertinent files as near as I can tell. Ask me if you want to see anything else. # mdadm.conf # # Please refer to mdadm.conf(5) for information about this file. # # by default (built-in), scan all partitions (/proc/partitions) and all # containers for MD superblocks. alternatively, specify devices to scan, using # wildcards if desired. #DEVICE partitions containers # auto-create devices with Debian standard permissions # CREATE owner=root group=disk mode=0660 auto=yes # automatically tag new arrays as belonging to the local system HOMEHOST <system> # instruct the monitoring daemon where to send mail alerts MAILADDR root # definitions of existing MD arrays # This file was auto-generated on Tue, 13 Nov 2012 13:50:41 -0700 # by mkconf $Id$ ARRAY /dev/md0 level=raid6 num-devices=10 metadata=1.2 spares=1 name=Craggenmore:data UUID=37eea980:24df7b7a:f11a1226:afaf53ae Here is fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> # / was on /dev/sdc2 during installation UUID=3fa1e73f-3d83-4afe-9415-6285d432c133 / ext4 errors=remount-ro 0 1 # swap was on /dev/sdc3 during installation UUID=c4988662-67f3-4069-a16e-db740e054727 none swap sw 0 0 # mount large raid device on /data /dev/md0 /data ext4 defaults,nofail,noatime,nobootwait 0 0 output of cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid6 sda[0] sdd[10](S) sdl[9] sdk[8] sdj[7] sdi[6] sdh[5] sdg[4] sdf[3] sde[2] sdb[1] 23441080320 blocks super 1.2 level 6, 512k chunk, algorithm 2 [10/10] [UUUUUUUUUU] unused devices: <none> Here is the output of mdadm --detail --scan --verbose ARRAY /dev/md0 level=raid6 num-devices=10 metadata=1.2 spares=1 name=Craggenmore:data UUID=37eea980:24df7b7a:f11a1226:afaf53ae devices=/dev/sda,/dev/sdb,/dev/sde,/dev/sdf,/dev/sdg,/dev/sdh,/dev/sdi,/dev/sdj,/dev/sdk,/dev/sdl,/dev/sdd Please let me know if there is anything else you think might be useful in troubleshooting this... I just can't seem to figure out how to change the boot process so that mdadm waits until the drives are ready to build the array. Everything works just fine if the drives are given enough time to come online. edit: changed title to properly reflect situation

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• Failed to install GRUB on a separate '/boot' partition on a fake RAID 0 (12.04LTS)

  - by gerben

  I'm having some problems getting GRUB configured for Ubuntu 12.04LTS on a fake RAID 0. I can either get the GRUB rescue prompt at startup, or just a GRUB prompt but I cannot boot to Ubuntu manually. How can I configure the GRUB to actually use the Ubuntu install? The steps taken: Installing Ubuntu on fake raid The Ubuntu installer cannot install Ubuntu on the drive. After defining the partitions to use it fails with "Error: ???", pressing OK terminates the installer. Therefore, I used GParted to configure the partitions: /dev/mapper/sil_agadaccfacbg : (the RAID configuration, created partition): /dev/mapper/sil_agadaccfacbg1:ext2, 200MiB, (with 'boot' flag) /dev/mapper/sil_agadaccfacbg3:ext2, 67.75GiB, (which will contain Ubuntu) /dev/mapper/sil_agadaccfacbg2:extended, 1.00GiB, (for swap) Contains: /dev/mapper/sil_agadaccfacbg5: unknown Because of the fake-RAID, I already mounted the destination partitions before running the Ubuntu installer: > mkdir /mnt/boot > sudo mount /dev/mapper/sil_agadaccfacbg1 /mnt/boot > mkdir /mnt/ubuntu > sudo mount /dev/mapper/sil_agadaccfacbg3 /mnt/ubuntu In the installer I chose the following partition usage: /dev/mapper/sil_agadaccfacbg1 ext2, mount at /boot (209MB) /dev/mapper/sil_agadaccfacbg3 ext2, mount at / (72751MB) /dev/mapper/sil_agadaccfacbg5 swap Device for boot loader installation: /dev/mapper/sil_agadaccfacbg, linux device-mapper (striped) (74.0GB) This will install Ubuntu, but will fail to install GRUB (it seems to use /dev/sda no matter which one I choose) Installing GRUB with dpkg-reconfigure I followed this guide, but adapted it for two partitions: sudo mount /dev/mapper/sil_agadaccfacbg3 /mnt/ubuntu sudo mount --bind /dev /mnt/ubuntu/dev sudo mount --bind /proc /mnt/ubuntu/proc sudo mount --bind /sys /mnt/ubuntu/sys sudo mount /dev/mapper/sil_agadaccfacbg1 /mnt/boot sudo mount --bind /boot /mnt/boot sudo chroot /mnt/ubuntu dpkg-reconfigure grub-pc However, it does not ask where to install GRUB (I should choose /dev/mapper/sil_agadaccfacbg somewhere..) After reboot I get the GRUB rescue prompt with message no such device Installing GRUB with grub-install After the same mount commands as above, I continued with: > sudo grub-install --root-directory=/mnt/boot /dev/mapper/sil_agadaccfacbg This gives the following message: /usr/sbin/grub-probe: error: cannot find a device for /mnt/boot/boot/grub (is /dev mounted?) It does succeed when mounting just the boot partition : sudo mount /dev/mapper/sil_agadaccfacbg1 /mnt sudo grub-install --root-directory=/mnt/ /dev/mapper/sil_agadaccfacbg This finishes with: Installation finished. No error reported. After reboot I get the GRUB console, with welcome text. Attempting to manually start Ubuntu: ls (hd0) (hd0,msdos3) : (Ubuntu install partition) (hd0,msdos1) : (Ubuntu boot partition) (hd1) (hd1,msdos1) : (Ubuntu live USB) ls (hd0,msdos3)/ contains: - vmlinuz - lib/ - tmp/ - initrd.img - mnt/ - var/ - proc/ - boot/ - root/ - etc/ - run/ - media/ - sbin/ - bin/ - selinux/ - dev/ - srv/ - home/ - sys/ ls (hd0,msdos1)/ contains: -grub/ -boot/ -initrd.img-3.8.0-29-generic -vmlinuz-3.8.0.29-generic -config-3.8 linux (hd0,msdos3)/vmlinuz This returns "error: out of disk" Installing GRUB on Ubuntu partition with grub-install > sudo mount /dev/mapper/sil_agadaccfacbg3 /mnt > sudo grub-install --root-directory=/mnt/ /dev/mapper/sil_agadaccfacbg This finishes with message: > Installation finished. No error reported. After reboot get the message "error: out of disk" and the GRUB rescue prompt. Configuring GRUB with grub-mkconfig Attempting to run grub-mkconfig with different destinations results in the same message: /usr/sbin/grub-probe: error: cannot find a device for / (is /dev mounted?). Remarks: Initially I didn't use a separate /boot partition, but the GRUB install then also failed. Because some mention that a small partition at the beginning of the drive is necessary on old machines, I retried with a /boot partition This is a single boot (no other OS's installed/used)

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• Java Runtime.getRuntime().exec() alternatives

  - by twilbrand

  I have a collection of webapps that are running under tomcat. Tomcat is configured to have as much as 2 GB of memory using the -Xmx argument. Many of the webapps need to perform a task that ends up making use of the following code: Runtime runtime = Runtime.getRuntime(); Process process = runtime.exec(command); process.waitFor(); ... The issue we are having is related to the way that this "child-process" is getting created on Linux (Redhat 4.4 and Centos 5.4). It's my understanding that an amount of memory equal to the amount tomcat is using needs to be free in the pool of physical (non-swap) system memory initially for this child process to be created. When we don't have enough free physical memory, we are getting this: java.io.IOException: error=12, Cannot allocate memory at java.lang.UNIXProcess.<init>(UNIXProcess.java:148) at java.lang.ProcessImpl.start(ProcessImpl.java:65) at java.lang.ProcessBuilder.start(ProcessBuilder.java:452) ... 28 more My questions are: 1) Is it possible to remove the requirement for an amount of memory equal to the parent process being free in the physical memory? I'm looking for an answer that allows me to specify how much memory the child process gets or to allow java on linux to access swap memory. 2) What are the alternatives to Runtime.getRuntime().exec() if no solution to #1 exists? I could only think of two, neither of which is very desirable. JNI (very un-desirable) or rewriting the program we are calling in java and making it it's own process that the webapp communicates with somehow. There has to be others. 3) Is there another side to this problem that I'm not seeing that could potentially fix it? Lowering the amount of memory used by tomcat is not an option. Increasing the memory on the server is always an option, but seems like more a band-aid. Servers are running java 6.

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• How to solve "java.io.IOException: error=12, Cannot allocate memory" calling Runtime#exec()?

  - by Andrea Francia

  On my system I can't run a simple Java application that start a process. I don't know how to solve. Could you give me some hints how to solve? The program is: [root@newton sisma-acquirer]# cat prova.java import java.io.IOException; public class prova { public static void main(String[] args) throws IOException { Runtime.getRuntime().exec("ls"); } } The result is: [root@newton sisma-acquirer]# javac prova.java && java -cp . prova Exception in thread "main" java.io.IOException: Cannot run program "ls": java.io.IOException: error=12, Cannot allocate memory at java.lang.ProcessBuilder.start(ProcessBuilder.java:474) at java.lang.Runtime.exec(Runtime.java:610) at java.lang.Runtime.exec(Runtime.java:448) at java.lang.Runtime.exec(Runtime.java:345) at prova.main(prova.java:6) Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory at java.lang.UNIXProcess.<init>(UNIXProcess.java:164) at java.lang.ProcessImpl.start(ProcessImpl.java:81) at java.lang.ProcessBuilder.start(ProcessBuilder.java:467) ... 4 more Configuration of the system: [root@newton sisma-acquirer]# java -version java version "1.6.0_0" OpenJDK Runtime Environment (IcedTea6 1.5) (fedora-18.b16.fc10-i386) OpenJDK Client VM (build 14.0-b15, mixed mode) [root@newton sisma-acquirer]# cat /etc/fedora-release Fedora release 10 (Cambridge) EDIT: Solution This solves my problem, I don't know exactly why: echo 0 /proc/sys/vm/overcommit_memory Up-votes for who is able to explain :) Additional informations, top output: top - 13:35:38 up 40 min, 2 users, load average: 0.43, 0.19, 0.12 Tasks: 129 total, 1 running, 128 sleeping, 0 stopped, 0 zombie Cpu(s): 1.5%us, 0.5%sy, 0.0%ni, 94.8%id, 3.2%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1033456k total, 587672k used, 445784k free, 51672k buffers Swap: 2031608k total, 0k used, 2031608k free, 188108k cached Additional informations, free output: [root@newton sisma-acquirer]# free total used free shared buffers cached Mem: 1033456 588548 444908 0 51704 188292 -/+ buffers/cache: 348552 684904 Swap: 2031608 0 2031608

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• Lisp Style question label local functions or not?

  - by Andrew Myers

  I was wondering if there is a standard practice regarding the use of labels in Lisp. I've been messing around with a Lisp implementation of the algorithm described in the first answer here http://stackoverflow.com/questions/352203/generating-permutations-lazily My current version uses labels to break out portions of functionality. (defun next-permutation (pmute) (declare (vector pmute)) (let ((len (length pmute))) (if (> len 2) (labels ((get-pivot () (do ((pivot (1- len) (1- pivot))) ((or (= pivot 0) (< (aref pmute (1- pivot)) (aref pmute pivot))) pivot))) (get-swap (pivot) (let ((swp (1- len))) (loop for i from (1- len) downto pivot do (if (or (and (> (aref pmute i) (aref pmute (1- pivot))) (< (aref pmute i) (aref pmute swp))) (< (aref pmute swp) (aref pmute (1- pivot)))) (setf swp i))) swp)) (next (swp pivot) (rotatef (aref pmute (1- pivot)) (aref pmute swp)) (reverse-vector pmute pivot (1- len)))) (let ((piv (get-pivot))) (if (> piv 0) (next (get-swap piv) piv) nil)))))) Since each label is only called once I was wondering if this is considered bad practice since the only reason to do it in this case is for aesthetic reasons. I would argue that the current version with labels is clearer but that may go against common wisdom that I'm not aware of, being new to Lisp.

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• What are the primitive Forth operators?

  - by Barry Brown

  I'm interested in implementing a Forth system, just so I can get some experience building a simple VM and runtime. When starting in Forth, one typically learns about the stack and its operators (DROP, DUP, SWAP, etc.) first, so it's natural to think of these as being among the primitive operators. But they're not. Each of them can be broken down into operators that directly manipulate memory and the stack pointers. Later one learns about store (!) and fetch (@) which can be used to implement DUP, SWAP, and so forth (ha!). So what are the primitive operators? Which ones must be implemented directly in the runtime environment from which all others can be built? I'm not interested in high-performance; I want something that I (and others) can learn from. Operator optimization can come later. (Yes, I'm aware that I can start with a Turing machine and go from there. That's a bit extreme.) Edit: What I'm aiming for is akin to bootstrapping an operating system or a new compiler. What do I need do implement, at minimum, so that I can construct the rest of the system out of those primitive building blocks? I won't implement this on bare hardware; as an educational exercise, I'd write my own minimal VM.

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• Optimize Use of Ramdisk for Eclipse Development

  - by Eric J.

  We're developing Java/SpringSource applications with Eclipse on 32-bit Vista machines with 4GB RAM. The OS exposes roughly 3.3GB of RAM due to reservations for hardware etc. in the virtual address space. I came across several Ramdisk drivers that can create a virtual disk from the OS-hidden RAM and am looking for suggestions how best to use the 740MB virtual disk to speed development in our environment. The slowest part of development for us is compiling as well as launching SpringSource dm Server. One option is to configure Vista to swap to the Ramdisk. That works, and noticeably speeds up development in low memory situations. However, the 3.3GB available to the OS is often sufficient and there are many situations where we do not use the swap file(s) much. Another option is to use the Ramdisk as a location for temporary files. Using the Vista mklink command, I created a hard link from where the SpringSource dm Server's work area normally resides to the Ramdisk. That significantly improves server startup times but does nothing for compile times. There are roughly 500MB still free on the Ramdisk when the work directory is fully utilized, so room for plenty more. What other files/directories might be candidates to place on the Ramdisk? Eclipse-related files? (Parts of) the JDK? Is there a free/open source tool for Vista that will show me which files are used most frequently during a period of time to reduce the guesswork?

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• proper use of volatile keyword

  - by luke

  I think i have a pretty good idea about the volatile keyword in java, but i'm thinking about re-factoring some code and i thought it would be a good idea to use it. i have a class that is basically working as a DB Cache. it holds a bunch of objects that it has read from a database, serves requests for those objects, and then occasionally refreshes the database (based on a timeout). Heres the skeleton public class Cache { private HashMap mappings =....; private long last_update_time; private void loadMappingsFromDB() { //.... } private void checkLoad() { if(System.currentTimeMillis() - last_update_time > TIMEOUT) loadMappingsFromDB(); } public Data get(ID id) { checkLoad(); //.. look it up } } So the concern is that loadMappingsFromDB could be a high latency operation and thats not acceptable, So initially i thought that i could spin up a thread on cache startup and then just have it sleep and then update the cache in the background. But then i would need to synchronize my class (or the map). and then i would just be trading an occasional big pause for making every cache access slower. Then i thought why not use volatile i could define the map reference as volatile private volatile HashMap mappings =....; and then in get (or anywhere else that uses the mappings variable) i would just make a local copy of the reference: public Data get(ID id) { HashMap local = mappings; //.. look it up using local } and then the background thread would just load into a temp table and then swap the references in the class HashMap tmp; //load tmp from DB mappings = tmp;//swap variables forcing write barrier Does this approach make sense? and is it actually thread-safe?

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• How to Post Javascript to a MySQL Database

  - by salientanimal

  Hi guys, I have created a form in HTLM and I m trying to post the information in the form to a MySQL database. My form make suse of a dynamic list selection that needs to be captured to the database. However when submtting the form I get the following error Error: Unknown column 'coulmn_name' in 'field list'. Here is my HTML CODE for the form <td height="94"><p align="justify">CALL TRACKER - ADMIN</p></td> Customer Name : E-Mail Address : </tr> <tr> <td width="29%" align="right" valign="middle"><strong>Case Number :</strong></td> <td> <input type="text" name="case_number" width="70%" align="left" valign="middle"> </td> </tr> <tr> <td width="29%" align="right" valign="middle"><strong>MSISDN :</strong></td> <td> <input type="text" name="msisdn" width="70%" align="left" valign="middle"> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Route Cause :</strong></td> <td width="71%" align="left" valign="middle"> <select name="route_cause" id="category" onChange="javascript: listboxchange1(this.options[this.selectedIndex].value);"> <!-- <select name="route_cause" id="route_cause"> --> <option value="">Select the Call Reason</option> <option value="Billing Admin">Billing Admin</option> <option value="Customer Care">Customer Care</option> <option value="Insurance">Insurance</option> <option value="Repairs">Repairs</option> <option value="SIM Swap">SIM Swap</option> <option value="UTI">UTI</option> </select> </td> </tr> <tr> <td align="right" valign="middle"> <strong>Call Type/Indexed To :</strong></td> <td align="left" valign="middle"> <script type="text/javascript" language="javascript" name="calltype_indexedto"> <!-- document.write('<select name="subcategory1" onChange="javascript: listboxchange2(this.options[this.selectedIndex].value);"><option value=""></option></select>') --> </script> </td> </tr> <tr> <td align="right" valign="middle"> <strong>Type/TAT :</strong></td> <td align="left" valign="middle"> <script type="text/javascript" language="javascript" name="type_tat"> <!-- document.write('<select name="subcategory2" onChange="javascript: listboxchange3(this.options[this.selectedIndex].value);"><option value=""></option></select>') --> </script> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Escalated To :</strong></td> <td width="71%" align="left" valign="middle"> <select name="escalatedto" id="escalated_to"> <option value="">Select the Escalation</option> <option value="Billing Ops">Billing Ops</option> <option value="Resolvers">Resolvers</option> <option value="Finance">Finance</option> <option value="Ressolver">Ressolver</option> <option value="Nudebt">Nudebt</option> <option value="Transunion">Transunion</option> <option value="N/A">N/A</option> </select> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Requested By :</strong></td> <td width="71%" align="left" valign="middle"> <select name="requestedby" id="requested_by"> <option value="">UTI Requested By</option> <option value="Billing">Billing</option> <option value="Customer Service">Customer Service</option> <option value="Insurance">Insurance</option> <option value="Management">Management</option> <option value="Repairs">Repairs</option> <option value="Retail Support">Retail Support</option> <option value="Retentions">Retentions</option> <option value="SIM Swap">SIM Swap</option> <option value="WOW">WOW</option> <option value="N/A">N/A</option> </select> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Province :</strong></td> <td width="71%" align="left" valign="middle"> <select name="province" id="province"> <option value="">Select the Province</option> <option value="Eastern Cape">Eastern Cape</option> <option value="Gauteng">Gauteng</option> <option value="Kwa-Zulu Natal">Kwa-Zulu Natal</option> <option value="Limpopo">Limpopo</option> <option value="Mpumalanga">Mpumalanga</option> <option value="North West">North West</option> <option value="Northern Cape">Northern Cape</option> <option value="Polokwane">Polokwane</option> <option value="Western Cape">Western Cape</option> <option value="Other">Other</option> </select> </td> </tr> <tr> <td width="29%" align="right" valign="middle"><strong>Comments :</strong></td> <td> <textarea rows ="5" cols="30" name="comments"> </textarea> </td> </tr> <tr> <td> <p> <input type="reset" value="Reset Form"><input type="Submit" value="Submit"> Here is my PHP CODE to write to the Database <?php $con = mysql_connect("hostname" ,"mysqusername" ,"mysqlpassword"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("databasename", $con); $sql="INSERT INTO customer_services_tracker (customer_name ,customer_email_address ,case_number ,msisdn ,route_cause ,calltype_indexedto ,type_tat ,escalatedto ,requestedby ,province ,comments ) VALUES ('$_POST[customer_name]' ,'$_POST[customer_email_address]' ,'$_POST[case_number]' ,'$_POST[msisdn]' ,'$_POST[route_cause]' ,'$_POST[calltype_indexedto]' ,'$_POST[type_tat]' ,'$_POST[escalatedto]' ,'$_POST[requestedby]' ,'$_POST[province]' ,'$_POST[comments]')"; $CatName = $rowCat["Name"]; if (!mysql_query($sql,$con)) { die('Error: ' . mysql_error()); } echo "1 record added"; mysql_close($con) ?>

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• C# 4.0 'dynamic' doesn't set ref/out arguments

  - by Buu Nguyen

  I'm experimenting with DynamicObject. One of the things I try to do is setting the values of ref/out arguments, as shown in the code below. However, I am not able to have the values of i and j in Main() set properly (even though they are set correctly in TryInvokeMember()). Does anyone know how to call a DynamicObject object with ref/out arguments and be able to retrieve the values set inside the method? class Program { static void Main(string[] args) { dynamic proxy = new Proxy(new Target()); int i = 10; int j = 20; proxy.Wrap(ref i, ref j); Console.WriteLine(i + ":" + j); // Print "10:20" while expect "20:10" } } class Proxy : DynamicObject { private readonly Target target; public Proxy(Target target) { this.target = target; } public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { int i = (int) args[0]; int j = (int) args[1]; target.Swap(ref i, ref j); args[0] = i; args[1] = j; result = null; return true; } } class Target { public void Swap(ref int i, ref int j) { int tmp = i; i = j; j = tmp; } }

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• Using shared_ptr to implement RCU (read-copy-update)?

  - by yongsun

  I'm very interested in the user-space RCU (read-copy-update), and trying to simulate one via tr1::shared_ptr, here is the code, while I'm really a newbie in concurrent programming, would some experts help me to review? The basic idea is, reader calls get_reading_copy() to gain the pointer of current protected data (let's say it's generation one, or G1). writer calls get_updating_copy() to gain a copy of the G1 (let's say it's G2), and only one writer is allowed to enter the critical section. After the updating is done, writer calls update() to do a swap, and make the m_data_ptr pointing to data G2. The ongoing readers and the writer now hold the shared_ptr of G1, and either a reader or a writer will eventually deallocate the G1 data. Any new readers would get the pointer to G2, and a new writer would get the copy of G2 (let's say G3). It's possible the G1 is not released yet, so multiple generations of data my co-exists. template <typename T> class rcu_protected { public: typedef T type; typedef std::tr1::shared_ptr<type> rcu_pointer; rcu_protected() : m_data_ptr (new type()) {} rcu_pointer get_reading_copy () { spin_until_eq (m_is_swapping, 0); return m_data_ptr; } rcu_pointer get_updating_copy () { spin_until_eq (m_is_swapping, 0); while (!CAS (m_is_writing, 0, 1)) {/* do sleep for back-off when exceeding maximum retry times */} rcu_pointer new_data_ptr(new type(*m_data_ptr)); // as spin_until_eq does not have memory barrier protection, // we need to place a read barrier to protect the loading of // new_data_ptr not to be re-ordered before its construction _ReadBarrier(); return new_data_ptr; } void update (rcu_pointer new_data_ptr) { while (!CAS (m_is_swapping, 0, 1)) {} m_data_ptr.swap (new_data_ptr); // as spin_until_eq does not have memory barrier protection, // we need to place a write barrier to protect the assignments of // m_is_writing/m_is_swapping be re-ordered bofore the swapping _WriteBarrier(); m_is_writing = 0; m_is_swapping = 0; } private: volatile long m_is_writing; volatile long m_is_swapping; rcu_pointer m_data_ptr; };

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• mmap only needed pages of kernel buffer to user space

  - by axeoth

  See also this answer: http://stackoverflow.com/a/10770582/1284631 I need something similar, but without having to allocate a buffer: the buffer is large, in theory, but the user space program only needs to access some parts of it (it mocks some registers of a hardware). As I cannot allocate with vmalloc_user() such a large buffer (kernel 32 bit, in embedded environment, no swap...), I followed the same approach as in the quoted answer, trying to allocate only those pages that are really requested by the user space. So: I use a my_mmap() function for the device file (actually, is the .mmap field of a struct uio_info) to set up the fields of the vma, then, in the vm_area_struct's .fault field (also named my_fault()), I should return a page. except that: In the my_fault() method of vm_area_struct, I cannot obtain a page through: vmf->page=vmalloc_to_page(my_buf + (vmf->pgoff << PAGE_SHIFT)); since there is no allocated buffer: my_buf = vmalloc_user(MY_BUF_SIZE); fails with "allocation failed: out of vmalloc space - use vmalloc= to increase size." (and there is no room or swap to increase that vmalloc= parameter). So, I would need to get a page from the kernel and fill the vmf->page field. How to allocate a page (I assume that the offset of the page is known, as it is vm->pgoff). What base memory should I use instead of my_buf? PS: I also did set up the vma->flags |= VM_NORESERVE; (in the my_mmap()), but not sure if it helps. Is there any vmalloc_user_unreserved()-like function? (let's say, lazy allocation) Also, writing 1 to /proc/sys/vm/overcommit_memory and large values (eg 500) to /proc/sys/vm/overcommit_ratio before trying to my_buf=vmalloc_user(<large_size>) didn't work.

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• Project Euler #14 and memoization in Clojure

  - by dbyrne

  As a neophyte clojurian, it was recommended to me that I go through the Project Euler problems as a way to learn the language. Its definitely a great way to improve your skills and gain confidence. I just finished up my answer to problem #14. It works fine, but to get it running efficiently I had to implement some memoization. I couldn't use the prepackaged memoize function because of the way my code was structured, and I think it was a good experience to roll my own anyways. My question is if there is a good way to encapsulate my cache within the function itself, or if I have to define an external cache like I have done. Also, any tips to make my code more idiomatic would be appreciated. (use 'clojure.test) (def mem (atom {})) (with-test (defn chain-length ([x] (chain-length x x 0)) ([start-val x c] (if-let [e (last(find @mem x))] (let [ret (+ c e)] (swap! mem assoc start-val ret) ret) (if (<= x 1) (let [ret (+ c 1)] (swap! mem assoc start-val ret) ret) (if (even? x) (recur start-val (/ x 2) (+ c 1)) (recur start-val (+ 1 (* x 3)) (+ c 1))))))) (is (= 10 (chain-length 13)))) (with-test (defn longest-chain ([] (longest-chain 2 0 0)) ([c max start-num] (if (>= c 1000000) start-num (let [l (chain-length c)] (if (> l max) (recur (+ 1 c) l c) (recur (+ 1 c) max start-num)))))) (is (= 837799 (longest-chain))))

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• How to partition bits in a bit array with less than linear time

  - by SiLent SoNG

  This is an interview question I faced recently. Given an array of 1 and 0, find a way to partition the bits in place so that 0's are grouped together, and 1's are grouped together. It does not matter whether 1's are ahead of 0's or 0's are ahead of 1's. An example input is 101010101, and output is either 111110000 or 000011111. Solve the problem in less than linear time. Make the problem simpler. The input is an integer array, with each element either 1 or 0. Output is the same integer array with integers partitioned well. To me, this is an easy question if it can be solved in O(N). My approach is to use two pointers, starting from both ends of the array. Increases and decreases each pointer; if it does not point to the correct integer, swap the two. int * start = array; int * end = array + length - 1; while (start < end) { // Assume 0 always at the end if (*end == 0) { --end; continue; } // Assume 1 always at the beginning if (*start == 1) { ++start; continue; } swap(*start, *end); } However, the interview insists there is a sub-linear solution. This makes me thinking hard but still not get an answer. Can anyone help on this interview question?

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• How to convert Big Endian and how to flip the highest bit?

  - by Robert Frank

  I am using a TStream to read binary data (thanks to this post: http://stackoverflow.com/questions/2878180/how-to-use-a-tfilestream-to-read-2d-matrices-into-dynamic-array). My next problem is that the data is Big Endian. From my reading, the Swap() method is seemingly deprecated. How would I swap the types below? 16-bit two's complement binary integer 32-bit two's complement binary integer 64-bit two's complement binary integer IEEE single precision floating-point - Are IEEE affected by Big Endian? And, finally, since the data is unsigned, the creators of this dataset have stored the unsigned values as signed integers (excluding the IEEE). They instruct that one need only add an offset (2^15, 2^31, and 2^63) to recover the unsigned data. But, they note that flipping the most significant bit is the fastest way to do that. How does one efficiently flip the most significant bit of a 16, 32, or 64-bit integer? So, if the data on disk (16-bit) is "85 FB" - the desired result after reading the data and swapping and bit flipping would be 1531. Is there a way to accomplish the swapping and bit flipping with generics so it fits into the generic answer at the link above? Yes, kids, THIS is how scientific astronomical data is stored by NASA, ESO, and all professional astronomers. This FITS standard is considered by some to be one of the most successful standards ever created in its proliferation and flexibility!

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• Sorting arrays in java

  - by user360706

  Write a static method in Java : public static void sortByFour (int[] arr) That receives as a paramater an array full of non-negative numbers (zero or positive) and sorts the array in the following way : In the beginning of the array all the numbers that devide by four without a remainder will appear. After them all the numbers in the array that devide by 4 with a remainder of 1 will appear. After them all the numbers in the array that devide by 4 with a remainder of 2 will appear. In the end of the array all the rest numbers (those who divide by 4 with the remainder 3) will appear. (The order of the numbers in each group doesn't matter) The method must be the most efficient it can. This is what I wrote but unfortunately it doesn't work well... :( public static void swap( int[] arr, int left, int right ) { int temp = arr[left]; arr[left] = arr[right]; arr[right] = temp; } public static void sortByFour( int[] arr ) { int left = 0; int right = ( arr.length - 1 ); int mid = ( arr.length / 2 ); while ( left < right ) { if ( ( arr[left] % 4 ) > ( arr[right] % 4 ) ) { swap( arr, left, right ); right--; } if ( ( arr[left] % 4 ) == ( arr[right] % 4 ) ) left++; else left++; } } Can someone please help me by fixing my code so that it will work well or rewriting it?

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