Messages in this thread | | | Date | Mon, 01 Nov 2010 14:36:38 +0900 | From | Hitoshi Mitake <> | Subject | Re: [PATCH 2/2] perf bench: add x86-64 specific benchmarks to perf bench mem memcpy |
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On 2010年10月31日 04:23, Ingo Molnar wrote: > > * Hitoshi Mitake<mitake@dcl.info.waseda.ac.jp> wrote: > >> This patch adds new file: mem-memcpy-x86-64-asm.S >> for x86-64 specific memcpy() benchmarking. >> Added new benchmarks are, >> x86-64-rep: memcpy() implemented with rep instruction >> x86-64-unrolled: unrolled memcpy() >> >> Original idea of including the source files of kernel >> for benchmarking is suggested by Ingo Molnar. >> This is more effective than write-once programs for quantitative >> evaluation of in-kernel, little and leaf functions called high frequently. >> Because perf bench is in kernel source tree and executing it >> on various hardwares, especially new model CPUs, is easy. >> >> This way can also be used for other functions of kernel e.g. checksum functions. >> >> Example of usage on Core i3 M330: >> >> | % ./perf bench mem memcpy -l 500MB >> | # Running mem/memcpy benchmark... >> | # Copying 500MB Bytes from 0x7f911f94c010 to 0x7f913ed4d010 ... >> | >> | 578.732506 MB/Sec >> | % ./perf bench mem memcpy -l 500MB -r x86-64-rep >> | # Running mem/memcpy benchmark... >> | # Copying 500MB Bytes from 0x7fb4b6fe4010 to 0x7fb4d63e5010 ... >> | >> | 738.184980 MB/Sec >> | % ./perf bench mem memcpy -l 500MB -r x86-64-unrolled >> | # Running mem/memcpy benchmark... >> | # Copying 500MB Bytes from 0x7f6f2e668010 to 0x7f6f4da69010 ... >> | >> | 767.483269 MB/Sec >> >> This shows clearly that unrolled memcpy() is efficient >> than rep version and glibc's one :) > > Hey, really cool output :-) > > Might also make sense to measure Ma Ling's patched version?
Does Ma Ling's patched version mean,
http://marc.info/?l=linux-kernel&m=128652296500989&w=2
the memcpy applied the patch of the URL? (It seems that this patch was written by Miao Xie.)
I'll include the result of patched version in the next post.
> >> # checkpatch.pl warns about two externs in bench/mem-memcpy.c >> # added by this patch. But I think it is no problem. > > You should put these: > > +#ifdef ARCH_X86_64 > +extern void *memcpy_x86_64_unrolled(void *to, const void *from, size_t len); > +extern void *memcpy_x86_64_rep(void *to, const void *from, size_t len); > +#endif > > into a .h file - a new one if needed. > > That will make both checkpatch and me happier ;-) >
OK, I'll separate these files.
BTW, I found really interesting evaluation result. Current results of "perf bench mem memcpy" include the overhead of page faults because the measured memcpy() is the first access to allocated memory area.
I tested the another version of perf bench mem memcpy, which does memcpy() before measured memcpy() for removing the overhead come from page faults.
And this is the result:
% ./perf bench mem memcpy -l 500MB -r x86-64-unrolled # Running mem/memcpy benchmark... # Copying 500MB Bytes from 0x7f19d488f010 to 0x7f19f3c90010 ...
4.608340 GB/Sec
% ./perf bench mem memcpy -l 500MB # Running mem/memcpy benchmark... # Copying 500MB Bytes from 0x7f696c3cc010 to 0x7f698b7cd010 ...
4.856442 GB/Sec
% ./perf bench mem memcpy -l 500MB -r x86-64-rep # Running mem/memcpy benchmark... # Copying 500MB Bytes from 0x7f45d6cff010 to 0x7f45f6100010 ...
6.024445 GB/Sec
The relation of scores reversed! I cannot explain the cause of this result, and this is really interesting phenomenon.
So I'd like to add new command line option, like "--pre-page-faults" to perf bench mem memcpy, for doing memcpy() before measured memcpy().
How do you think about this idea?
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