From: Ingo Molnar <mingo@kernel.org>
To: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Michel Lespinasse <walken@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 05/31] x86/mm: Reduce tlb flushes from ptep_set_access_flags()
Date: Fri, 26 Oct 2012 15:26:01 +0200 [thread overview]
Message-ID: <20121026132601.GC9886@gmail.com> (raw)
In-Reply-To: <508A8D31.9000106@redhat.com>
* Rik van Riel <riel@redhat.com> wrote:
> On 10/26/2012 08:48 AM, Andi Kleen wrote:
> >Michel Lespinasse <walken@google.com> writes:
> >
> >>On Thu, Oct 25, 2012 at 9:23 PM, Linus Torvalds
> >><torvalds@linux-foundation.org> wrote:
> >>>On Thu, Oct 25, 2012 at 8:57 PM, Rik van Riel <riel@redhat.com> wrote:
> >>>>
> >>>>That may not even be needed. Apparently Intel chips
> >>>>automatically flush an entry from the TLB when it
> >>>>causes a page fault. I assume AMD chips do the same,
> >>>>because flush_tlb_fix_spurious_fault evaluates to
> >>>>nothing on x86.
> >>>
> >>>Yes. It's not architected as far as I know, though. But I agree, it's
> >>>possible - even likely - we could avoid TLB flushing entirely on x86.
> >>
> >>Actually, it is architected on x86. This was first described in the
> >>intel appnote 317080 "TLBs, Paging-Structure Caches, and Their
> >>Invalidation", last paragraph of section 5.1. Nowadays, the same
> >>contents are buried somewhere in Volume 3 of the architecture manual
> >>(in my copy: 4.10.4.1 Operations that Invalidate TLBs and
> >>Paging-Structure Caches)
> >
> > This unfortunately would only work for processes with no
> > threads because it only works on the current logical CPU.
>
> That is fine.
>
> Potentially triggering a spurious page fault on
> another CPU is bound to be better than always
> doing a synchronous remote TLB flush, waiting
> for who knows how many CPUs to acknowledge the
> IPI...
The other killer is the fundamental IPI delay - which makes it
'invisible' to regular profiling and makes it hard to analyze.
So yes, even the local flush is a win, a major one - and the
flush-less one is likely a win too, because INVLPG has some
TLB-cache-walking costs.
Rik, mind sending an updated patch that addresses Linus's
concerns, or should I code it up if you are busy?
We can also certainly try the second patch, but I'd do it at the
end of the series, to put some tree distance between the two
patches, to not concentrate regression risks too tightly in the
Git space, to help out with hard to bisect problems...
Thanks,
Ingo
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next prev parent reply other threads:[~2012-10-26 13:26 UTC|newest]
Thread overview: 135+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-25 12:16 [PATCH 00/31] numa/core patches Peter Zijlstra
2012-10-25 12:16 ` [PATCH 01/31] sched, numa, mm: Make find_busiest_queue() a method Peter Zijlstra
2012-10-25 12:16 ` [PATCH 02/31] sched, numa, mm: Describe the NUMA scheduling problem formally Peter Zijlstra
2012-11-01 9:56 ` Mel Gorman
2012-11-01 13:13 ` Rik van Riel
2012-10-25 12:16 ` [PATCH 03/31] mm/thp: Preserve pgprot across huge page split Peter Zijlstra
2012-11-01 10:22 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 04/31] x86/mm: Introduce pte_accessible() Peter Zijlstra
2012-10-25 20:10 ` Linus Torvalds
2012-10-26 6:24 ` [PATCH 04/31, v2] " Ingo Molnar
2012-11-01 10:42 ` [PATCH 04/31] " Mel Gorman
2012-10-25 12:16 ` [PATCH 05/31] x86/mm: Reduce tlb flushes from ptep_set_access_flags() Peter Zijlstra
2012-10-25 20:17 ` Linus Torvalds
2012-10-26 2:30 ` Rik van Riel
2012-10-26 2:56 ` Linus Torvalds
2012-10-26 3:57 ` Rik van Riel
2012-10-26 4:23 ` Linus Torvalds
2012-10-26 6:42 ` Ingo Molnar
2012-10-26 12:34 ` Michel Lespinasse
2012-10-26 12:48 ` Andi Kleen
2012-10-26 13:16 ` Rik van Riel
2012-10-26 13:26 ` Ingo Molnar [this message]
2012-10-26 13:28 ` Ingo Molnar
2012-10-26 18:44 ` [PATCH 1/3] x86/mm: only do a local TLB flush in ptep_set_access_flags() Rik van Riel
2012-10-26 18:49 ` Linus Torvalds
2012-10-26 19:16 ` Rik van Riel
2012-10-26 19:18 ` Linus Torvalds
2012-10-26 19:21 ` Rik van Riel
2012-10-29 15:23 ` Rik van Riel
2012-12-21 9:57 ` trailing flush_tlb_fix_spurious_fault in handle_pte_fault (was Re: [PATCH 1/3] x86/mm: only do a local TLB flush in ptep_set_access_flags()) Vineet Gupta
2012-10-26 18:45 ` [PATCH 2/3] x86,mm: drop TLB flush from ptep_set_access_flags Rik van Riel
2012-10-26 21:12 ` Alan Cox
2012-10-27 3:49 ` Rik van Riel
2012-10-27 10:29 ` Ingo Molnar
2012-10-27 13:40 ` Rik van Riel
2012-10-29 16:57 ` Borislav Petkov
2012-10-29 17:06 ` Linus Torvalds
2012-11-17 14:50 ` Borislav Petkov
2012-11-17 14:56 ` Linus Torvalds
2012-11-17 15:17 ` Borislav Petkov
2012-11-17 15:24 ` Rik van Riel
2012-11-17 21:53 ` Shentino
2012-11-18 15:29 ` Michel Lespinasse
2012-10-26 18:46 ` [PATCH 3/3] mm,generic: only flush the local TLB in ptep_set_access_flags Rik van Riel
2012-10-26 18:48 ` Linus Torvalds
2012-10-26 18:53 ` Linus Torvalds
2012-10-26 18:57 ` Rik van Riel
2012-10-26 19:16 ` Linus Torvalds
2012-10-26 19:33 ` [PATCH -v2 " Rik van Riel
2012-10-26 13:23 ` [PATCH 05/31] x86/mm: Reduce tlb flushes from ptep_set_access_flags() Michel Lespinasse
2012-10-26 17:01 ` Linus Torvalds
2012-10-26 17:54 ` Rik van Riel
2012-10-26 18:02 ` Linus Torvalds
2012-10-26 18:14 ` Rik van Riel
2012-10-26 18:41 ` Linus Torvalds
2012-10-25 12:16 ` [PATCH 06/31] mm: Only flush the TLB when clearing an accessible pte Peter Zijlstra
2012-10-25 12:16 ` [PATCH 07/31] sched, numa, mm, s390/thp: Implement pmd_pgprot() for s390 Peter Zijlstra
2012-11-01 10:49 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 08/31] sched, numa, mm, MIPS/thp: Add pmd_pgprot() implementation Peter Zijlstra
2012-10-25 12:16 ` [PATCH 09/31] mm/pgprot: Move the pgprot_modify() fallback definition to mm.h Peter Zijlstra
2012-10-25 12:16 ` [PATCH 10/31] mm/mpol: Remove NUMA_INTERLEAVE_HIT Peter Zijlstra
2012-10-25 20:58 ` Andi Kleen
2012-10-26 7:59 ` Ingo Molnar
2012-10-25 12:16 ` [PATCH 11/31] mm/mpol: Make MPOL_LOCAL a real policy Peter Zijlstra
2012-11-01 10:58 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 12/31] mm/mpol: Add MPOL_MF_NOOP Peter Zijlstra
2012-11-01 11:10 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 13/31] mm/mpol: Check for misplaced page Peter Zijlstra
2012-10-25 12:16 ` [PATCH 14/31] mm/mpol: Create special PROT_NONE infrastructure Peter Zijlstra
2012-11-01 11:51 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 15/31] mm/mpol: Add MPOL_MF_LAZY Peter Zijlstra
2012-11-01 12:01 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 16/31] numa, mm: Support NUMA hinting page faults from gup/gup_fast Peter Zijlstra
2012-10-25 12:16 ` [PATCH 17/31] mm/migrate: Introduce migrate_misplaced_page() Peter Zijlstra
2012-11-01 12:20 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 18/31] mm/mpol: Use special PROT_NONE to migrate pages Peter Zijlstra
2012-10-25 12:16 ` [PATCH 19/31] sched, numa, mm: Introduce tsk_home_node() Peter Zijlstra
2012-11-01 13:48 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 20/31] sched, numa, mm/mpol: Make mempolicy home-node aware Peter Zijlstra
2012-11-01 13:58 ` Mel Gorman
2012-11-01 14:10 ` Don Morris
2012-10-25 12:16 ` [PATCH 21/31] sched, numa, mm: Introduce sched_feat_numa() Peter Zijlstra
2012-11-01 14:00 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 22/31] sched, numa, mm: Implement THP migration Peter Zijlstra
2012-11-01 14:16 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 23/31] sched, numa, mm: Implement home-node awareness Peter Zijlstra
2012-11-01 15:06 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 24/31] sched, numa, mm: Introduce last_nid in the pageframe Peter Zijlstra
2012-11-01 15:17 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 25/31] sched, numa, mm/mpol: Add_MPOL_F_HOME Peter Zijlstra
2012-10-25 12:16 ` [PATCH 26/31] sched, numa, mm: Add fault driven placement and migration policy Peter Zijlstra
2012-10-25 20:53 ` Linus Torvalds
2012-10-26 7:15 ` Ingo Molnar
2012-10-26 13:50 ` Ingo Molnar
2012-10-26 14:11 ` Peter Zijlstra
2012-10-26 14:14 ` Ingo Molnar
2012-10-26 16:47 ` Linus Torvalds
2012-10-30 19:23 ` Rik van Riel
2012-11-01 15:40 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 27/31] sched, numa, mm: Add credits for NUMA placement Peter Zijlstra
2012-10-25 12:16 ` [PATCH 28/31] sched, numa, mm: Implement constant, per task Working Set Sampling (WSS) rate Peter Zijlstra
2012-11-01 15:48 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 29/31] sched, numa, mm: Add NUMA_MIGRATION feature flag Peter Zijlstra
2012-10-25 12:16 ` [PATCH 30/31] sched, numa, mm: Implement slow start for working set sampling Peter Zijlstra
2012-11-01 15:52 ` Mel Gorman
2012-10-25 12:16 ` [PATCH 31/31] sched, numa, mm: Add memcg support to do_huge_pmd_numa_page() Peter Zijlstra
2012-10-26 9:07 ` [PATCH 00/31] numa/core patches Zhouping Liu
2012-10-26 9:08 ` Peter Zijlstra
2012-10-26 9:20 ` Ingo Molnar
2012-10-26 9:41 ` Zhouping Liu
2012-10-26 10:20 ` Zhouping Liu
2012-10-26 10:24 ` Ingo Molnar
2012-10-28 17:56 ` Johannes Weiner
2012-10-29 2:44 ` Zhouping Liu
2012-10-29 6:50 ` [PATCH] sched, numa, mm: Add memcg support to do_huge_pmd_numa_page() Ingo Molnar
2012-10-29 8:24 ` Johannes Weiner
2012-10-29 8:36 ` Zhouping Liu
2012-10-29 11:15 ` Ingo Molnar
2012-10-30 6:29 ` [PATCH 00/31] numa/core patches Zhouping Liu
2012-10-31 0:48 ` Johannes Weiner
2012-10-31 7:26 ` Hugh Dickins
2012-10-31 13:15 ` Zhouping Liu
2012-10-31 17:31 ` Hugh Dickins
2012-11-01 13:41 ` Hugh Dickins
2012-11-02 3:23 ` Zhouping Liu
2012-11-02 23:06 ` Hugh Dickins
2012-10-30 12:20 ` Mel Gorman
2012-10-30 15:28 ` Andrew Morton
2012-10-30 16:59 ` Mel Gorman
2012-11-03 11:04 ` Alex Shi
2012-11-03 12:21 ` Mel Gorman
2012-11-10 2:47 ` Alex Shi
2012-11-12 9:50 ` Mel Gorman
2012-11-09 8:51 ` Rik van Riel
2012-11-05 17:11 ` Srikar Dronamraju
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