From: Jens Axboe <axboe@kernel.dk>
To: Christian Brauner <brauner@kernel.org>
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 10:33:03 -0700 [thread overview]
Message-ID: <f8227e1b-7d70-4868-bd89-c6029325d2ee@kernel.dk> (raw)
In-Reply-To: <20240109-gitarre-zettel-5c9b772561cf@brauner>
On 1/9/24 10:30 AM, Christian Brauner wrote:
> 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.
Yep, either revert or that patch fixes things for me.
--
Jens Axboe
prev parent reply other threads:[~2024-01-09 17:33 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
2024-01-09 17:33 ` Jens Axboe [this message]
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