From: Marcelo Tosatti <mtosatti@redhat.com>
To: Feng Tang <feng.tang@intel.com>
Cc: kernel test robot <rong.a.chen@intel.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Stephen Rothwell <sfr@canb.auug.org.au>,
lkp@01.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [LKP] [cpuidle] 259231a045: will-it-scale.per_process_ops -12.6% regression
Date: Fri, 3 Jan 2020 10:36:14 -0300 [thread overview]
Message-ID: <20200103133614.GA6604@fuller.cnet> (raw)
In-Reply-To: <20200103023117.GA1313@shbuild999.sh.intel.com>
Hi Feng,
On Fri, Jan 03, 2020 at 10:31:17AM +0800, Feng Tang wrote:
> On Tue, Dec 31, 2019 at 01:59:23PM +0800, Feng Tang wrote:
> > Hi Marcelo,
> >
> > On Wed, Sep 18, 2019 at 10:13:34AM +0800, kernel test robot wrote:
> > > Greeting,
> > >
> > > FYI, we noticed a -12.6% regression of will-it-scale.per_process_ops due to commit:
> > >
> > >
> > > commit: 259231a045616c4101d023a8f4dcc8379af265a6 ("cpuidle: add poll_limit_ns to cpuidle_device structure")
> > > https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git master
> >
> > Any comments on this? We re-run the test for 5.5-rc1, and the regression remains.
>
> Anyway, I found commit 259231a04 lost one "break" when moving
> the original code, thus the semantics is changed to the last
> enabled state's target_residency instead of the first enabled
> one's.
>
> I don't know if it's intentional, and I guess no, so here
> is a fix patch, please review, thanks
Not intentional.
> But even with this patch, the regression is still not recovered.
>
> - Feng
This has been fixed upstream already, should be on Rafael's GIT tree.
> >From cddd6b409e18ce97a8d7b851db4400396f71d857 Mon Sep 17 00:00:00 2001
> From: Feng Tang <feng.tang@intel.com>
> Date: Thu, 2 Jan 2020 16:58:31 +0800
> Subject: [PATCH] cpuidle: Add back the lost break in cpuidle_poll_time
>
> Commit c4cbb8b649b5 move the poll time calculation into a
> new function cpuidle_poll_time(), during which one "break"
> get lost, and the semantic is changed from the last enabled
> state's target_residency instead of the first enabled one's.
>
> So add it back.
>
> Fixes: c4cbb8b649b5 "cpuidle: add poll_limit_ns to cpuidle_device structure"
> Signed-off-by: Feng Tang <feng.tang@intel.com>
> Cc: Marcelo Tosatti <mtosatti@redhat.com>
> ---
> drivers/cpuidle/cpuidle.c | 1 +
> 1 file changed, 1 insertion(+)
About the regression... if you only revert the
drivers/cpuidle/poll_state.c
changes from
259231a045616c4101d023a8f4dcc8379af265a6
Is the performance regression gone?
next prev parent reply other threads:[~2020-01-06 12:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-18 2:13 [cpuidle] 259231a045: will-it-scale.per_process_ops -12.6% regression kernel test robot
2019-12-31 5:59 ` [LKP] " Feng Tang
2020-01-03 2:31 ` Feng Tang
2020-01-03 13:36 ` Marcelo Tosatti [this message]
2020-01-06 15:52 ` Feng Tang
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