From: "Lu, Aaron" <aaron.lu@intel.com>
To: "bcodding@redhat.com" <bcodding@redhat.com>,
"jlayton@redhat.com" <jlayton@redhat.com>
Cc: "torvalds@linux-foundation.org" <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"lkp@01.org" <lkp@01.org>, "Ye, Xiaolong" <xiaolong.ye@intel.com>
Subject: Re: [LKP] [lkp-robot] [fs/locks] 52306e882f: stress-ng.lockofd.ops_per_sec -11% regression
Date: Wed, 6 Dec 2017 01:43:52 +0000 [thread overview]
Message-ID: <1512524641.18934.2.camel@intel.com> (raw)
In-Reply-To: <1512471662.4125.2.camel@redhat.com>
On Tue, 2017-12-05 at 06:01 -0500, Jeff Layton wrote:
> On Tue, 2017-12-05 at 13:57 +0800, Aaron Lu wrote:
> > On Wed, Nov 08, 2017 at 03:22:33PM +0800, Aaron Lu wrote:
> > > On Thu, Sep 28, 2017 at 04:02:23PM +0800, kernel test robot wrote:
> > > >
> > > > Greeting,
> > > >
> > > > FYI, we noticed a -11% regression of stress-ng.lockofd.ops_per_sec due to commit:
> > > >
> > > >
> > > > commit: 52306e882f77d3fd73f91435c41373d634acc5d2 ("fs/locks: Use allocation rather than the stack in fcntl_getlk()")
> > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > >
> > > It's been a while, I wonder what do you think of this regression?
> > >
> > > The test stresses byte-range locks AFAICS and since the commit uses
> > > dynamic allocation instead of stack for the 'struct file_lock', it sounds
> > > natural the performance regressed for this test.
> > >
> > > Now the question is, do we care about the performance regression here?
> >
> > Appreciated it if you can share your opinion on this, thanks.
> >
> > Regards,
> > Aaron
> >
>
> Sorry I missed your earlier mail about this. My feeling is to not worry
Never mind :)
> about it. struct file_lock is rather large, so putting it on the stack
> was always a bit dangerous, and F_GETLK is a rather uncommon operation
> anyway.
>
> That said, if there are real-world workloads that have regressed because
> of this patch, I'm definitely open to backing it out.
>
> Does anyone else have opinions on the matter?
Your comments makes sense to me, thanks for the reply.
prev parent reply other threads:[~2017-12-06 1:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-28 8:02 [lkp-robot] [fs/locks] 52306e882f: stress-ng.lockofd.ops_per_sec -11% regression kernel test robot
2017-11-08 7:22 ` [LKP] " Aaron Lu
2017-12-05 5:57 ` Aaron Lu
2017-12-05 11:01 ` Jeff Layton
2017-12-06 1:43 ` Lu, Aaron [this message]
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