From: Christian Brauner <brauner@kernel.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Amir Goldstein <amir73il@gmail.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH] Revert "fsnotify: optionally pass access range in file permission hooks"
Date: Tue, 9 Jan 2024 18:30:07 +0100 [thread overview]
Message-ID: <20240109-gitarre-zettel-5c9b772561cf@brauner> (raw)
In-Reply-To: <53682ece-f0e7-48de-9a1c-879ee34b0449@kernel.dk>
On Tue, Jan 09, 2024 at 09:08:40AM -0700, Jens Axboe wrote:
> This reverts commit d9e5d31084b024734e64307521414ef0ae1d5333.
>
> This commit added an extra fsnotify call from rw_verify_area(), which
> can be a very hot path. In my testing, this adds roughly 5-6% extra
> overhead per IO, which is quite a lot. As a result, throughput of
> said test also drops by 5-6%, as it is CPU bound. Looking at perf,
> it's apparent why:
>
> 3.36% [kernel.vmlinux] [k] fsnotify
> 2.32% [kernel.vmlinux] [k] __fsnotify_paren
>
> which directly correlates with performance lost.
>
> As the rationale for this patch isn't very strong, revert this commit
> for now and reclaim the performance.
>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>
> ---
Thanks for tracking this down! I think Amir, you, and I came to the
conclusion that we can fix this in without having to revert. Amir is
sending out a new patch later tonight. I'll get that fixed by the end of
the week.
Christian
next prev parent reply other threads:[~2024-01-09 17:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-09 16:08 [PATCH] Revert "fsnotify: optionally pass access range in file permission hooks" Jens Axboe
2024-01-09 17:30 ` Christian Brauner [this message]
2024-01-09 17:33 ` Jens Axboe
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