Any way to profile code for cache behavior? - c++

As the title says I'd like to somehow get the cache behavior of my code. I'm running Windows 7 64-bit edition, compiling on Visual Studio 2008 Professional Edition, compiling C++ code.
I understand that there's Valgrind under Linux, but are there any free alternatives I could use, or methods otherwise?

VTune will give you pretty detailed cache and pipeline analysis. It's not cheap though. I believe some level/edition of VS (I remember it was "team edition" on XP) had a decent profiler.

Try AQTime. I'm pretty sure that some of it options include cache profiling.

Related

Visual Studio C++ performance vs Intel C++ compiler 15

Visual Studio 2015 has got a lot of changes on the C++ compiler side and I'm looking for a benchmark/performance comparison between the Intel C++ compiler and Visual Studio 2015 !
About performance, I mean the performance of the generated code, something like this : https://software.intel.com/en-us/c-compilers/iss
Is there an interest to use the Intel C++ compiler ? Will it produce faster code ?
Thanks
Few year ago, i did some tests on a mac-pro with intel proc.
Results:
icc+linux
vc+win
icc+win
gcc+linux
icc+linux was the very best.
vc+win, icc+win were pretty close.
Explanation: the more the software editor can exploit assertion on the system+hardware, the more it can design a compiler generating fast running code.
Intel is the best because it can exploit its processor and the system (open source).
VC under windows works great too, they know their OS.
Now, this depends of the kind of software. If your program will load a lot of data from disk the best will certainly be vc+win (they have great implementation of internal buffers...). If your program is very multithreaded, icc+linux is gonna win for sure. These are only 2 examples I can talk about because I tested these use cases.
I compared ICC and VC on Windows, and they were very close in terms of performance. I was able to make ICC beat VC only by using the "profile guided optimization" feature.

how to find out what part of my code is slowing my c++ program

I wrote 2 versions of my program, wich is an evolutionary algorithm in c++. The first version is procedural and works fine and very fast. The second version is completely OOP, and the program finds results, but is very very slow (like 10 times slower than the 1st version). Is there a way to maybe measure time of segments of code inside loops or something like that? Any advice or idea would help.
Thanks in advance.
Use a profiler. Which one is best depends on the platform/operating environment; e.g. with g++ you can use gprof, or if you don't want to recompile you can use oprofile, assuming Linux. On Solaris you could use dtrace. On other platforms, such as Windows or Mac, add the tag for your platform to the question...
You need a profiler to find performance related issues in your program.
Depending on the Visual Studio edition, you have various levels of profiling support in your Visual Studio. If you're lucky enough to be at the Visual Studio Ultimate or Premium edition, you have very good profiling support built right in.
If you're on Visual Studio Express or Visual Studio Professional, there is sadly no profiling support built into Visual Studio, but you can use for example info at this link how to do it manually for free with those editions anyway.
Use a profiler. If you're compiling with gcc, look up gprof, for example.
For your particular case, I suggest downloading and using this tool: http://www.codersnotes.com/sleepy/
It is a very simple (but efficient) sampling profiler.
Just launch your app with Ctrl+F5 (release) in Visual Studio, run this program (Very Sleepy), double click your exe name, wait, and you will see a detailed report with function names.
For the next level, if needed, use VTune.
You can use the \callcap compiler flag in VS. You can read about it here.
Basically you can add this flag only for the .cpp file that you want to analyze, define the enter/exit functions, rebuild your app, and run it. I suggest you split the code you are trying to analyze (and suspecting of being slow) into functions, and then you can see which piece of code takes more time to execute.
It's a little more work, compared to an already available profiler, but it's worth giving it a try.

Using visual profiler

I have some code in CUDA that I want to profile.Unfortunately on the machine I work visual profiler does not work.Would it be possible that I am able to test the code on a visual profiler on some other machine or something like that?
(basically I am looking for a workaround so that I can find bottlenecks).
Use this guide: Profiling CUDA Applications on Windows with NVIDIA Compute Visual Profiler
Since an answer hasn't been accepted yet, I suggest giving the newest version of Visual Profiler a try.
The new NVIDIA Visual Profiler (v4.1) supports automated performance analysis to identify performance improvement opportunities in your application. It also links directly to the most useful sections of the Best Practices Guide for the issues it detects. The Visual Profiler is still available for free as part of the CUDA Toolkit on NVIDIA's developer web site: http://www.nvidia.com/getcuda.
If you're still not able to get it working, please file a bug via your (free) NVIDIA registered developer account so the team working on Visual Profiler can investigate further.

Need a c++ compiler to work with libraries (boost, ...)

Currently I`m using Visual Studio for writing code in C++. But it seems so weighty that I decided to switch for another one, preferably free, not so strict to system resources (I mean memory, of course) as VS to learn libraries, such as Boost and Qt. What compiler do you suggest?
I'd suggest using Visual Studio's compiler from the command-line. You get the same high-quality compiler, without the resource-hogging IDE.
Although the IDE is pretty good too, and probably worth the resources it uses.
Code::blocks is exactly what you are after. You can can download it here: http://www.codeblocks.org/downloads/5
Choose the version with the mingw compiler bundled with it (Windows port of GCC). You can switch between that and the VC++ compiler as and when you like.
Code::Blocks has all the stuff you want, debugger integration, code completion, class browser, todo list etc. etc. It even import visual C++ projects.
Don't use Dev C++ which has already been recommended. It's very very old and outdated.
If you want to learn unix tools download and install cygwin It's a good set of tools but a full install takes up 5 or 6 gigs because so much is included.
There is always Digital Mars. Also, you can freely download Microsoft WDK
which comes with their C/C++ compiler and command-line build system.
You will be hard-pressed to find an IDE as capable as MS VS. It is incredibly feature-rich.
However, if you just want command line compiling and linking it can do that too.
GCC is also an option.
Please note that you do not need another compiler or IDE to use boost libraries. I wouldn't replace Visual Studio with any other IDE/compiler, at least not on Windows. Installing Cygwin or SUA (better than Cygwin, closer to the Windows Kernel) will only be a pain just for what you are trying to reach.
Try to minimize the memory usage by disabling unnecessary things, keep the amount of open source files small, use an alternative to document explorer to find help (your browser on msdn will do). Besides that, I wouldn't call a few ten megabytes of memory a high usage. As long as it doesn't slow your system down there is not a real issue.
A better idea would be to upgrade your computer rather than to replace something powerful with something that you don't know.
Seriously there is no real alternative to Ms's compiler on Windows. All the others are OK if you can't spring for Visual Studio or if you are just doing hobbyist work. Cygwin can be a pain to deal with.
If you don't want the IDE as someone else suggested just use the command-line compiler.
I've found VS to be quite good for doing Boost + Qt work. Especially if you have the Qt + VS integration tool. You get a GUI designer and respectable Qt project management tools.
If you are looking for a compiler that uses fewer system resources than the MS ones, you'll probably find that most modern compilers that are able to compile a good part of or almost everything in Boost will be quite heavy on system resources, both processor usage and memory consumption. To a certain extent that's just par for the course when it comes to C++.
That said, I do like to have a second compiler around if I'm writing portable code as it's a lot easier to iron out portability issues when you can ensure that the code compiles in different environments. If you want to do all that on Windows, may Cygwin is worth a look. However it does seem that the GCC you get with Cygwin is not exactly what you'd call up to date.
The aforementioned Digital Mars compilers are well worth a look, Walter Bright (the guy behind them) has been writing C++ compilers for a long time and they're pretty good. I have used them off and on since the early nineties and I've always been happy with them. Not to mention that they always seemed noticeably faster than the Microsoft offerings, but I haven't got any recent measurements to back that up.
At the end of the day, most third-party tool vendors on Windows tend to target the MS environment so if you're writing C++ code professionally and need/want tools like leak detectors, you pretty much need to be able to build with the MS compilers, even if they aren't your main development environment.
I sugget , Netbeans.org
NetBeans IDE , download the Cygwin , follow one tutorial from http://www.netbeans.org for C++ confuguration at Netbeans IDE , just 2 steps.. and u are ok
autocomplete (faster than VS')
classes
and all... you want xD
It needs to mention about DevCpp. It is a simple UI wrap for gcc compiler (oh my, it is sounds like a tautology). It provides lightweight IDE but not so stable (so, its IntelliSense is somewhat buggy).
If you use Qt why not use their IDE, QtCreator, there is compiler, debugger and GUI designer. All comes in one nice package and works on Windows, Mac and Linux.
In my opinion it's better than Code::Blocks (also based on MinGW/GCC).

What are the differences between Visual C++ 6.0 and Visual C++ 2008?

What are the advantages/disadvantages between MS VS C++ 6.0 and MSVS C++ 2008?
The main reason for asking such a question is that there are still many decent programmers that prefer using the older version instead of the newest version.
Is there any reason the might prefer the older over the new?
Advantages of Visual Studio 2008 over Visual C++ 6.0:
Much more standards compliant C++ compiler, with better template handling
Support for x64 / mobile / XBOX targets
Improved STL implementation
Support for C++0x TR1 (smart pointers, regular expressions, etc)
Secure C runtime library
Improved code navigation
Improved debugger; possibility to run remote debug sessions
Better compiler optimizations
Many bug fixes
Faster builds on multi-core/multi-CPU systems
Improved IDE user interface, with many nice features
Improved macro support in the IDE; DTE allows access to more IDE methods and variables
Updated MFC library (in VS2008 Service Pack 1)
support for OPENMP (easy multithreading)(only in VS2008 pro.)
Disadvantages of moving to Visual Studio 2008:
The IDE is a lot slower than VS6
Intellisense still has performance issues (replacing it with VisualAssistX can help)
Side-by-side assemblies make app deployment much more problematic
The local (offline) MSDN library is extremely slow
As mentioned here, there's no profiler in the Professional version
In the spirit of Joel's recent blog post, I've combined some of the other answers posted into a single answer (and made this a community-owned post, so I won't gain rep from it). I hope you don't mind. Many thanks to Laur, NeARAZ, 17 of 26, me.yahoo.com, and everyone else who answered. -- ChrisN
Well, for one thing it may be because the executables built with MSVS 6 require only msvcrt.dll (C runtime) which is shipped with Windows now.
The MSVS 2008 executables need msvcrt9 shipped with them (or already installed).
Plus, you have a lot of OSS libraries already compiled for Windows 32 bit with the 6.0 C runtime, while for the 2008 C runtime you have to take the source and compile them yourself.
(most of those libraries are actually compiled with MinGW, which too uses the 6.0 C runtime - maybe that's another reason).
I would like to add that it's not the case that applications developed using Visual C++ 2008 must require more DLLs than those developed using Visual C++ 6.0. That's just the default project configuration.
If you go into your project properties, C/C++, Code Generation, then change your Runtime Library from Multi-threaded DLL and Multi-threaded Debug DLL (Release and Debug configurations) to Multi-threaded and Multi-threaded Debug, your application should then have fewer dependencies.
Off the top of my head, the advantages of the new Visual Studio are:
stricter adherence to standards
support for x64 / mobile / XBOX
targets
better compiler optimizations
(way) better template handling
improved debugger; possibility to
run remote debug sessions
improved IDE
improved macro support; DTE allows access to more IDE methods and variables
Disadvantages:
IDE seems slower
Intellisense still has performance
issues (replacing it with
VisualAssistX can help)
runtime not universally available
source control integration not up to
par (although in all fairness VC6
lacks this feature completely)
Did you know that MS VC6's implementation of the STL isn't thread-safe? In particular, the reference counting optimization in basic_string blows up even when compiled with the multi-threaded libraries.
http://support.microsoft.com/kb/813810
Besides the deployment mentioned above, the main advantage of MSVC 6.0 is speed. Because it is a 10 year old IDE it feels quite fast on a modern computer. The newer versions of Visual Studio offer more advanced features, but they come at a cost (complexity and slower speed).
But the biggest draw-back of MSVC 6.0 is its non-compliant C++-Compiler and Library. If you intend to do serious C++-Programming this is a show-stopper. If you only build MFC-Applications it is probably not much of a problem.
Visual C++ 6.0 integrates with memory tracking tools, such as Purify, HeapAgent, BoundsChecker and MemCheck, thoroughly and well since those memory tracking tools were actively maintained and aggressively sold after Visual C++ 6.0 came out.
However, since C++ has been out of vogue for a while, the companies that sell memory tracking tools still sell them but never update or integrate them with new Visual C++ versions, including Visual Studio 2008. So, using memory tracking tools with Visual Studio 2008 is frustrating, errorprone and, in some cases, impossible.
Since VC6 most of the focus of Visual Studio has been on C# and .NET, as well as other features, so some C++ old-timers see VC6 as the good old days. Things have improved in Visual Studio for C++ developers since those days, but not nearly as dramatically as for .NET users.
One way that VS2008 is significantly better than VC6 is that it can build C++ projects in parallel. This can result in significantly faster builds even on a single CPU system, but especially if you have multiple cores.
If you install all service packs for VS6 you still have a solid IDE/compiler combo. As a software developer who have to release products in the wild (over Internet) I don't want to o ship the VC++ runtimes and .NET framework everytime (I can't bundle them directly in my installer/executable, its forbidden by Microsoft). You know, several megabytes of runtimes to run kilobytes of code is kinda stupid. VC++ 6.0 only need your executable and 2 .DLL at best.
Also, debug runtimes cannot be distributed with VC++ .NET, not really good when I have a client which need to do some debugging of my products :)
There is in my opinion the major reasons why I still use VC++ 6.0, but the IDE itself is ugly (ie: no tabbing support). I usually bypass the IDE limitations by using codeblocks instead (CodeBlocks support CL.EXE/LINK.EXE for all VC++ versions)
Cobolfoo
Visual C++ 2008 is much more standards compliant (Visual Studio 6 doesn't support the C++ standard set in 1998).
VS2008 has better compiler (much more standards compliant, better optimizations, ...).
VS6 has much faster IDE. VS2008 IDE has many nice features, but it is a low slower than VS6.
Quick list of improvements you'll see going from 6.0 to 2008:
Many bug fixes
Better conformance to the C++ standard
Better compiler optimization
Improved UI (better intellisense, etc)
One thing that people sometimes forget is that VS 6.0 is over 10 years old now! At this point, I don't see how anyone would want to stick with it.
one tough thing we encountered was that "value" became a keyword.
Visual C++ 6 can be very buggy at times compared to 2008. Some things in particular:
Poor template support/oddities (for instance sometemplate<othertemplate<t>> not working, but sometemplate< othertemplate<t> > working)
Not standards compliant
Resource editor is rubbish ("blue lines" seem to move around randomly, among other things)
Only supports editing certain kinds of 8-bit bitmaps (I have to use imagemagick to convert bitmaps saved in paint.net to be able to be seen in picture resources)
Terrible support for working with read-only files / quirky sourcesafe integration.
Sometimes developing in VS6 feels like trying to get websites looking good in internet explorer 5.5