Messages in this thread | | | Subject | Re: More latency regressions with 2.6.11-rc4-RT-V0.7.39-02 | From | Lee Revell <> | Date | Wed, 23 Feb 2005 14:36:21 -0500 |
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On Wed, 2005-02-23 at 19:16 +0000, Hugh Dickins wrote: > On Wed, 23 Feb 2005, Lee Revell wrote: > > > > Did something change recently in the VM that made copy_pte_range and > > clear_page_range a lot more expensive? I noticed a reference in the > > "Page Table Iterators" thread to excessive overhead introduced by > > aggressive page freeing. That sure looks like what is going on in > > trace2. trace1 and trace3 look like big fork latencies associated with > > copy_pte_range. > > I'm just about to test this patch below: please give it a try: thanks... > > Ingo's patch to reduce scheduling latencies, by checking for lockbreak > in copy_page_range, was in the -VP and -mm patchsets some months ago; > but got preempted by the 4level rework, and not reinstated since. > Restore it now in copy_pte_range - which mercifully makes it easier.
Aha, that explains why all the latency regressions involve the VM subsystem.
Thanks, your patch fixes the copy_pte_range latency. Now zap_pte_range, which Ingo also fixed a few months ago, is the worst offender. Can this fix be easily ported too?
Lee
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