Messages in this thread | | | Subject | Re: [LKP] [futex] 76835b0ebf8: -12.1% will-it-scale.per_process_ops | From | Davidlohr Bueso <> | Date | Sun, 26 Oct 2014 19:26:01 -0700 |
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On Mon, 2014-10-27 at 10:18 +0800, kernel test robot wrote: > FYI, we noticed the below changes on > > commit 76835b0ebf8a7fe85beb03c75121419a7dec52f0 ("futex: Ensure get_futex_key_refs() always implies a barrier")
fwiw I was also able to reproduce similar results, with the hashing costing (unsurprisingly) around an extra ~10% with the new barrier, not much we can do about that. In any case these are pretty low level measurements so shouldn't impact too much. Additionally, any user that cares about performance will try to avoid incurring futex calls into kernel space.
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