David Chisnall wrote this message on Wed, May 13, 2015 at 09:27 +0100:
> On 13 May 2015, at 09:03, John-Mark Gurney <[email protected]> wrote:
> >
> > Poul-Henning Kamp wrote this message on Tue, May 12, 2015 at 06:31 +0000:
> >> --------
> >> In message <[email protected]>, John-Mark Gurney writes:
> >>
> >>> Also, you'd probably see even better performance by increasing the
> >>> size to 64k, [...]
> >>
> >> easy:
> >> 8K on 32bit
> >> 64k on 64bit
> >
> > Sounds good to me... Just for people who care... I did a quick set of
> > benchmarks on sha256.. This is using my preliminary patch to use sse4
> > optimized sha256... But this should be the same for others...
> >
> > The numbers in ministat output are the time in seconds it takes my
> > 3.4GHz AMD A10-5700 APU running HEAD to process a 512MB file, so lower
> > numbers are better.. I've processed them into easier to read format:
> > BUFSIZ: 145MB/sec
> > 8k: 193MB/sec
> > 16k: 198MB/sec
> > 64k: 202MB/sec
> > 128k: 202MB/sec
> > -t: 211MB/sec
>
> It looks like most of the benefit is gained at 16KB. Did you try running the
> benchmark with something else running at the same time to see if there is any
> advantage in trashing the caches a bit less (simple case, what happens if you
> run two instances of the same benchmark at once)?
>
> I suspect that you???re about right anyway - I recently did some tests while
> playing with JavaScript FFI generation with a multithreaded process
> JavaScript environment calling out to OpenSSL to do SHA calculations and
> having each of 8 threads reading in 128KB chunks gave the fastest performance
> (Core i7, 4 cores + hyperthreading), with only a negligible gain over 64KB.
> In all cases, the JavaScript implementation was significantly faster than the
> openssl tool, which used 8KB buffers.
Just in case anyone else wants to know how to run benchmarks
themselves.. Go into /usr/src/lib/libmd, edit mdXhl.c, and change
the occurence of BUFSIZ to what you want to test, say 64*1024, run:
make all && make install
and then you can run programs like sha256 -t, or:
for i in `jot 5 1`; do /usr/bin/time sha256 test.file ; done 2> XXX.times
Where test.file is populated maybe like:
dd if=/dev/urandom of=test.file bs=1m count=512
Then run:
ministat XXX.times YYY.times
to compare multiple results...
Happy benchmarking!
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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