From: Gerald Schaefer <gerald.schaefer@de.ibm.com>
To: Peter Xu <peterx@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Will Deacon <will@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 01/26] mm: Do page fault accounting in handle_mm_fault
Date: Wed, 24 Jun 2020 20:49:03 +0200 [thread overview]
Message-ID: <20200624204903.097a5a58@thinkpad> (raw)
In-Reply-To: <20200619160538.8641-2-peterx@redhat.com>
On Fri, 19 Jun 2020 12:05:13 -0400
Peter Xu <peterx@redhat.com> wrote:
[...]
> @@ -4393,6 +4425,38 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
> mem_cgroup_oom_synchronize(false);
> }
>
> + if (ret & VM_FAULT_RETRY)
> + return ret;
I'm wondering if this also needs a check and exit for VM_FAULT_ERROR.
In arch code (s390 and all others I briefly checked), the accounting
was skipped for VM_FAULT_ERROR case.
> +
> + /*
> + * Do accounting in the common code, to avoid unnecessary
> + * architecture differences or duplicated code.
> + *
> + * We arbitrarily make the rules be:
> + *
> + * - faults that never even got here (because the address
> + * wasn't valid). That includes arch_vma_access_permitted()
Missing "do not count" at the end of the first sentence?
> + * failing above.
> + *
> + * So this is expressly not a "this many hardware page
> + * faults" counter. Use the hw profiling for that.
> + *
> + * - incomplete faults (ie RETRY) do not count (see above).
> + * They will only count once completed.
> + *
> + * - the fault counts as a "major" fault when the final
> + * successful fault is VM_FAULT_MAJOR, or if it was a
> + * retry (which implies that we couldn't handle it
> + * immediately previously).
> + *
> + * - if the fault is done for GUP, regs wil be NULL and
wil -> will
Regards,
Gerald
next prev parent reply other threads:[~2020-06-24 18:49 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 16:05 [PATCH 00/26] mm: Page fault accounting cleanups Peter Xu
2020-06-19 16:05 ` [PATCH 01/26] mm: Do page fault accounting in handle_mm_fault Peter Xu
2020-06-24 18:49 ` Gerald Schaefer [this message]
2020-06-24 20:34 ` Peter Xu
2020-06-26 19:54 ` Gerald Schaefer
2020-06-26 21:53 ` Peter Xu
2020-06-26 22:27 ` Peter Xu
2020-06-19 16:05 ` [PATCH 02/26] mm/alpha: Use general page fault accounting Peter Xu
2020-06-19 16:05 ` [PATCH 03/26] mm/arc: " Peter Xu
2020-06-19 16:05 ` [PATCH 04/26] mm/arm: " Peter Xu
2020-06-19 16:05 ` [PATCH 05/26] mm/arm64: " Peter Xu
2020-06-19 16:05 ` [PATCH 06/26] mm/csky: " Peter Xu
2020-06-20 1:44 ` Guo Ren
2020-06-20 16:08 ` Peter Xu
2020-06-19 16:05 ` [PATCH 07/26] mm/hexagon: " Peter Xu
2020-06-19 16:05 ` [PATCH 08/26] mm/ia64: " Peter Xu
2020-06-19 16:05 ` [PATCH 09/26] mm/m68k: " Peter Xu
2020-06-19 16:05 ` [PATCH 10/26] mm/microblaze: " Peter Xu
2020-06-19 16:05 ` [PATCH 11/26] mm/mips: " Peter Xu
2020-06-25 8:28 ` Thomas Bogendoerfer
2020-06-19 16:05 ` [PATCH 12/26] mm/nds32: " Peter Xu
2020-06-19 16:12 ` [PATCH 13/26] mm/nios2: " Peter Xu
2020-06-19 16:12 ` [PATCH 14/26] mm/openrisc: " Peter Xu
2020-06-19 16:13 ` [PATCH 15/26] mm/parisc: " Peter Xu
2020-06-19 16:13 ` [PATCH 16/26] mm/powerpc: " Peter Xu
2020-06-19 16:13 ` [PATCH 17/26] mm/riscv: " Peter Xu
2020-06-19 16:13 ` [PATCH 18/26] mm/s390: " Peter Xu
2020-06-24 18:49 ` Gerald Schaefer
2020-06-24 20:40 ` Peter Xu
2020-06-19 16:13 ` [PATCH 19/26] mm/sh: " Peter Xu
2020-06-19 16:13 ` [PATCH 20/26] mm/sparc32: " Peter Xu
2020-06-19 16:13 ` [PATCH 21/26] mm/sparc64: " Peter Xu
2020-06-19 16:13 ` [PATCH 22/26] mm/unicore32: " Peter Xu
2020-06-19 16:13 ` [PATCH 23/26] mm/x86: " Peter Xu
2020-06-19 16:13 ` [PATCH 24/26] mm/xtensa: " Peter Xu
2020-06-19 16:14 ` [PATCH 25/26] mm: Clean up the last pieces of page fault accountings Peter Xu
2020-06-19 16:14 ` [PATCH 26/26] mm/gup: Remove task_struct pointer for all gup code Peter Xu
2020-06-26 22:31 [PATCH 00/26] mm: Page fault accounting cleanups Peter Xu
2020-06-26 22:31 ` [PATCH 01/26] mm: Do page fault accounting in handle_mm_fault Peter Xu
2020-06-29 1:52 ` John Hubbard
2020-06-29 14:56 ` Peter Xu
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