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• Can GPU capabilities impact virtual machine performance?

  - by Dave White

  While this many not seem like a programming question directly, it impacts my development activities and so it seems like it belongs here. It seems that more and more developers are turning to virtual environments for development activities on their computers, SharePoint development being a prime example. Also, as a trainer, I have virtual training environments for all of the classes that I teach. I recently purchased a new Dell E6510 to travel around with. It has the i7 620M (Dual core, HyperThreaded cpu running at 2.66GHz) and 8 GB of memory. Reading the spec sheet, it sounded like it would be a great laptop to carry around and run virtual machines on. Getting the laptop though, I've been pretty disappointed with the user experience of developing in a virtual machine. Giving the Virtual Machine 4 GB of memory, it was slow and I could type complete sentences and watch the VM "catchup". My company has training laptops that we provide for our classes. They are Dell Precision M6400 Intel Core 2 Duo P8700 running at 2.54Ghz with 8 GB of memory and the experience on this laptops is night and day compared to the E6510. They are crisp and you barely aware that you are running in a virtual environment. Since the E6510 should be faster in all categories than the M6400, I couldn't understand why the new laptop was slower, so I did a component by component comparison and the only place where the E6510 is less performant than the M6400 is the graphics department. The M6400 is running a nVidia FX 2700m GPU and the E6510 is running a nVidia 3100M GPU. Looking at benchmarks of the two GPUs suggest that the FX 2700M is twice as fast as the 3100M. http://www.notebookcheck.net/Mobile-Graphics-Cards-Benchmark-List.844.0.html 3100M = 111th (E6510) FX 2700m = 47th (Precision M6400) Radeon HD 5870 = 8th (Alienware) The host OS is Windows 7 64bit as is the guest OS, running in Virtual Box 3.1.8 with Guest Additions installed on the guest. The IDE being used in the virtual environment is VS 2010 Premium. So after that long setup, my question is: Is the GPU significantly impacting the virtual machine's performance or are there other factors that I'm not looking at that I can use to boost the vm's performance? Do we now have to consider GPU performance when purchasing laptops where we expect to use virtualized development environments? Thanks in advance. Cheers, Dave

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• Fastest way to compute a "Visual" checksum of an image

  - by ensnare

  I'm looking to create an ID system for cataloging images. I can't use md5() since that will change if I alter the EXIF tags of the image. I am currently using the SHA1 checksum computed by imagemagick. It works perfectly, but it's really, really slow on larger images (~15 seconds on a quad-core xeon for a 21 megapixel JPG). Are there any other "visual" methods of uniquely identifying an image that would be faster? Thank you.

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• SQLite bulk insert on iPhone not working

  - by App_beginner

  Hi. I have been struggling with this seeminly easy problem for 48 hours, and I am no closer to a solution. So I was hoping that someone might be able to help me. I am building a app, that use a combination of a local (SQLite) database and an online database (PHP/MYSQL). The app is nearly finished. Checked for leaks and work like a charm. However the very last part is the part I have struggled with. On launch, I want the app to check for changes to the online databse, and if there is. I want it to download and parse a xml file containing the changes. Everything is working fine this far. But when I try to bulk insert my parsed data to my database, the app crashes, giving a NSInternalInconsistency error. Due to the database returning SQLITE_MISUSE. I have done a lot of googling, but am still unable to solve my problem. So I am putting the code here, hoping that someone can help me fix this. And I know that I should have used core data for this. But this is the very last part I am struggling with, and I am very reluctant to changing my entire code now. Core data will have to come in the update. Here is the error I recieve: Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Error while inserting data. 'library routine called out of sequence'' Here is my code: -(void)UpdateDatabase:(const char *)_query NewValues:(NSMutableArray *)_odb dbn:(NSString *)_dbn dbp:(NSString *)_dbp { sqlite3 *database; NSMutableArray *NewValues = _odb; int i; const char *query = _query; sqlite3_stmt *addStmt; for (i = 1; i < [NewValues count]; i++) { if(sqlite3_prepare_v2(database, query, -1, &addStmt, NULL) == SQLITE_OK) { sqlite3_bind_text(addStmt, 1, [[[NewValues objectAtIndex:i] name] UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_text(addStmt, 2, [[[NewValues objectAtIndex:i] city]UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_double(addStmt, 3, [[[NewValues objectAtIndex:i] lat] doubleValue]); sqlite3_bind_int(addStmt, 4, [[[NewValues objectAtIndex:i] long] doubleValue]); sqlite3_bind_int(addStmt, 5, [[[NewValues objectAtIndex:i] code] intValue]); } if(SQLITE_DONE != sqlite3_step(addStmt)) { NSAssert1(0, @"Error while inserting data. '%s'", sqlite3_errmsg(database)); } //Reset the add statement. sqlite3_reset(addStmt); } }

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• Adding a Shadow to a NSImageView

  - by Kevin Sylvestre

  Sorry for the seemingly simple question. I have a NSImageView (added in interface builder) and want to add a shadow outline. I tried using the 'Image View Effects' section of the 'Inspector' but this required enabling a core animation layer. If I set it for the 'Content View' I have very strange appearance side effects. If I set it for the 'Image View' the shadow is cropped (sorry, can't resize the image view). Any ideas?

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• Please help with iPhone Memory & Images, memory usage crashing app

  - by Andrew Gray

  I have an issue with memory usage relating to images and I've searched the docs and watched the videos from cs193p and the iphone dev site on memory mgmt and performance. I've searched online and posted on forums, but I still can't figure it out. The app uses core data and simply lets the user associate text with a picture and stores the list of items in a table view that lets you add and delete items. Clicking on a row shows the image and related text. that's it. Everything runs fine on the simulator and on the device as well. I ran the analyzer and it looked good, so i then starting looking at performance. I ran leaks and everything looked good. My issue is when running Object Allocations as every time i select a row and the view with the image is shown, the live bytes jumps up a few MB and never goes down and my app eventually crashes due to memory usage. Sorting the live bytes column, i see 2 2.72MB mallocs (5.45Mb total), 14 CFDatas (3.58MB total), 1 2.74MB malloc and everything else is real small. the problem is all the related info in instruments is really technical and all the problem solving examples i've seen are just missing a release and nothing complicated. Instruments shows Core Data as the responsible library for all but one (libsqlite3.dylib the other) with [NSSQLCore _prepareResultsFromResultSet:usingFetchPlan:withMatchingRows:] as the caller for all but one (fetchResultSetReallocCurrentRow the other) and im just not sure how to track down what the problem is. i've looked at the stack traces and opened the last instance of my code and found 2 culprits (below). I havent been able to get any responses at all on this, so if anyone has any tips or pointers, I'd really appreciate it!!!! //this is from view controller that shows the title and image - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; self.title = item.title; self.itemTitleTextField.text = item.title; if ([item.notes length] == 0) { self.itemNotesTextView.hidden = YES; } else { self.itemNotesTextView.text = item.notes; } //this is the line instruments points to UIImage *image = item.photo.image; itemPhoto.image = image; } - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { // Delete the managed object for the given index path NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; [context deleteObject:[fetchedResultsController objectAtIndexPath:indexPath]]; // Save the context. NSError *error = nil; if (![context save:&error]) //this is the line instruments points to { NSLog(@"Unresolved error %@, %@", error, [error userInfo]); exit(-1); } } }

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• How to translate,use JSON in GWT?

  - by graybow

  I'm new in gwt. and need to know how to use JSON in gwt so i try this simple data loader but i'm still confuse. I create a project named 'tesdb3' in eclipse. I create the PHP side to access the database, and made the output as JSON.. I create the userdata.php in folder war. then I compile tesdb3 project. Folder tesdb3 and the userdata.php in war moved in local server(I use WAMP). I put the PHP in folder tesdb3. This is the result from my localhost/phpmyadmin/tesdb3/userdata.php [{"kode":"002","nama":"bambang gentolet"}{"kode":"012","nama":"Algiz"}] From that result I think the PHP side was working good.Then I create UserData.java as JSNI overlay like this: package com.tesdb3.client; import com.google.gwt.core.client.JavaScriptObject; class UserData extends JavaScriptObject{ protected UserData() {} public final native String getKode() /*-{ return this.kode; }-*/; public final native String getNama() /*-{ return this.nama; }-*/; public final String getFullData() { return getKode() + ":" + getNama(); } } Then Finally in the tesdb3.java: public class Tesdb3 implements EntryPoint { String url= "http://localhost/phpmyadmin/tesdb3/datauser.php"; private native JsArray<UserData> getuserdata(String Json) /*-{ return eval(json); }-*/; public void LoadData() throws RequestException{ RequestBuilder builder = new RequestBuilder(RequestBuilder.POST, URL.encode(url)); builder.sendRequest(null, new RequestCallback(){ @Override public void onError(Request request, Throwable exception) { Window.alert("error " + exception); } public void onResponseReceived(Request request, Response response) { getuserdata(response.getText()); //this is how i use the userdata json(is this already translated?) UserData UD = null; String LKode =UD.getKode(); String LName =UD.getNama(); Label L = new Label(LKode+""+LName); RootPanel.get().add(L); } }); } public void onModuleLoad() { try { LoadData(); } catch (RequestException e) { e.printStackTrace(); } } } The result is blank(i use development mode). and there was an eror like this:(I show it just some part) 10:46:29.984 [ERROR] [tesdb3] Uncaught exception escaped com.google.gwt.core.client.JavaScriptException: (ReferenceError): json is not defined fileName: http://localhost:1092 lineNumber: 2 stack: ("")@http://localhost:1092:2 My question is: How I use the translated Json in right way?? Is there any wrong use from my code? Is that necessary to move the compiled project to local server folder?(i do it following a tutorial from google). Sorry too many ask. but i'm really really confused.

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• PHP custom class and function autocompletion in TextMate project

  - by Koen.

  Is there a bundle which completes my custom classes and functions in a TextMate project? Like the code hints with PHP core functions?

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• many-to-many performance concerns with fluent nhibernate.

  - by Ciel

  I have a situation where I have several many-to-many associations. In the upwards of 12 to 15. Reading around I've seen that it's generally believed that many-to-many associations are not 'typical', yet they are the only way I have been able to create the associations appropriate for my case, so I'm not sure how to optimize any further. Here is my basic scenario. class Page { IList<Tag> Tags { get; set; } IList<Modification> Modifications { get; set; } IList<Aspect> Aspects { get; set; } } This is one of my 'core' classes, and coincidentally one of my core tables. Virtually half of the objects in my code can have an IList<Page>, and some of them have IList<T> where T has its own IList<Page>. As you can see, from an object oriented standpoint, this is not really a problem. But from a database standpoint this begins to introduce a lot of junction tables. So far it has worked fine for me, but I am wondering if anyone has any ideas on how I could improve on this structure. I've spent a long time thinking and in order to achieve the appropriate level of association required, I cannot think of any way to improve it. The only thing I have come up with is to make intermediate classes for each object that has an IList<Page>, but that doesn't really do anything that the HasManyToMany does not already do except introduce another class. It does not extend the functionality and, from what I can tell, it does not improve performance. Any thoughts? I am also concerned about Primary Key limits in this scenario. Most everything needs to be able to have these properties, but the Pages cannot be unique to each object, because they are going to be frequently shared and joined between multiple objects. All relationships are one-sided. (That is, a Page has no knowledge of what owns it). Because of this, I also have no Inverse() mapped HasManyToMany collections. Also, I have read the similar question : Usage of ORMs like NHibernate when there are many associations - performance concerns But it really did not answer my concerns.

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• What could cause Django to start failing its own tests after an OS and Django reinstall?

  - by Macha

  I had to reinstall my OS, and so, I reinstalled django 1.1. Since reinstalling, when I run tests in my app, I get several failures from django.contrib.auth. Logs: http://dpaste.com/178153/ I asked on #django, and no one is too sure what the cause of the errors are. Some of my own code fails its tests, because it's not fully written yet, but that shouldn't cause django to fail it's core tests... I have included django.contrib.admin, which was mentioned as a possible cause.

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• How can I make a ViewController conform to multiple protocols?

  - by Moshe

  I want to include Core Location and I'm trying to follow this tutorial: http://www.mobileorchard.com/hello-there-a-corelocation-tutorial/ and I am using SDK 3.2.2. @interface MainViewController : UIViewController <FlipsideViewControllerDelegate>{ is the code right now.

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• Best way for user authentication on JavaEE 6 using JSF 2.0?

  - by ngeek

  I'm wondering what the current state of art recommendation is regarding user authentication for a web application making use of JSF 2.0 (and if any components do exist) and JEE6 core mechanisms (login/check permissions/logouts) with user information hold in a JPA entity. The Sun tutorial is a bit sparse on this (only handles servlets). This is without making use of a whole other framework, like Spring-Security (acegi), or Seam, but trying to stick hopefully with the new Java EE 6 platform (web profile) if possible. Thanks, Niko

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• Neo4j 1.9.4 (REST Server,CYPHER) performance issue

  - by user2968943

  I have Neo4j 1.9.4 installed on 24 core 24Gb ram (centos) machine and for most queries CPU usage spikes goes to 200% with only few concurrent requests. Domain: some sort of social application where few types of nodes(profiles) with 3-30 text/array properties and 36 relationship types with at least 3 properties. Most of nodes currently has ~300-500 relationships. Current data set footprint(from console): LogicalLogSize=4294907 (32MB) ArrayStoreSize=1675520 (12MB) NodeStoreSize=1342170 (10MB) PropertyStoreSize=1739548 (13MB) RelationshipStoreSize=6395202 (48MB) StringStoreSize=1478400 (11MB) which is IMHO really small. most queries looks like this one(with more or less WITH .. MATCH .. statements and few queries with variable length relations but the often fast): START targetUser=node({id}), currentUser=node({current}) MATCH targetUser-[contact:InContactsRelation]->n, n-[:InLocationRelation]->l, n-[:InCategoryRelation]->c WITH currentUser, targetUser,n, l,c, contact.fav is not null as inFavorites MATCH n<-[followers?:InContactsRelation]-() WITH currentUser, targetUser,n, l,c,inFavorites, COUNT(followers) as numFollowers RETURN id(n) as id, n.name? as name, n.title? as title, n._class as _class, n.avatar? as avatar, n.avatar_type? as avatar_type, l.name as location__name, c.name as category__name, true as isInContacts, inFavorites as isInFavorites, numFollowers it runs in ~1s-3s(for first run) and ~1s-70ms (for consecutive and it depends on query) and there is about 5-10 queries runs for each impression. Another interesting behavior is when i try run query from console(neo4j) on my local machine many consecutive times(just press ctrl+enter for few seconds) it has almost constant execution time but when i do it on server it goes slower exponentially and i guess it somehow related with my problem. Problem: So my problem is that neo4j is very CPU greedy(for 24 core machine its may be not an issue but its obviously overkill for small project). First time i used AWS EC2 m1.large instance but over all performance was bad, during testing, CPU always was over 100%. Some relevant parts of configuration: neostore.nodestore.db.mapped_memory=1280M wrapper.java.maxmemory=8192 note: I already tried configuration where all memory related parameters where HIGH and it didn't worked(no change at all). Question: Where to digg? configuration? scheme? queries? what i'm doing wrong? if need more info(logs, configs) just ask ;)

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• jquery masonry on ul with nested ul

  - by Adam Wright

  I'm trying to create a footer nav of a sitemap with levels nested within each other. i want to use masonry so the padding and margin is consistant and not changed depending on nested items. its firing masonry but its adding the relative style to the nested ul if i change the masonry call to select just the first() ul then nested li appear on one line. any ideas? <div id="links"> <ul ><li class="box"><a href="/Industries.aspx" >Industries</a></li><li class="box"><a href="/Services.aspx" >Services</a></li><li class="box"><a href="/Quality---Regulatory.aspx" >Quality &amp; Regulatory</a></li><li class="box"><a href="/About.aspx" >About</a><ul ><li class="box"><a href="/About/Our-Story.aspx" >Our Story</a></li><li class="box"><a href="/About/Our-Mission.aspx" >Our Mission</a></li><li class="box"><a href="/About/Our-Core-Values.aspx" >Our Core Values</a></li></ul></li><li class="box"><a href="/News.aspx" >News</a><ul ><li class="box"><a href="/News/Events.aspx" >Events</a></li></ul></li><li class="box"><a href="/Careers.aspx" >Careers</a></li><li class="box"><a href="/Contact.aspx" >Contact</a></li><li class="box"><a href="/tests.aspx" >tests</a></li></ul> </div> <script type="text/javascript"> $('#links ul').masonry({ singleMode: true, // Disables measuring the width of each floated element. // Set to true if floated elements have the same width. // default: false columnWidth: 182, // Width in pixels of 1 column of your grid. // default: outer width of the first floated element. itemSelector: '.box:visible', // Additional selector to specify which elements inside // the wrapping element will be rearranged. // Required for Infinite Scroll with window resizing. resizeable: true, // Binds a Masonry call to window resizes // so layout appears fluid. // default: true animate: false, // Animates layout rearrangements. // default: false saveOptions: true // Masonry will use the options from previous Masonry // calls by default, so you only have to enter in options once // default: true }); </script>

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• Country/State Dropdown in CakePHP

  - by raheelonline

  How do i deal with dependent combo boxes in the views with the form helper. For example: Country Select Box (Choosing a country shall filter out the states of the selected country) States Select Box This should happen with the help of Javascript / Jquery etc. I came across an example for the same with Cake's core AJAX helper but it would be very nice if someone can help with a Javascript example. Thanks

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• Hidden features of Clojure

  - by danlei

  Which lesser-known but useful features of Clojure do you find yourselves using? Feel free to share little tricks and idioms, but try to restrict yourselves to Core and Contrib. I found some really interesting information in answers to these similar questions: Hidden features of Haskell Hidden features of Python Hidden features of Java Hidden features of C There are many more "Hidden feature" questions for other languages, so I thought it would be nice to have one for Clojure, too.

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• NonUniqueObjectException during DAO integration test?

  - by HDave

  I have a JPA/Hibernate application and am trying to get it to run against H2 and MySQL. Currently I am using Atomikos for transactions and C3P0 for connection pooling. Despite my best efforts my DAO integration tests are failing with org.hibernate.NonUniqueObjectException. I do tend to re-use the same object (same ID even) over and over for all the different tests and I am sure that is the cause, but I can see in the logs that Spring Test and Atomikos are clearly rolling back the transaction associated with each test method. I would have thought the rollback would have also cleared the persistence context too. On a hunch, I added an a call to dao.clear() at the beginning of the faulty test methods and the problem went away!! Rollback doesn't clear the persistence context...hmmm.... Not sure if this is relevant, but I see a possible autocommit setting problem in the log file: [20100613 23:06:34] DEBUG [main] SessionFactoryImpl.(242) | instantiating session factory with properties: .....edited for brevity.... hibernate.connection.autocommit=true, ....more stuff follows Because I am using connection pooling, I figure that Hibernate is where I'll have to indicate I want autocommit off. I found the autocommit property documented here and I put it in my EntityManagerFactory config as follows: <bean id="myappTestLocalEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="myapp-core" /> <property name="persistenceUnitPostProcessors"> <bean class="com.myapp.core.persist.util.JtaPersistenceUnitPostProcessor"> <property name="jtaDataSource" ref="myappPersistTestJdbcDataSource" /> </bean> </property> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="showSql" value="true" /> <property name="database" value="$DS{hibernate.database}" /> <property name="databasePlatform" value="$DS{hibernate.dialect}" /> </bean> </property> <property name="jpaProperties"> <props> <prop key="hibernate.transaction.factory_class">com.atomikos.icatch.jta.hibernate3.AtomikosJTATransactionFactory</prop> <prop key="hibernate.transaction.manager_lookup_class">com.atomikos.icatch.jta.hibernate3.TransactionManagerLookup</prop> <prop key="hibernate.connection.autocommit">false</prop> <prop key="hibernate.format_sql">true"</prop> <prop key="hibernate.use_sql_comments">true</prop> </property> </bean>

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• CUDA SDK compilation error

  - by ZeroDivide

  I am in the process of setting up a CUDA workstation. Platform specs: Intel Core 2 Duo Nvidia GTX 280 Fedora 10 GCC version 4.3.2 I have installed the developer driver, toolkit, and the SDK. When I try to compile the SDK example code I get the following errors: make[1]: * [obj/i386/release/cutil.cpp.o] Error 1 make: * [lib/libcutil.so] Error 2 I think this means that I am missing a library file but I'm not sure.

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• Can't modify constant item in scalar assignment

  - by joe

  sub new { my $class = shift; my $ldap_obj = Net::LDAP->new( 'test.company.com' ) or die "$@"; my $self = { _ldap = $ldap_obj, _dn ='dc=users,dc=ldap,dc=company,dc=com', _dn_login = 'dc=login,dc=ldap,dc=company,dc=com', _description ='company', }; # Print all the values just for clarification. bless $self, $class; return $self; } what is wrong on this code : i got this error Can't modify constant item in scalar assignment at Core.pm line 12, near "$ldap_obj,"

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• Why is ARG_MAX not defined via limits.h?

  - by Josh Matthews

  On Fedora Core 7, I'm writing some code that relies on ARG_MAX. However, even if I #include <limits.h>, the constant is still not defined. My investigations show that it's present in <sys/linux/limits.h>, but this is supposed to be portable across Win32/Mac/Linux, so directly including it isn't an option. What's going on here?

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• How this pthread actually works?

  - by user289013

  I am actually on my project on compiler with SMP, and want to code with pthreads and heard about many parallel things open mpi and so on, So to start with how this thread is allocated to core while calling pthread,Is there any way to give threads to different cores by pthreads?

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• Setting Java 1.6 as the default on Mac OS X 10.5.8

  - by Eyvind

  How can I set Java 1.6 to be the default for my MacBook Pro Intel Core 2 Duo with OS X 10.5.8? I have installed the latest software update, and dragged the Java SE 6 64-bit choice to the top in the "Java Preferences" application (and even rebooted), but still, on the command line, java -version responds with: java version "1.5.0_24" Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_24-b02-357-9M3165) Java HotSpot(TM) Client VM (build 1.5.0_24-149, mixed mode, sharing) Any ideas?

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• Django approximate matching of unicode strings with ascii equivalents

  - by c

  I have the following model and instance: class Bashable(models.Model): name = models.CharField(max_length=100) >>> foo = Bashable.objects.create(name=u"piñata") Now I want to be able to search for objects, but using ascii characters rather than unicode, something like this: >>> Bashable.objects.filter(name__lookslike="pinata") Is there a way in Django to do this sort of approximate string matching, using ascii stand-ins for the unicode characters in the database? Here is a related question, but for Apple's Core Data.

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• python distutils does not include data_files

  - by StackUnderflow

  I am new to distutils.. I am trying to include few data files along with the package.. here is my code.. from distutils.core import setup setup(name='Scrapper', version='1.0', description='Scrapper', packages=['app', 'db', 'model', 'util'], data_files=[('app', ['app/scrapper.db'])] ) The zip file created after executing python setup.py sdist does not include the scrapper.db file. I have scrapper.db file in the app directory.. thanks for the help.

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• some pointer to understanding GCC source code

  - by user299570

  hi, I'm student working on optimizing GCC for multi-core processor. I tried going through the source code, it is difficult to follow through it since I need to add some code to the back end. Can anyone suggest some good resource which explains the code flow through the different phases. Also suggest some development environment for debugging GCC mainly to step through the code. Is it possible on windows?

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• Fastest inline-assembly spinlock

  - by sigvardsen

  I'm writing a multithreaded application in c++, where performance is critical. I need to use a lot of locking while copying small structures between threads, for this I have chosen to use spinlocks. I have done some research and speed testing on this and I found that most implementations are roughly equally fast: Microsofts CRITICAL_SECTION, with SpinCount set to 1000, scores about 140 time units Implementing this algorithm with Microsofts InterlockedCompareExchange scores about 95 time units Ive also tried to use some inline assembly with __asm {} using something like this code and it scores about 70 time units, but I am not sure that a proper memory barrier has been created. Edit: The times given here are the time it takes for 2 threads to lock and unlock the spinlock 1,000,000 times. I know this isn't a lot of difference but as a spinlock is a heavily used object, one would think that programmers would have agreed on the fastest possible way to make a spinlock. Googling it leads to many different approaches however. I would think this aforementioned method would be the fastest if implemented using inline assembly and using the instruction CMPXCHG8B instead of comparing 32bit registers. Furthermore memory barriers must be taken into account, this could be done by LOCK CMPXHG8B (I think?), which guarantees "exclusive rights" to the shared memory between cores. At last [some suggests] that for busy waits should be accompanied by NOP:REP that would enable Hyper-threading processors to switch to another thread, but I am not sure whether this is true or not? From my performance-test of different spinlocks, it is seen that there is not much difference, but for purely academic purpose I would like to know which one is fastest. However as I have extremely limited experience in the assembly-language and with memory barriers, I would be happy if someone could write the assembly code for the last example I provided with LOCK CMPXCHG8B and proper memory barriers in the following template: __asm { spin_lock: ;locking code. spin_unlock: ;unlocking code. }

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