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  • Webserver optimization

    - by f-aminov
    Hi guys! I have a website hosted on a VPS (512Mb - minimum guranteed memory, 510Mhz proccessor, Debian 5.0 Lenny, Apache 2.2.9 with nginx 0.7.65 as a frontend to serve static content, MySQL 5.1.44, PHP 5.3.2 with APC caching). I'm a web developer, so I'm not very good at optimizing servers, but I've managed to install and setup all those neccessary components (LAMP, nginx, etc.). After that I decided to stress test my website (which uses Drupal 6.16 with caching and all possible optimization enabled) using a utility called "Webserver Stress Tool 7". And it seems to me that the results aren't any good - here is a graph (sorry, as a new user I'm not allowed to post images) As you can see the response time depending on amount of simultaneous users increases very quickly. With 10 simultaneous users the time is about 1000ms, with 100 simultaneous users it's about 15000ms (15s!). The question is do you think this is normal behavior for such a server or something is wrong with the settings and optimization? If you think something is wrong what particulary could be wrong? Any other suggestion how to speed this a little bit up?

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  • No optimization causes wrong search result

    - by KailZhang
    I just took over our solr/lucene stuff from my ex-colleague. But there is a weird bug. If there is no optimization after dataimport, actually if there are multiple segment files, the search result then will be wrong. We are using a customized solr searchComponent. As far as I know about lucene, optimization is only optimization which could improve the speed of indexing and should not affect search result. I doubt this may be related to multithreading or unclosed searcher/reader or something. Anybody can help? Thank you.

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  • How to cache dynamic javascript/jquery/ajax/json content with Akamai

    - by Starfs
    Trying to wrap my head around how things are cached on a CDN and it is new territory for me. In the document we received about sending in environment requests, it says "Dynamically-generated content will not benefit much from EdgeSuite". I feel like this is a simplified statement and there has to be a way to make it so you cache dynamically generated content if the tools are configured correctly. The site we are working with runs off a wordpress database, and uses javascript and ajax to build the pages, based on the json objects that php scripts have generated. The process - user's browser this URL, browser talks to edgesuite tools which will have cached certain pre-defined elements, and then requests from the host web server anything that is not cached, once edgesuite has compiled a combination of the two, it sends that information back to the browser. Can we not simply cache all json objects (and of course images, js, css) and therefore the web browser never has to hit the host server's database, at which point in essence, we have cached our dynamic content? Does anyone have any pointers on the most efficient configuration for this type of system -- Akamai/CDN -- to served javascript/ajax/json generated pages that ideally already hit pre-cached json data? Any and all feedback is welcome!

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  • SQL SERVER – Introduction to Rollup Clause

    - by pinaldave
    In this article we will go over basic understanding of Rollup clause in SQL Server. ROLLUP clause is used to do aggregate operation on multiple levels in hierarchy. Let us understand how it works by using an example. Consider a table with the following structure and data: CREATE TABLE tblPopulation ( Country VARCHAR(100), [State] VARCHAR(100), City VARCHAR(100), [Population (in Millions)] INT ) GO INSERT INTO tblPopulation VALUES('India', 'Delhi','East Delhi',9 [...]

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  • Python — Time complexity of built-in functions versus manually-built functions in finite fields

    - by stackuser
    Generally, I'm wondering about the advantages versus disadvantages of using the built-in arithmetic functions versus rolling your own in Python. Specifically, I'm taking in GF(2) finite field polynomials in string format, converting to base 2 values, performing arithmetic, then output back into polynomials as string format. So a small example of this is in multiplication: Rolling my own: def multiply(a,b): bitsa = reversed("{0:b}".format(a)) g = [(b<<i)*int(bit) for i,bit in enumerate(bitsa)] return reduce(lambda x,y: x+y,g) Versus the built-in: def multiply(a,b): # a,b are GF(2) polynomials in binary form .... return a*b #returns product of 2 polynomials in gf2 Currently, operations like multiplicative inverse (with for example 20 bit exponents) take a long time to run in my program as it's using all of Python's built-in mathematical operations like // floor division and % modulus, etc. as opposed to making my own division, remainder, etc. I'm wondering how much of a gain in efficiency and performance I can get by building these manually (as shown above). I realize the gains are dependent on how well the manual versions are built, that's not the question. I'd like to find out 'basically' how much advantage there is over the built-in's. So for instance, if multiplication (as in the example above) is well-suited for base 10 (decimal) arithmetic but has to jump through more hoops to change bases to binary and then even more hoops in operating (so it's lower efficiency), that's what I'm wondering. Like, I'm wondering if it's possible to bring the time down significantly by building them myself in ways that maybe some professionals here have already come across.

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  • Page Speed and it&rsquo;s affect on your business

    - by ihaynes
    Originally posted on: http://geekswithblogs.net/ihaynes/archive/2014/05/29/page-speed-and-itrsquos-affect-on-your-business.aspxPage speed was an important issue 10 years ago, when we all had slow modems, but became less so with the advent of fast broadband connections that even seemed to make Ajax unnecessary.  Then along came the mobile internet and we’re back to a world where page speed and asset optimisation are critical again. If you doubt this an article on SitePoint discussing ’Page Speed and Business Metrics’ may change your mind. http://www.sitepoint.com/page-speed-business-metrics/ Here are some of the figures it quotes: Walmart – saw a 2% increase in conversions for every second of improvement in page load time. Put another way, accumulated growth of revenues went up 1% for every 100 milliseconds of load time improvement. Yahoo – for every 400 milliseconds of improvement, the site traffic increased by 9%. The bottom line is that if people have to wait more than a few seconds for a page to fully render, particularly on a mobile device, they’ll probably go elsewhere. Ignore this at your peril.   For two previous posts on the subject see: Page Weight: 10 easy fixes Xat.com Image Optimiser – Useful for RWD/Mobile

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  • OpenGL's matrix stack vs Hand multiplying

    - by deft_code
    Which is more efficient using OpenGL's transformation stack or applying the transformations by hand. I've often heard that you should minimize the number of state transitions in your graphics pipeline. Pushing and popping translation matrices seem like a big change. However, I wonder if the graphics card might be able to more than make up for pipeline hiccup by using its parallel execution hardware to bulk multiply the vertices. My specific case. I have font rendered to a sprite sheet. The coordinates of each character or a string are calculated and added to a vertex buffer. Now I need to move that string. Would it be better to iterate through the vertex buffer and adjust each of the vertices by hand or temporarily push a new translation matrix?

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  • Minecraft Style Chunk building problem

    - by David Torrey
    I'm having some problems with speed in my chunk engine. I timed it out, and in its current state it takes a total ~5 seconds per chunk to fill each face's list. I have a check to see if each face of a block is visible and if it is not visible, it skips it and moves on. I'm using a dictionary (unordered map) because it makes sense memorywise to just not have an entry if there is no block. I've tracked my problem down to testing if there is an entry, and accessing an entry if it does exist. If I remove the tests to see if there is an entry in the dictionary for an adjacent block, or if the block type itself is seethrough, it runs within about 2-4 milliseconds. so here's my question: Is there a faster way to check for an entry in a dictionary than .ContainsKey()? As an aside, I tried TryGetValue() and it doesn't really help with the speed that much. If I remove the ContainsKey() and keep the test where it does the IsSeeThrough for each block, it halves the time, but it's still about 2-3 seconds. It only drops to 2-4ms if I remove BOTH checks. Here is my code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Runtime.InteropServices; using OpenTK; using OpenTK.Graphics.OpenGL; using System.Drawing; namespace Anabelle_Lee { public enum BlockEnum { air = 0, dirt = 1, } [StructLayout(LayoutKind.Sequential,Pack=1)] public struct Coordinates<T1> { public T1 x; public T1 y; public T1 z; public override string ToString() { return "(" + x + "," + y + "," + z + ") : " + typeof(T1); } } public struct Sides<T1> { public T1 left; public T1 right; public T1 top; public T1 bottom; public T1 front; public T1 back; } public class Block { public int blockType; public bool SeeThrough() { switch (blockType) { case 0: return true; } return false ; } public override string ToString() { return ((BlockEnum)(blockType)).ToString(); } } class Chunk { private Dictionary<Coordinates<byte>, Block> mChunkData; //stores the block data private Sides<List<Coordinates<byte>>> mVBOVertexBuffer; private Sides<int> mVBOHandle; //private bool mIsChanged; private const byte mCHUNKSIZE = 16; public Chunk() { } public void InitializeChunk() { //create VBO references #if DEBUG Console.WriteLine ("Initializing Chunk"); #endif mChunkData = new Dictionary<Coordinates<byte> , Block>(); //mIsChanged = true; GL.GenBuffers(1, out mVBOHandle.left); GL.GenBuffers(1, out mVBOHandle.right); GL.GenBuffers(1, out mVBOHandle.top); GL.GenBuffers(1, out mVBOHandle.bottom); GL.GenBuffers(1, out mVBOHandle.front); GL.GenBuffers(1, out mVBOHandle.back); //make new list of vertexes for each face mVBOVertexBuffer.top = new List<Coordinates<byte>>(); mVBOVertexBuffer.bottom = new List<Coordinates<byte>>(); mVBOVertexBuffer.left = new List<Coordinates<byte>>(); mVBOVertexBuffer.right = new List<Coordinates<byte>>(); mVBOVertexBuffer.front = new List<Coordinates<byte>>(); mVBOVertexBuffer.back = new List<Coordinates<byte>>(); #if DEBUG Console.WriteLine("Chunk Initialized"); #endif } public void GenerateChunk() { #if DEBUG Console.WriteLine("Generating Chunk"); #endif for (byte i = 0; i < mCHUNKSIZE; i++) { for (byte j = 0; j < mCHUNKSIZE; j++) { for (byte k = 0; k < mCHUNKSIZE; k++) { Random blockLoc = new Random(); Coordinates<byte> randChunk = new Coordinates<byte> { x = i, y = j, z = k }; mChunkData.Add(randChunk, new Block()); mChunkData[randChunk].blockType = blockLoc.Next(0, 1); } } } #if DEBUG Console.WriteLine("Chunk Generated"); #endif } public void DeleteChunk() { //delete VBO references #if DEBUG Console.WriteLine("Deleting Chunk"); #endif GL.DeleteBuffers(1, ref mVBOHandle.left); GL.DeleteBuffers(1, ref mVBOHandle.right); GL.DeleteBuffers(1, ref mVBOHandle.top); GL.DeleteBuffers(1, ref mVBOHandle.bottom); GL.DeleteBuffers(1, ref mVBOHandle.front); GL.DeleteBuffers(1, ref mVBOHandle.back); //clear all vertex buffers ClearPolyLists(); #if DEBUG Console.WriteLine("Chunk Deleted"); #endif } public void UpdateChunk() { #if DEBUG Console.WriteLine("Updating Chunk"); #endif ClearPolyLists(); //prepare buffers //for every entry in mChunkData map foreach(KeyValuePair<Coordinates<byte>,Block> feBlockData in mChunkData) { Coordinates<byte> checkBlock = new Coordinates<byte> { x = feBlockData.Key.x, y = feBlockData.Key.y, z = feBlockData.Key.z }; //check for polygonson the left side of the cube if (checkBlock.x > 0) { //check to see if there is a key for current x - 1. if not, add the vector if (!IsVisible(checkBlock.x - 1, checkBlock.y, checkBlock.z)) { //add polygon AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.left); } } else { //polygon is far left and should be added AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.left); } //check for polygons on the right side of the cube if (checkBlock.x < mCHUNKSIZE - 1) { if (!IsVisible(checkBlock.x + 1, checkBlock.y, checkBlock.z)) { //add poly AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.right); } } else { //poly for right add AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.right); } if (checkBlock.y > 0) { //check to see if there is a key for current x - 1. if not, add the vector if (!IsVisible(checkBlock.x, checkBlock.y - 1, checkBlock.z)) { //add polygon AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.bottom); } } else { //polygon is far left and should be added AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.bottom); } //check for polygons on the right side of the cube if (checkBlock.y < mCHUNKSIZE - 1) { if (!IsVisible(checkBlock.x, checkBlock.y + 1, checkBlock.z)) { //add poly AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.top); } } else { //poly for right add AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.top); } if (checkBlock.z > 0) { //check to see if there is a key for current x - 1. if not, add the vector if (!IsVisible(checkBlock.x, checkBlock.y, checkBlock.z - 1)) { //add polygon AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.back); } } else { //polygon is far left and should be added AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.back); } //check for polygons on the right side of the cube if (checkBlock.z < mCHUNKSIZE - 1) { if (!IsVisible(checkBlock.x, checkBlock.y, checkBlock.z + 1)) { //add poly AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.front); } } else { //poly for right add AddPoly(checkBlock.x, checkBlock.y, checkBlock.z, mVBOHandle.front); } } BuildBuffers(); #if DEBUG Console.WriteLine("Chunk Updated"); #endif } public void RenderChunk() { } public void LoadChunk() { #if DEBUG Console.WriteLine("Loading Chunk"); #endif #if DEBUG Console.WriteLine("Chunk Deleted"); #endif } public void SaveChunk() { #if DEBUG Console.WriteLine("Saving Chunk"); #endif #if DEBUG Console.WriteLine("Chunk Saved"); #endif } private bool IsVisible(int pX,int pY,int pZ) { Block testBlock; Coordinates<byte> checkBlock = new Coordinates<byte> { x = Convert.ToByte(pX), y = Convert.ToByte(pY), z = Convert.ToByte(pZ) }; if (mChunkData.TryGetValue(checkBlock,out testBlock )) //if data exists { if (testBlock.SeeThrough() == true) //if existing data is not seethrough { return true; } } return true; } private void AddPoly(byte pX, byte pY, byte pZ, int BufferSide) { //create temp array GL.BindBuffer(BufferTarget.ArrayBuffer, BufferSide); if (BufferSide == mVBOHandle.front) { //front face mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.front.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ + 1) }); } else if (BufferSide == mVBOHandle.right) { //back face mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.back.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); } else if (BufferSide == mVBOHandle.top) { //left face mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.left.Add(new Coordinates<byte> { x = (byte)(pX), y = (byte)(pY + 1), z = (byte)(pZ) }); } else if (BufferSide == mVBOHandle.bottom) { //right face mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ + 1) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY) , z = (byte)(pZ) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.right.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); } else if (BufferSide == mVBOHandle.front) { //top face mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ + 1) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY + 1), z = (byte)(pZ) }); mVBOVertexBuffer.top.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY + 1), z = (byte)(pZ) }); } else if (BufferSide == mVBOHandle.back) { //bottom face mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY), z = (byte)(pZ + 1) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY), z = (byte)(pZ) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY), z = (byte)(pZ) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY), z = (byte)(pZ) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX + 1), y = (byte)(pY), z = (byte)(pZ + 1) }); mVBOVertexBuffer.bottom.Add(new Coordinates<byte> { x = (byte)(pX) , y = (byte)(pY), z = (byte)(pZ + 1) }); } } private void BuildBuffers() { #if DEBUG Console.WriteLine("Building Chunk Buffers"); #endif GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.front); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.front.Count), mVBOVertexBuffer.front.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.back); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.back.Count), mVBOVertexBuffer.back.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.left); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.left.Count), mVBOVertexBuffer.left.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.right); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.right.Count), mVBOVertexBuffer.right.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.top); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.top.Count), mVBOVertexBuffer.top.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer, mVBOHandle.bottom); GL.BufferData(BufferTarget.ArrayBuffer, (IntPtr)(Marshal.SizeOf(new Coordinates<byte>()) * mVBOVertexBuffer.bottom.Count), mVBOVertexBuffer.bottom.ToArray(), BufferUsageHint.StaticDraw); GL.BindBuffer(BufferTarget.ArrayBuffer,0); #if DEBUG Console.WriteLine("Chunk Buffers Built"); #endif } private void ClearPolyLists() { #if DEBUG Console.WriteLine("Clearing Polygon Lists"); #endif mVBOVertexBuffer.top.Clear(); mVBOVertexBuffer.bottom.Clear(); mVBOVertexBuffer.left.Clear(); mVBOVertexBuffer.right.Clear(); mVBOVertexBuffer.front.Clear(); mVBOVertexBuffer.back.Clear(); #if DEBUG Console.WriteLine("Polygon Lists Cleared"); #endif } }//END CLASS }//END NAMESPACE

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  • How often is software speed evident in the eyes of customers?

    - by rwong
    In theory, customers should be able to feel the software performance improvements from first-hand experience. In practice, sometimes the improvements are not noticible enough, such that in order to monetize from the improvements, it is necessary to use quotable performance figures in marketing in order to attract customers. We already know the difference between perceived performance (GUI latency, etc) and server-side performance (machines, networks, infrastructure, etc). How often is it that programmers need to go the extra length to "write up" performance analyses for which the audience is not fellow programmers, but managers and customers?

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  • CPU Architecture and floating-point math

    - by Jo-Herman Haugholt
    I'm trying to wrap my head around some details about how floating point math is performed on the CPU, trying to better understand what data types to use etc. I think I have a fairly good understanding of how integer math is performed. If I've understood correctly, and disregarding SIMD, a 32-bit CPU will generally perform integer math at at least 32-bit precision etc. Is it correct that floating-point math is dependent on the presence of a FPU? And that the FPU on the x86 is 80-bit, so floating point math is performed at this precision unless using SIMD? What about ARM?

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  • "Optimal" game loop for 2D side-scroller

    - by MrDatabase
    Is it possible to describe an "optimal" (in terms of performance) layout for a 2D side-scroller's game loop? In this context the "game loop" takes user input, updates the states of game objects and draws the game objects. For example having a GameObject base class with a deep inheritance hierarchy could be good for maintenance... you can do something like the following: foreach(GameObject g in gameObjects) g.update(); However I think this approach can create performance issues. On the other hand all game objects' data and functions could be global. Which would be a maintenance headache but might be closer to an optimally performing game loop. Any thoughts? I'm interested in practical applications of near optimal game loop structure... even if I get a maintenance headache in exchange for great performance.

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  • OpenGL Performance Questions

    - by Daniel
    This subject, as with any optimisation problem, gets hit on a lot, but I just couldn't find what I (think) I want. A lot of tutorials, and even SO questions have similar tips; generally covering: Use GL face culling (the OpenGL function, not the scene logic) Only send 1 matrix to the GPU (projectionModelView combination), therefore decreasing the MVP calculations from per vertex to once per model (as it should be). Use interleaved Vertices Minimize as many GL calls as possible, batch where appropriate And possibly a few/many others. I am (for curiosity reasons) rendering 28 million triangles in my application using several vertex buffers. I have tried all the above techniques (to the best of my knowledge), and received almost no performance change. Whilst I am receiving around 40FPS in my implementation, which is by no means problematic, I am still curious as to where these optimisation 'tips' actually come into use? My CPU is idling around 20-50% during rendering, therefore I assume I am GPU bound for increasing performance. Note: I am looking into gDEBugger at the moment Cross posted at StackOverflow

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  • How to go about unused CSS issues

    - by Saif Bechan
    I am running some speedtests on a blog, and I always get complaints about unused CSS. But this is not CSS that I never use, it is just not used on that particular page. Now I work in a structured way, but there still has to be some CSS in the file that will not be used, because you need it on another page. I do not think that using different CSS files on different pages is the way to go, I think you are much better off just creating one big file that can be cached. Now is there an elegant way of dealing with this, or do you just stick with it.

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  • Open source vs commercial game engines

    - by Vanangamudi
    How commercial game accomplsih stunnning graphics with smooth game play? I am a huge die hard fan and follower of GNU Stallman and his philosophies and other Libre people Cmon how wud I miss Linus. but I got to admit commercial games does excellent jobs. One such good example is Assasin's Creed from Ubisoft. It has good quality graphcis and plays smoothly in my Dual core CPU with Nvidia Geforce 8400ES. Rockstar GTA4 has awesome graphcis but it's slower than AC considering the graphics quality tradeoff. Age of Empires from Ensemble studios, does include Massive crowd AI simulation, yet it plays so smoothly with eyecandy graphics and very large weapon sets and different techtree elements on the other hand. Open source games like Glest, 0A.D(still in alpha :) are not so smooth even though they have very restricted abilities? Coming to question: how do game companies achieve such optmizations, or the open source community is not doing optimizations, or there are any propriarity technological elements that benefits only the companies exists huh?? e.g the OpenSubDiv from Pixar just released open to community?? something like that. and why it is hard to implement optimizations? are there any legal restrictions???

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  • Can AJAX in a CMS slow down your server

    - by Saif Bechan
    I am currently developing some plugins for WordPress, and I was wondering which route to take. Let's take an example, you want to display the last 3 tweets on your page. Option 1 You do things the normal way inside WordPress. Someone enters the website, while generating the page, you fetch the tweets in php via the twitter api, and just display them where you want. Now the small problem with this is, that you have to wait for the response from twitter. This takes a few ms. NO real problem, but this is question is just out of curiosity. Option 2 Here you don't do anything in WordPress on the initial load, but you do have the API inside. Now you just generate the page, and as soon as the page is done on the client side, you do a small AJAX call back to the server via a WordPress plugin, to fetch your latest tweets. Also called asynchronously. Now the problem with this IMO is that you have much more stress on your server. For starters you have two HTTP requests instead of one. Secondly the WordPress core has to load two times instead of one. Other options Now I know there are a lot of other options: 1) Getting the tweets directly via javascript, no stress on the server at all. 2) Cache the tweets so they are fetched from the DB instead of using the API every time. 3) Getting the tweets from an ajax call that is not a WordPress plugin. 4) Many more. My Question Now my question is if you only compare 1 and 2, which would be a better choice.

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  • How to improve performance of map that loads new overlay images

    - by anthonysomerset
    I have inherited a website to maintain that uses a html map overlaying a real map to link specific countries to specific pages. previously it loaded the default map image, then with some javascript it would change the image src to an image with that particular country in a different colour on mouseover and reset the image source back to the original image on mouse out to make maintenance (adding new countries) easier i made the initial map a background image by utilising some CSS for the div tag, and then created new images for each country which only had that countries hightlight so that the images remain fairly small. this works great but theres one issue which is particularly noticeable on slower internet connections when you hover over a country if you dont have the image file in your browser cache or downloaded it wont load the image unless you hover over another country and then back onto the first country - i guess this is due to the image having to manually be downloaded on first hover. My question: is it possible to force the load of these extra images AFTER the page and all the other assets have finished loading so that this behaviour is all but eliminated? the html code for the MAP is as follows: <div class="gtmap"><img id="Image-Maps_6200909211657061" src="<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png" usemap="#Image-Maps_6200909211657061" alt="We offer Guided Motorcycle Tours all around the world" width="615" height="296" /> <map id="_Image-Maps_6200909211657061" name="Image-Maps_6200909211657061"> <area shape="poly" coords="511,134,532,107,542,113,520,141" href="/guided-motorcycle-tours-japan/" alt="Guided Japan Motorcycle Tours" title="Japan" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-japan.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="252,61,266,58,275,64,262,68" href="/guided-motorcycle-tour.php?iceland-motorcycle-adventure-39" alt="Guided Iceland Motorcycle Tours" title="Iceland" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-iceland.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="587,246,597,256,577,279,568,270" href="/guided-motorcycle-tour.php?new-zealand-south-island-adventure-10" alt="New Zealand Guided Motorcycle Tours" title="New Zealand" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-nz.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="418,133,412,145,412,154,421,178,430,180,430,166,443,154,443,145,438,144,433,142,430,138,431,130,430,129,425,128" href="/guided-motorcycle-tours-india/" alt="India Guided Motorcycle Tours" title="India" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-india.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="460,152,466,149,474,165,470,171,466,161" href="/guided-motorcycle-tours-laos/" alt="Laos Guided Motorcycle Tours" title="Laos" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-laos.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="468,179,475,166,468,152,475,152,482,169" href="/guided-motorcycle-tour.php?indochina-motorcycle-adventure-tour-32" onClick="javascript: pageTracker._trackPageview('/internal-links/guided-tours/map/vietnam');" alt="Vietnam Guided Motorcycle Tours" title="Vietnam" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-viet.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="330,239,337,235,347,226,352,233,351,243,344,250,335,253,327,255,323,249,322,242,323,241" href="/guided-motorcycle-tours-southafrica/" alt="South Africa Guided Motorcycle Tours" title="South Africa" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-sa.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="290,77,293,86,298,96,286,102,285,97,285,89,282,84,282,79" href="/guided-motorcycle-tour.php?great-britain-isle-of-man-scotland-wales-uk-18" alt="United Kingdom" title="United Kingdom Guided Motorcycle Tours" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-uk.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="357,118,368,118,369,126,345,129,338,125,338,117,342,115,348,116" href="/guided-motorcycle-tour.php?explore-turkey-adventure-45" alt="Turkey" title="Turkey Guided Motorcycle Tours" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-turkey.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="206,95,193,101,185,101,178,106,165,111,157,109,147,105,134,103,121,103,107,103,96,103,86,104,81,99,77,91,70,83,62,79,60,72,61,64,59,57,60,51,71,50,83,49,95,50,107,54,117,53,129,47,137,36,148,37,163,38,177,44,187,54,195,60,184,72,191,80,200,87" href="/guided-motorcycle-tours-canada/" alt="Guided Canada Motorcycle Tours" title="Canada" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-canada.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="61,75,60,62,60,55,59,44,51,44,43,43,36,42,28,43,23,48,17,51,15,62,19,74,27,79,19,83,16,93,35,83,43,77,50,75,55,75" href="/guided-motorcycle-tours-alaska/" alt="Guided Alaska Motorcycle Tours" title="Alaska" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-alaska.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="82,101,99,101,133,101,148,105,161,110,172,106,187,100,180,113,171,122,165,131,159,149,147,141,137,140,129,147,120,141,112,138,103,137,93,132,86,122,86,112,86,106" href="/guided-motorcycle-tours-usa/" alt="USA Guided Motorcycle Tours" title="USA" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-usa.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="178,225,180,214,175,208,174,204,178,198,174,193,167,192,157,199,158,204,164,211,167,218" href="/guided-motorcycle-tour.php?peru-machu-picchu-adventure-25" alt="Peru Guided Motorcycle Tours" title="Peru" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-peru.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="172,226,169,239,166,256,166,267,164,279,171,277,174,262,175,250,179,234,180,225,176,224" href="/guided-motorcycle-tours-chile/" alt="Guided Chile Motorcycle Tours" title="Chile" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-chile.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> <area shape="poly" coords="199,260,194,261,187,265,184,276,183,296,170,292,168,282,174,270,174,257,177,245,180,230,190,228,205,237,199,245" href="/guided-motorcycle-tours-argentina/" alt="Guided Argentina Motorcycle Tours" title="Argentina" onmouseover="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-arg.png';" onmouseout="if(document.images) document.getElementById('Image-Maps_6200909211657061').src='<?php echo cdnhttpsCheck(); ?>assets/wmap/a-guided-tours-map-blank.png';" /> </map> </div> The <?php echo cdnhttpsCheck(); ?> is just a site specific function that gets the correct web domain/url from a config file to load resources from CDN where possible (eg all non HTTPS requests) We are loading Jquery at the bottom of the HTML if anybody wonders why it is missing from the code snippet for reference, the page with the map in question is found here: http://www.motoquest.com/guided-motorcycle-tours/

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  • Designing a Database Application with OOP

    - by Tim C
    I often develop SQL database applications using Linq, and my methodology is to build model classes to represent each table, and each table that needs inserting or updating gets a Save() method (which either does an InsertOnSubmit() or SubmitChanges(), depending on the state of the object). Often, when I need to represent a collection of records, I'll create a class that inherits from a List-like object of the atomic class. ex. public class CustomerCollection : CoreCollection<Customer> { } Recently, I was working on an application where end-users were experiencing slowness, where each of the objects needed to be saved to the database if they met a certain criteria. My Save() method was slow, presumably because I was making all kinds of round-trips to the server, and calling DataContext.SubmitChanges() after each atomic save. So, the code might have looked something like this foreach(Customer c in customerCollection) { if(c.ShouldSave()) { c.Save(); } } I worked through multiple strategies to optimize, but ultimately settled on passing a big string of data to a SQL stored procedure, where the string has all the data that represents the records I was working with - it might look something like this: CustomerID:34567;CurrentAddress:23 3rd St;CustomerID:23456;CurrentAddress:123 4th St So, SQL server parses the string, performs the logic to determine appropriateness of save, and then Inserts, Updates, or Ignores. With C#/Linq doing this work, it saved 5-10 records / s. When SQL does it, I get 100 records / s, so there is no denying the Stored Proc is more efficient; however, I hate the solution because it doesn't seem nearly as clean or safe. My real concern is that I don't have any better solutions that hold a candle to the performance of the stored proc solution. Am I doing something obviously wrong in how I'm thinking about designing database applications? Are there better ways of designing database applications?

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  • Optimizing MySQL -

    - by Josh
    I've been researching how to optimize MySQL a bit, but I still have a few questions. MySQL Primer Results http://pastie.org/private/lzjukl8wacxfjbjhge6vw Based on this, the first problem seems to be that the max_connections limit is too low. I had a similar problem with Apache initially, the max connection limit was set to 100, and the web server would frequently lock up and take an excruciatingly long time to deliver pages. Raising the connection limit to 512 fixed this issue, and I read that raising the connection limit on MySQL to match this was considered good practice. Being that MySQL has actually been "locking up" recently as well (connections have been refused entirely for a few minutes at a time at random intervals) I'm assuming this is the main cause of the issue. However, as far as table cache goes, I'm not sure what I should set this as. I've read that setting this too high can hinder performance further, so should I raise this to right around 551, 560, 600, or do something else? Lastly, as far as raising the join_buffer_size value goes, this doesn't even seem to be included in Debian's my.cnf file by default. Assuming there's not much I can do about adding indexes, should I look into raising this? Any suggested values? Any suggestions in general here would be appreciated as well. Edit: Here's the number of open tables the MySQL server is reporting. I believe this value is related to my question (Opened_tables: 22574)

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