From: Andrew Morton <akpm@linux-foundation.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: liam@infradead.org, ljs@kernel.org, vbabka@kernel.org,
david@kernel.org, willy@infradead.org, jannh@google.com,
paulmck@kernel.org, pfalcato@suse.de, xueyuan.chen21@gmail.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v4 0/7] read proc/pid/smaps_rollup under per-vma lock
Date: Sat, 12 Sep 2026 00:24:36 -0700 [thread overview]
Message-ID: <20260912002436.0605a85b912eb8ae406cecf0@linux-foundation.org> (raw)
In-Reply-To: <20260911194145.1781926-1-surenb@google.com>
On Fri, 11 Sep 2026 12:41:38 -0700 Suren Baghdasaryan <surenb@google.com> wrote:
> proc/pid/smaps_rollup can be read using the combination of RCU and
> VMA read locks, similar to proc/pid/{maps|smaps|numa_maps}. RCU is
> required to safely traverse the VMA tree and VMA lock stabilizes the
> VMA being processed and the pagetable walk.
> Note that we have to keep the logic to drop mmap_lock on contention
> because even when using per-VMA locks we might have to fall back to
> holding the mmap_lock.
Nice. Queued, thanks.
The speedups described in [6/7] are significant, although I don't know
how representative Paul's tests are. Probably not very.
So I don't know how much improvement our users will be seeing from
these changes?
And I don't know how much usage smaps_rollup gets in the real world?
As I've no doubt you know, Sashiko is saying things. About these
patches and about the current code. Its pre-existing
clear_soft_dirty_pmd() driveby find looks significant.
https://sashiko.dev/#/patchset/20260911194145.1781926-1-surenb@google.com
next prev parent reply other threads:[~2026-09-12 7:24 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-11 19:41 [PATCH v4 0/7] read proc/pid/smaps_rollup under per-vma lock Suren Baghdasaryan
2026-09-11 19:41 ` [PATCH v4 1/7] proc/task_mmu: remove unnecessary helpers Suren Baghdasaryan
2026-09-11 19:41 ` [PATCH v4 2/7] proc/task_mmu: remove unnecessary inlines in function definitions Suren Baghdasaryan
2026-09-11 19:41 ` [PATCH v4 3/7] proc/task_mmu: clarify shmem mapping walk conditions in smap_gather_stats() Suren Baghdasaryan
2026-09-11 19:44 ` Lorenzo Stoakes (ARM)
2026-09-11 21:00 ` David Hildenbrand (Arm)
2026-09-11 21:31 ` Suren Baghdasaryan
2026-09-11 19:41 ` [PATCH v4 4/7] proc/task_mmu: remove special-casing of smap_gather_stats() start parameter Suren Baghdasaryan
2026-09-11 19:45 ` Lorenzo Stoakes (ARM)
2026-09-11 19:47 ` Suren Baghdasaryan
2026-09-11 19:41 ` [PATCH v4 5/7] proc/task_mmu: change proc_get_vma() to stop returning gate VMA at the end Suren Baghdasaryan
2026-09-11 19:41 ` [PATCH v4 6/7] proc/task_mmu: read proc/pid/smaps_rollup under per-vma lock Suren Baghdasaryan
2026-09-11 19:41 ` [PATCH v4 7/7] selftests/proc: add /proc/pid/smaps_rollup tearing tests Suren Baghdasaryan
2026-09-12 7:24 ` Andrew Morton [this message]
2026-09-12 18:55 ` [PATCH v4 0/7] read proc/pid/smaps_rollup under per-vma lock Paul E. McKenney
2026-09-13 19:26 ` Suren Baghdasaryan
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