systemwide profiling of string functionss

Ondrej Bilka neleai@seznam.cz
Wed Oct 31 17:34:00 GMT 2012


On Wed, Oct 31, 2012 at 01:03:46AM +0100, Ondrej Bilka wrote:
> Hello,
> 
> I looked how are string functions used and wrote simple library for profiling. It can be LD_PRELOADed per application or systemwide.
> 
> Current version is at 
> http://kam.mff.cuni.cz/~ondra/benchmark_string/profile/string_profile.tar.bz2
> 
> As example I profiled glibc compilation and results are here: 
> http://kam.mff.cuni.cz/~ondra/benchmark_string/profile/result.html 
> 
Which had bug that I fixed now. 

When compiling with gcc most string functions spend most of their time on strings that are at most 50 characters long. This  information changes way how they should be optimized.

I want to do measurements also in real world setting. I plan to add sampling by selecting variant at random. 
However it has problem that I cant distinguish rtld calls from normal calls and not use sse there.

I will show how it applies to strn?len implementation tomorrow.



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