This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH] Fixes tree-loop-distribute-patterns issues


On Fri, 2013-06-21 at 04:00 +0200, OndÅej BÃlka wrote:
> I choose a O0 as lesser evil than having reference implementation twice
> faster depending what compiler you do use.
> 
> One solution is mandate to run benchmarks with fixed version of gcc and
> fixed flags.
> 
> Second variant could be have assemblies and regeneration script that would 
> be ran with specific gcc.

Yes you can try to find a niche where you hope you can compare stuff.
But you can as well just get all the measurements you can from people
out there -- with whatever version of gcc is available -- and take this
into account when drawing conclusions from the data.  That is, you'd
setup your machine learning in such a way that it looks a data and
checks whether there is high confidence for a certain conclusion (eg,
new version of code faster or not).  Confidence will be lower if, for
example, we see performance vary a lot with different versions of gcc,
but remain more or less unchanged when gcc versions don't differ; but if
performance varies independently of the gcc version, that's also useful
to know because it means we draw our conclusion from a wider set of
tests.  Likewise for other properties of the test environment such as
the CPU etc.

Obviously, right now I don't have a patch to do this.  But I believe we
need to keep this in mind.  This approach isn't rocket science either.
We already make use of it every day.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]