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I have program in C and I want to test performance of my code! But I want change and test again and again! I want to run all of test in exactly same condition(same memory available, in general same resource available).
I am developing on MacOS 10.9 but I need tool works on both mac an linux!
Could you suggest any?
Thanks!
You could use the time(1) command:
time yourprogram yourarguments....
and you could limit resources with e.g. setrlimit(2), concretely using the ulimit shell builtin. See this.
Notice that the operating system kernel is providing resources (and can be seen as a resource itself, or at least as a resource manager). So with different OSes you cannot have exactly the same resources (and conditions)! For instance, file systems and scheduling are different on Linux and on MacOSX, and they are an important resource provided and managed by the OS kernel.
in your case if performance means execution time, then simple shell script like
date
your c file execution
date
this will tell you the required output.
if you need actual performance (time,cpu,memory,etc) then on Linux sar utility can be used which will provide all the performance counters.
after which you can analyze the data and get the performance of your code
use profilers for your code which will tell you performance of your code with suggestions if any are present
use static code analyzers (feed your code as input to code analyzer which will tell you the performance of your code and possible enhancements)
Related
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I have been developing for Windows for a long time, mainly WinApi (and .Net).
I'v started learning basic Linux, and I have some questions regarding the differences:
In Windows I have barely used the C Standard library.
If I needed an API, I would search MSDN and find the appropriate library\function.
From what it seems like, in Linux the C Standard library is EVERYTHING.
All the code samples I have seen used the standard library (Instead of using some Linux internal functions, like a Linux "CreateFile").
Is this really how writing "proper" linux code is done ? Using the C standard library ?
If I wish to read a file, or allocate memory are fopen\malloc the way to go ?
If the answer to my first question is yes (And I guess it will be)
The C standard library is POWERLESS compared to the powerful WinApi.
Lets say I wish to get a list of running process (CreateToolhelp32Snapshot) or create a thread or a process (CreateThread\CreateProcess), How should I do that in Linux ?
Documentation.
In Windows, all I need can be found in MSDN.
If I have a "how do I do" question (Like the questions above) where should I go ?
Where is my main source of documentation.
Thanks a lot,
Michael.
Perhaps you've forgotten that the Standard C Library isn't environment-specific, it specifies least-common-denominator functionality among all systems that can run C programs, and C runs on systems that don't even have processes.
If you want an API that provides consistent common GUI/multithread/etc. APIs, pick a likely-looking GUI/multithread/etc. API. You might start with Qt, it's quite comprehensive and produces good-looking, near-native UIs on a host of systems.
It's not generally considered polite to point this out, but most questions that get asked publicly are asked by people who lack the discipline to do even simple research. Once people can do that, they don't need to ask very many, and that's why what you see is so ... trivial. You're past that. For more options, you could start here.
For more general-purpose tools, the top hit on a search for important linux tools might be helpful.
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I'm trying to do some learning with Linux kernel and as you all know there is nothing better than playing with the code itself, Can you please let me know which one of the Linux distros is the easiest to work with? In other words, As far as I know Ubuntu for example modify the kernel for their distro, so the question again, which distro is using the Linux kernel as is with no modification?
Appreciate your guidance.
When it comes to no-frills (no external patches to the kernel) have a look at Slackware. Or follow "Linux from Scratch", that's as bare-bones as it gets.
If you want to start playing with the Linux kernel, I'd recommend a distribution which makes it particularily easy to compile the kernel yourself. Although I cannot provide detailed guidance, Gentoo seems to do so (although gentoo has other drawbacks, I don't know a single person in real life who actually used gentoo for more than two years).
I would not try and look for distributions not modifying the kernel, it's probably not worth the effort. Patches will probably be minor compared to the overall size of the kernel.
You can easily run Ubuntu for example with a vanilla kernel by following https://wiki.ubuntu.com/KernelTeam/GitKernelBuild.
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I was making a little device that would have three buttons (like the ones at radioshack) and each preform its own action. These buttons and their actions would be controlled by a very small real time operating system that I would put on this device.
Would I need an ARM Processor in any way?
How would I put the real time operating system on the device?
What OS would I have to compile this on (ex. Ubuntu? Mac OS X? Windows 7?)?
Are there any examples of anyone doing this?
P.S. No prebuilt boards (ex. arduino). I would build the board myself.
Any feedback would be greatly appreciated!
Even if you don't want to use a prebuilt board in the finished product, I'd recommend getting a prebuilt board (like the Arduino), build your product, program it, test it, etc. while on the breadboard, and then simply rebuild it however you want, using the same hardware as you've been using.
That helps you out especially the next time you're building something, because you already have the prototype board and the toolchain ready to go.
Compiling your files can be done on any OS.
Enumerated version:
No, and I wouldn't even recommend using an ARM processor; but rather an Atmega328 or similar.
Using a programmer.
Any.
Probably millions, or at least hundreds of thousands of examples, yes.
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What open-source implementation(s) in C for a pthreads thread pool would you recommend ?
Additional points if this implementation is :
Light-weight: glib, APR, NSPR and others come with a big buy-in, I'd rather have just 2 files (header and implementation).
Tested on several platforms (Linux, BSD, Mac OS X, etc.).
Still maintained.
I worked on making something I'd be able to use and I've published it on github: it's unimaginably called threadpool.
If your goal is light-weight, then the last thing you want is a prewritten, super-general-purpose, high-level-abstraction-based implementation. Implementing a thread pool yourself, suited to your particular task, is fairly trivial, but you might also question whether you actually need a thread pool or whether you'd be fine just creating and destroying threads as needed.
Without knowing more details about your application, I can't give much more specific advice. But the tools you might find useful are:
Condition variables
Semaphores
A job queue protected by a mutex
POSIX message queues
Here is an implementation with these features:
ANSI C and POSIX compliant
Minimal but powerful API
Synchronisation from the user
Full documentation
I once used this, which isn't actually an official implementation per se. It does use pthreads as you requested, and should give you some ideas of what you need to do. (See threadpool.h, threadpool.c, threadpool_test.c, and the Makefile for instructions on how to compile.) You'll obviously have to do some refactoring as it's original intention is probably different than yours. It's commented rather well actually.
Even though this deviates from the original question, I'd also like to mention that the newest C standard, unofficially C1X (see wikipedia, hyperlink limit), has planned support for threads N1570 (google it, hyperlink limit again!) (7.31.15).
Some personal advice from my experience would be to make sure that your application can actually be run in parallel, and if the overhead of creating a new thread is so high that you can't live without a thread pool. Personally I've blundered on both these parts and I've actually ended up with implementations slower than my single threaded application. Also, you might want to be aware of different problems, including cache-lockouts and misses, which would actually degrade the performance of your application.
I'm probably blabbering on by now, but best of luck.
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I'd like to use a virtual machine like NekoVM into a small device but to build it, it requires Boehm GC, however there is no port of that GC to that small device so I was wondering if there is any alternative to it, something that could be done exclusively with C code?
I'd say your best option would be to port the GC to your platform, for which there are instructions (libgc porting instructions).
Additionally, it should be possible to swap out the GC implementation (NekoVM FAQ), see vm/alloc.c file.
EDIT:
Hopefully useful additional links: (untested)
Smieciuch Garbage Collector
libgcroots (based on libgc 7, abstracts architecture dependant bits)
Squirrel programming language
Perhaps you'd be better off with Lua, which has a very small but powerful virtual machine, has its own garbage collector built in, and runs on any platform that supports ANSI Standard C. With just a little effort you can even build Lua on a machine that lacks standard input and standard output. I have seen Lua running on an embedded device that was a small LCD touch screen with an embedded CPU stuck on the back. Neko is good work, but I think you'll find Lua every bit as satisfying.
I could suggest TinyGC (tinygc.sf.net) - an independent lightweight implementation of the BoehmGC targeting small devices. It is fully API-compatible (even more, binary compatible) with BoehmGC v7+ but only a small subset of the API is implemented (but sufficient for Java/GCJ-like memory management) and there is no automatic threads and static data roots registration. The latter, however, may require some efforts to make NekoVM work with it (i.e., call GC_register_my_thread() and GC_add_roots()).