Re: [PATCH RFC] x86: avoid atomic operation in test_and_set_bit_lock if possible

Andi Kleen
2011-03-24T20:42:18Z

Ingo Molnar <mingo@elte.hu> writes:
>
> One good way to see cache bounces is to run a misses/accesses ratio profile:
>
> perf top -e cache-misses -e cache-references --count-filter 10
>
> Note the two events: this runs a 'weighted' profile, you'll see (LLC)
> cache-misses of a function relative to cache-references it does, a
> misses/references ratio in essence.

If anyone does this on a Nehalem please only use 2.6.39-rc*+ which
includes the offcore patches. Anything before that will get you complete
bogus numbers.

BTW with Lin-Ming's memory latency profiling code you can do this much
more directly.

-Andi
--
ak@linux.intel.com -- Speaking for myself only