Messages in this thread | | | Date | Fri, 1 Nov 2013 10:21:48 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's |
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* Neil Horman <nhorman@tuxdriver.com> wrote:
> Prefetch and simluated adcx/adox from above: > Performance counter stats for './test.sh' (20 runs): > > 35,704,331 L1-dcache-load-misses ( +- 0.07% ) [75.00%] > 0 L1-dcache-prefetches [75.00%] > 19,751,409,264 cycles # 0.000 GHz ( +- 0.59% ) [75.00%] > 34,850,056 branch-misses ( +- 1.29% ) [75.00%] > > 7.768602160 seconds time elapsed ( +- 1.38% )
btw., you might also want to try measuring only the basics:
-e cycles -e instructions -e branches -e branch-misses
that should give you 100% in the last column and should also allow you to double check whether all the PMU counts are correct: is it the expected number of instructions, expected number of branches, expected number of branch-misses, etc.
Then you can remove branch stats and add just L1-dcache stats - and still be 100% covered:
-e cycles -e instructions -e L1-dcache-loads -e L1-dcache-load-misses
etc.
Just so that you can trust what the PMU tells you. Prefetch counts are sometimes off, they might include speculative activities, etc.
Thanks,
Ingo
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