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  • optimize 2D array in C++

    - by Hristo
    I'm dealing with a 2D array with the following characteristics: const int cols = 500; const int rows = 100; int arr[rows][cols]; I access array arr in the following manner to do some work: for(int k = 0; k < T; ++k) { // for each trainee myscore[k] = 0; for(int i = 0; i < N; ++i) { // for each sample for(int j = 0; j < E[i]; ++j) { // for each expert myscore[k] += delta(i, anotherArray[k][i], arr[j][i]); } } } So I am worried about the array 'arr' and not the other one. I need to make this more cache-friendly and also boost the speed. I was thinking perhaps transposing the array but I wasn't sure how to do that. My implementation turns out to only work for square matrices. How would I make it work for non-square matrices? Also, would mapping the 2D array into a 1D array boost the performance? If so, how would I do that? Finally, any other advice on how else I can optimize this... I've run out of ideas, but I know that arr[j][i] is the place where I need to make changes because I'm accessing columns by columns instead of rows by rows so that is not cache friendly at all. Thanks, Hristo

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  • Nginx , Apache , Mysql , Memcache with server 4G ram. How optimize to enought memory?

    - by TomSawyer
    i have 1 dedicated server with Nginx proxy for Apache. Memcache, mysql, 4G Ram. These day, my visitor on my site wasn't increased, but my server get overload always in some specified time. (9AM - 15PM) Ram in use is increased second by second to full. that's moment, my server will get overload. i have to kill all apache , mysql service and reboot it to get free memory. that's the circle. here is my ram in use at the moment 160(nginx) 220(apache) 512(memcache) 924(mysql) here's process number 4(nginx) 14(apache) 5(memcache) 20(mysql) and here's my my.cnf config. someone can help me to optimize it? [mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql skip-locking skip-networking skip-name-resolve # enable log-slow-queries log-slow-queries = /var/log/mysql-slow-queries.log long_query_time=3 max_connections=200 wait_timeout=64 connect_timeout = 10 interactive_timeout = 25 thread_stack = 512K max_allowed_packet=16M table_cache=1500 read_buffer_size=4M join_buffer_size=4M sort_buffer_size=4M read_rnd_buffer_size = 4M max_heap_table_size=256M tmp_table_size=256M thread_cache=256 query_cache_type=1 query_cache_limit=4M query_cache_size=16M thread_concurrency=8 myisam_sort_buffer_size=128M # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 [mysqldump] quick max_allowed_packet=16M [mysql] no-auto-rehash [isamchk] key_buffer=256M sort_buffer=256M read_buffer=64M write_buffer=64M [myisamchk] key_buffer=256M sort_buffer=256M read_buffer=64M write_buffer=64M [mysqlhotcopy] interactive-timeout [mysql.server] user=mysql basedir=/var/lib [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid

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  • Google I/O 2010 - Optimize your site with Page Speed

    Google I/O 2010 - Optimize your site with Page Speed Google I/O 2010 - Optimize every bit of your site serving and web pages with Page Speed Tech Talks Richard Rabbat, Bryan McQuade Page Speed is an open-source Firefox/Firebug Add-on. Webmasters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them. Learn about the latest rules of web development we've added, updated optimizations, go over a new refreshed UI, see how to collect data through beacons to track progress over time, cut and paste fixes, and how to work with 3rd party libraries more effectively, including Google Analytics. For all I/O 2010 sessions, please go to code.google.com/events/io/2010/sessions.html From: GoogleDevelopers Views: 6 0 ratings Time: 47:15 More in Science & Technology

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  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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  • How to smartly optimize ads on website

    - by YardenST
    I've a content website that presents ads. Now, my team want to optimize it for a better experience for the users. (we really believe our ads are good for our users.) We are sure that every website deals with this issue and there must be some known ways and methods to deal with it, that smart people thought of before. so what i'm looking is a tested, working method to optimize ads. for example: if i was asking about optimizing my website in Google, I would expect you to answer me: learn SEO if i was asking about optimizing the use of my website: usability testing. navigation: information architecture what is the field that deals with optimizing ads?

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  • Top Strategies and Tips to Optimize My Site For Google

    Do you want to optimize your site for Google? Optimizing your site is a very good idea. There are certain tips which can help you to be successful in your venture. There are lots of people who think that it is quite tough to bring your website to the number one position in Google.

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  • Tips to Optimize Your Website

    Search engine optimization is a very essential task to be performed after designing a website. There are two major and powerful things that has to be done to optimize a website for various search engines.

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  • Tips to Optimize Your Website

    Search engine optimization is a very essential task to be performed after designing a website. There are two major and powerful things that has to be done to optimize a website for various search engines.

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  • MySQL Table does not support optimize

    - by Dscoduc
    My Wordpress tables appear to be in need of optimization so I looked into the commmand OPTIMIZE TABLE . When I run the command I get the following results: Table does not support optimize, doing recreate + analyze instead The tables are built using the Wordpress 2.91 installer and haven't been modified at all. Is this normal? How can I optimize my database to keep things working correctly?

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  • How can I optimize the import of this dataset in mysql?

    - by GeoffreyF67
    I've got the following table schema: CREATE TABLE `alexa` ( `id` int(10) unsigned NOT NULL, `rank` int(10) unsigned NOT NULL, `domain` varchar(63) NOT NULL, `domainStatus` varchar(6) DEFAULT NULL, PRIMARY KEY (`rank`), KEY `domain` (`domain`), KEY `id` (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 It takes several minutes to import the data. To me that seems rather slow as we're only talking about a million rows of data. What can I do to optimize the insert of this data? (already using disable keys) G-Man

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  • Optimize strategies for xml parsing?

    - by Future2020
    I am looking for general optimization tips and guidelines for xml parsing. One of the optimization strategies is of course selecting the "right" parser. A detailed comparison between the available parsers for ios can be found here http://www.raywenderlich.com/553/how-to-chose-the-best-xml-parser-for-your-iphone-project. However, I am currently trying to investigate general guidelines and tips on how to optimize by payloads to increase the performance as possible. This question is similar to (a question I have posted in the context of ios) but I have not got a sufficient answer. So this question is not in the context of any particular programming language.

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  • Learning to optimize with Assembly

    - by niktehpui
    I am a second year student of Computer Games Technology. I recently finished my first prototype of my "kind" of own pathfinder (that doesn't use A* instead a geometrical approach/pattern recognition, the pathfinder just needs the knowledge about the terrain that is in his view to make decisions, because I wanted an AI that could actually explore, if the terrain is already known, then it will walk the shortest way easily, because the pathfinder has a memory of nodes). Anyway my question is more general: How do I start optimizing algorithms/loops/for_each/etc. using Assembly, although general tips are welcome. I am specifically looking for good books, because it is really hard to find good books on this topic. There are some small articles out there like this one, but still isn't enough knowledge to optimize an algorithm/game... I hope there is a modern good book out there, that I just couldn't find...

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  • How to Easily Optimize & Manage Multiple Computers with Soluto

    - by Chris Hoffman
    Soluto is a quick, simple way to optimize and manage one or more computers – it really shines for managing multiple ones. If you’re already tech support for family or friends, Soluto can save you a lot of time. We’ve written about Soluto in the past, when it was in a closed beta. Anyone can now sign up for a free Soluto account and manage up to five computers from the same account. The HTG Guide to Hiding Your Data in a TrueCrypt Hidden Volume Make Your Own Windows 8 Start Button with Zero Memory Usage Reader Request: How To Repair Blurry Photos

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  • New Information Center - Optimize Performance of FMW 11g

    - by Daniel Mortimer
    Following on the heels of the recently published - "Reviewing Security for FMW 11g" Information Center, we are pleased to announce the publication of Information Center: Optimizing Performance of Oracle Fusion Middleware 11g [ID 1469617.2] Screenshot of ID 1469617.2 We are in the process of making further tweaks and changes to improve the other ** "Oracle Fusion Middleware 11g" Information Centers. So watch this space! ** You can navigate to these other Information Centers via the menu found on the left hand side of the "Optimize Performance" Information Center.

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  • Optimize SUMMARIZE with ADDCOLUMNS in Dax #ssas #tabular #dax #powerpivot

    - by Marco Russo (SQLBI)
    If you started using DAX as a query language, you might have encountered some performance issues by using SUMMARIZE. The problem is related to the calculation you put in the SUMMARIZE, by adding what are called extension columns, which compute their value within a filter context defined by the rows considered in the group that the SUMMARIZE uses to produce each row in the output. Most of the time, for simple table expressions used in the first parameter of SUMMARIZE, you can optimize performance by removing the extended columns from the SUMMARIZE and adding them by using an ADDCOLUMNS function. In practice, instead of writing SUMMARIZE( <table>, <group_by_column>, <column_name>, <expression> ) you can write: ADDCOLUMNS(     SUMMARIZE( <table>, <group by column> ),     <column_name>, CALCULATE( <expression> ) ) The performance difference might be huge (orders of magnitude) but this optimization might produce a different semantic and in these cases it should not be used. A longer discussion of this topic is included in my Best Practices Using SUMMARIZE and ADDCOLUMNS article on SQLBI, which also include several details about the DAX syntax with extended columns. For example, did you know that you can create an extended column in SUMMARIZE and ADDCOLUMNS with the same name of existing measures? It is *not* a good thing to do, and by reading the article you will discover why. Enjoy DAX!

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  • Optimize Many-to-Many with SUMMARIZE and Other Techniques

    - by Marco Russo (SQLBI)
    We are still in the early days of DAX and even if I have been using it since 2 years ago, there is still a lot to learn on that. One of the topics that historically interests me (and many of the readers here, probably) is the many-to-many relationships between dimensions in a dimensional data model. When I and Alberto wrote the The Many to Many Revolution 2.0 we discovered the SUMMARIZE based pattern very late in the whitepaper writing. It is very important for performance optimization and it should be always used. In the last month, Gerhard Brueckl also presented an approach based on cross table filtering behavior that simplify the syntax involved, even if it’s harder to explain how it works internally. I published a short article titled Optimize Many-to-Many Calculation in DAX with SUMMARIZE and Cross Table Filtering on SQLBI website just to provide a quick reference to the three patterns available. A further study is still required to compare performance between SUMMARIZE and Cross Table Filtering patterns. Up to now, I haven’t observed big differences between them, even if their execution plans might be not identical and this suggest me that depending on other conditions you might favor one over the other.

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  • Optimize Many-to-Many with SUMMARIZE and Other Techniques

    - by Marco Russo (SQLBI)
    We are still in the early days of DAX and even if I have been using it since 2 years ago, there is still a lot to learn on that. One of the topics that historically interests me (and many of the readers here, probably) is the many-to-many relationships between dimensions in a dimensional data model. When I and Alberto wrote the The Many to Many Revolution 2.0 we discovered the SUMMARIZE based pattern very late in the whitepaper writing. It is very important for performance optimization and it should be always used. In the last month, Gerhard Brueckl also presented an approach based on cross table filtering behavior that simplify the syntax involved, even if it’s harder to explain how it works internally. I published a short article titled Optimize Many-to-Many Calculation in DAX with SUMMARIZE and Cross Table Filtering on SQLBI website just to provide a quick reference to the three patterns available. A further study is still required to compare performance between SUMMARIZE and Cross Table Filtering patterns. Up to now, I haven’t observed big differences between them, even if their execution plans might be not identical and this suggest me that depending on other conditions you might favor one over the other.

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  • Transform Your Portal Experience and Optimize Online Engagement

    - by Christie Flanagan
    Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Does your portal environment foster collaboration between your business and your customers? Are you effectively managing your customer, employee, and partner relationships and engagement? Can your users access information through Web, mobile, and social channels? Online engagement solutions give organizations the ability to listen and respond to their customers, provide targeted experiences, and encourage interaction among customers and employees.Join us for a webcast on Thursday, April 12, 2012 at 10 a.m. PT / 1 p.m. ET, where Sachin Agarwal, Senior Director of Product Management and Kellsey Ruppel, Senior Product Marketing Manager for Oracle WebCenter, will tell you how to transform your portal experience and optimize online engagement. With Oracle WebCenter, you can: Deliver an optimized online experience for your users Create contextually relevant, targeted online experiences Provide intuitive and secure access to back-office applications Manage and moderate interactive, multichannel social interactions Register today and learn how to make your portals more interactive and engaging across multiple channels.

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  • How to optimize this JSON/JQuery/Javascript function in IE7/IE8?

    - by melaos
    hi guys, i'm using this function to parse this json data but i find the function to be really slow in IE7 and slightly slow in IE8. basically the first listbox generate the main product list, and upon selection of the main list, it will populate the second list. this is my data: [{"ProductCategoryId":209,"ProductCategoryName":"X-Fi","ProductSubCategoryId":668,"ProductSubCategoryName":"External Solutions","ProductId":15913,"ProductName":"Creative Xmod","ProductServiceLifeId":1},{"ProductCategoryId":209,"ProductCategoryName":"X-Fi","ProductSubCategoryId":668,"ProductSubCategoryName":"External Solutions","ProductId":15913,"ProductName":"Creative Xmod","ProductServiceLifeId":1},{"ProductCategoryId":209,"ProductCategoryName":"X-Fi","ProductSubCategoryId":668,"ProductSubCategoryName":"External Solutions","ProductId":18094,"ProductName":"Sound Blaster Wireless Receiver","ProductServiceLifeId":1},{"ProductCategoryId":209,"ProductCategoryName":"X-Fi","ProductSubCategoryId":668,"ProductSubCategoryName":"External Solutions","ProductId":16185,"ProductName":"Xdock Wireless","ProductServiceLifeId":1},{"ProductCategoryId":209,"ProductCategoryName":"X-Fi","ProductSubCategoryId":668,"ProductSubCategoryName":"External Solutions","ProductId":16186,"ProductName":"Xmod Wireless","ProductServiceLifeId":1}] and these are the functions that i'm using: //Three Product Panes function function populateMainPane() { $.getJSON('/Home/ThreePaneProductData/', function(data) { products = data; alert(JSON.stringify(products)); var prodCategory = {}; for (i = 0; i < products.length; i++) { prodCategory[products[i].ProductCategoryId] = products[i].ProductCategoryName; } //end for //take only unique product category to be used var id = 0; for (id in prodCategory) { if (prodCategory.hasOwnProperty(id)) { $(".LBox1").append("<option value='" + id + "'>" + prodCategory[id] + "</option>"); //alert(prodCategory[id]); } } var url = document.location.href; var parms = url.substring(url.indexOf("?") + 1).split("&"); for (var i = 0; i < parms.length; i++) { var parm = parms[i].split("="); if (parm[0].toLowerCase() == "pid") { $(".PanelProductReg").show(); var nProductIds = parm[1].split(","); for (var k = 0; k < nProductIds.length; k++) { var nProductId = parseInt(nProductIds[k], 10); for (var j = 0; j < products.length; j++) { if (nProductId == parseInt(products[j].ProductId, 10)) { addProductRow(nProductId, products[j].ProductName); j = products.length; } } //end for } } } }); } //end function function populateSubCategoryPane() { var subCategory = {}; for (var i = 0; i < products.length; i++) { if (products[i].ProductCategoryId == $('.LBox1').val()) subCategory[products[i].ProductSubCategoryId] = products[i].ProductSubCategoryName; } //end for //clear off the list box first $(".LBox2").html(""); var id = 0; for (id in subCategory) { if (subCategory.hasOwnProperty(id)) { $(".LBox2").append("<option value='" + id + "'>" + subCategory[id] + "</option>"); //alert(prodCategory[id]); } } } //end function is there anything i can do to optimize this or is this a known browser issue?

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