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From: Fox Chen <foxhlchen@gmail.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ian Kent <raven@themaw.net>
Cc: Tejun Heo <tj@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
	Eric Sandeen <sandeen@sandeen.net>,
	Brice Goglin <brice.goglin@gmail.com>,
	Rick Lindsley <ricklind@linux.vnet.ibm.com>,
	David Howells <dhowells@redhat.com>,
	Miklos Szeredi <miklos@szeredi.hu>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 0/5] kernfs: proposed locking and concurrency improvement
Date: Wed, 12 May 2021 16:54:07 +0800	[thread overview]
Message-ID: <CAC2o3DJdwr0aqT6LwhuRj8kyXt6NAPex2nG5ToadUTJ3Jqr_4w@mail.gmail.com> (raw)
In-Reply-To: <CAC2o3DJm0ugq60c8mBafjd81nPmhpBKBT5cCKWvc4rYT0dDgGg@mail.gmail.com>

On Wed, May 12, 2021 at 4:47 PM Fox Chen <foxhlchen@gmail.com> wrote:
>
> Hi,
>
> I ran it on my benchmark (https://github.com/foxhlchen/sysfs_benchmark).
>
> machine: aws c5 (Intel Xeon with 96 logical cores)
> kernel: v5.12
> benchmark: create 96 threads and bind them to each core then run
> open+read+close on a sysfs file simultaneously for 1000 times.
> result:
> Without the patchset, an open+read+close operation takes 550-570 us,
> perf shows significant time(>40%) spending on mutex_lock.
> After applying it, it takes 410-440 us for that operation and perf
> shows only ~4% time on mutex_lock.
>
> It's weird, I don't see a huge performance boost compared to v2, even

I meant I don't see a huge performance boost here and it's way worse than v2.
IIRC, for v2 fastest one only takes 40us


> though there is no mutex problem from the perf report.
> I've put console outputs and perf reports on the attachment for your reference.
>
>
> thanks,
> fox

fox

  reply	other threads:[~2021-05-12  8:54 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-12  0:38 [PATCH v4 0/5] kernfs: proposed locking and concurrency improvement Ian Kent
2021-05-12  0:38 ` [PATCH v4 1/5] kernfs: move revalidate to be near lookup Ian Kent
2021-05-12  0:38 ` [PATCH v4 2/5] kernfs: use VFS negative dentry caching Ian Kent
2021-05-12  0:39 ` [PATCH v4 3/5] kernfs: switch kernfs to use an rwsem Ian Kent
2021-05-12  0:39 ` [PATCH v4 4/5] kernfs: use i_lock to protect concurrent inode updates Ian Kent
2021-05-12  0:39 ` [PATCH v4 5/5] kernfs: add kernfs_need_inode_refresh() Ian Kent
2021-05-12  6:21 ` [PATCH v4 0/5] kernfs: proposed locking and concurrency improvement Greg Kroah-Hartman
2021-05-12  7:16   ` Fox Chen
2021-05-12  8:47     ` Fox Chen
2021-05-12  8:54       ` Fox Chen [this message]
2021-05-13 14:10         ` Ian Kent
2021-05-13 15:37           ` Fox Chen
2021-05-14  1:34             ` Ian Kent
2021-05-14  2:34               ` Fox Chen
2021-05-17  1:32                 ` Ian Kent
2021-05-18  8:26                   ` Fox Chen
2021-05-27  1:23                   ` Ian Kent
2021-05-27  6:50                     ` Greg Kroah-Hartman
2021-05-28  5:45                       ` Ian Kent
2021-05-13 13:50   ` Ian Kent
2021-05-13 15:19     ` Greg Kroah-Hartman
2021-05-14  1:02       ` Ian Kent

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