Messages in this thread | | | Date | Thu, 26 Feb 2015 09:58:13 +0000 | From | Catalin Marinas <> | Subject | Re: [LKP] [futex] 76835b0ebf8: -8.1% will-it-scale.per_thread_ops |
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On Thu, Feb 26, 2015 at 05:16:53AM +0000, Huang Ying wrote: > FYI, we noticed the below changes on > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > commit 76835b0ebf8a7fe85beb03c75121419a7dec52f0 ("futex: Ensure get_futex_key_refs() always implies a barrier") > > > testbox/testcase/testparams: lkp-wsx01/will-it-scale/performance-futex4 > > 0429fbc0bdc297d6 76835b0ebf8a7fe85beb03c751 > ---------------- -------------------------- > %stddev %change %stddev > \ | \ > 6314259 ± 0% -8.1% 5800079 ± 0% will-it-scale.per_thread_ops > 6274871 ± 0% -8.1% 5768747 ± 0% will-it-scale.per_process_ops
This was raised before but I'm not sure we can do much about it:
https://lkml.org/lkml/2014/10/26/189
It would be interesting to know the difference in performance with the code prior to commits b0c29f79ecea and 11d4616bd07f which optimised the futex code but missed a barrier.
-- Catalin
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