From: Kees Cook <keescook@chromium.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, ccross@google.com,
sumit.semwal@linaro.org, mhocko@suse.com, dave.hansen@intel.com,
willy@infradead.org, kirill.shutemov@linux.intel.com,
vbabka@suse.cz, hannes@cmpxchg.org, corbet@lwn.net,
viro@zeniv.linux.org.uk, rdunlap@infradead.org,
kaleshsingh@google.com, peterx@redhat.com, rppt@kernel.org,
peterz@infradead.org, catalin.marinas@arm.com,
vincenzo.frascino@arm.com, chinwen.chang@mediatek.com,
axelrasmussen@google.com, aarcange@redhat.com, jannh@google.com,
apopple@nvidia.com, jhubbard@nvidia.com, yuzhao@google.com,
will@kernel.org, fenghua.yu@intel.com,
thunder.leizhen@huawei.com, hughd@google.com,
feng.tang@intel.com, jgg@ziepe.ca, guro@fb.com,
tglx@linutronix.de, krisman@collabora.com,
chris.hyser@oracle.com, pcc@google.com, ebiederm@xmission.com,
axboe@kernel.dk, legion@kernel.org, eb@emlix.com,
songmuchun@bytedance.com, viresh.kumar@linaro.org,
thomascedeno@google.com, sashal@kernel.org, cxfcosmos@gmail.com,
linux@rasmusvillemoes.dk, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, kernel-team@android.com
Subject: Re: [PATCH v8 3/3] mm: add anonymous vma name refcounting
Date: Fri, 27 Aug 2021 22:28:41 -0700 [thread overview]
Message-ID: <202108271746.F444DA6C9@keescook> (raw)
In-Reply-To: <20210827191858.2037087-4-surenb@google.com>
On Fri, Aug 27, 2021 at 12:18:58PM -0700, Suren Baghdasaryan wrote:
> While forking a process with high number (64K) of named anonymous vmas the
> overhead caused by strdup() is noticeable. Experiments with ARM64 Android
> device show up to 40% performance regression when forking a process with
> 64k unpopulated anonymous vmas using the max name lengths vs the same
> process with the same number of anonymous vmas having no name.
> Introduce anon_vma_name refcounted structure to avoid the overhead of
> copying vma names during fork() and when splitting named anonymous vmas.
> When a vma is duplicated, instead of copying the name we increment the
> refcount of this structure. Multiple vmas can point to the same
> anon_vma_name as long as they increment the refcount. The name member of
> anon_vma_name structure is assigned at structure allocation time and is
> never changed. If vma name changes then the refcount of the original
> structure is dropped, a new anon_vma_name structure is allocated
> to hold the new name and the vma pointer is updated to point to the new
> structure.
> With this approach the fork() performance regressions is reduced 3-4x
> times and with usecases using more reasonable number of VMAs (a few
> thousand) the regressions is not measurable.
I like the refcounting; thank you!
Since patch2 adds a lot of things that are changed by patch3; maybe
combine them?
--
Kees Cook
next prev parent reply other threads:[~2021-08-28 5:28 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-27 19:18 [PATCH v8 0/3] Anonymous VMA naming patches Suren Baghdasaryan
2021-08-27 19:18 ` [PATCH v8 1/3] mm: rearrange madvise code to allow for reuse Suren Baghdasaryan
2021-08-28 0:14 ` Kees Cook
2021-08-28 0:58 ` Suren Baghdasaryan
2021-08-28 16:19 ` Cyrill Gorcunov
2021-08-28 21:59 ` Suren Baghdasaryan
2021-08-27 19:18 ` [PATCH v8 2/3] mm: add a field to store names for private anonymous memory Suren Baghdasaryan
2021-08-28 1:47 ` Matthew Wilcox
2021-08-28 5:52 ` Kees Cook
2021-08-28 21:47 ` Suren Baghdasaryan
2021-08-30 8:12 ` Rasmus Villemoes
2021-08-30 16:16 ` Suren Baghdasaryan
2021-08-30 16:59 ` Matthew Wilcox
2021-08-31 17:21 ` Suren Baghdasaryan
2021-08-28 21:28 ` Cyrill Gorcunov
2021-08-28 21:53 ` Suren Baghdasaryan
2021-09-01 8:09 ` Michal Hocko
2021-09-01 15:28 ` Suren Baghdasaryan
2021-09-01 8:10 ` Michal Hocko
2021-09-01 15:42 ` Suren Baghdasaryan
2021-09-03 11:49 ` Michal Hocko
2021-09-03 15:47 ` Suren Baghdasaryan
2021-08-27 19:18 ` [PATCH v8 3/3] mm: add anonymous vma name refcounting Suren Baghdasaryan
2021-08-28 5:28 ` Kees Cook [this message]
2021-08-28 21:13 ` Suren Baghdasaryan
2021-08-30 7:03 ` Rolf Eike Beer
2021-08-30 16:12 ` Suren Baghdasaryan
2021-08-28 12:48 ` [PATCH v8 0/3] Anonymous VMA naming patches Pavel Machek
2021-08-28 22:06 ` Suren Baghdasaryan
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