From: Michal Hocko <mhocko@kernel.org>
To: Minchan Kim <minchan@kernel.org>
Cc: kernel test robot <oliver.sang@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Miguel de Dios <migueldedios@google.com>,
Wei Wang <wvw@google.com>, Johannes Weiner <hannes@cmpxchg.org>,
Mel Gorman <mgorman@techsingularity.net>,
lkp@01.org
Subject: Re: [mm] 755d6edc1a: will-it-scale.per_process_ops -4.1% regression
Date: Tue, 6 Aug 2019 13:11:09 +0200 [thread overview]
Message-ID: <20190806111109.GV11812@dhcp22.suse.cz> (raw)
In-Reply-To: <20190806110024.GA32615@google.com>
On Tue 06-08-19 20:00:24, Minchan Kim wrote:
> On Tue, Aug 06, 2019 at 10:04:15AM +0200, Michal Hocko wrote:
> > On Tue 06-08-19 15:05:47, kernel test robot wrote:
> > > Greeting,
> > >
> > > FYI, we noticed a -4.1% regression of will-it-scale.per_process_ops due to commit:
> >
> > I have to confess I cannot make much sense from numbers because they
> > seem to be too volatile and the main contributor doesn't stand up for
> > me. Anyway, regressions on microbenchmarks like this are not all that
> > surprising when a locking is slightly changed and the critical section
> > made shorter. I have seen that in the past already.
>
> I guess if it's multi process workload. The patch will give more chance
> to be scheduled out so TLB miss ratio would be bigger than old.
> I see it's natural trade-off for latency vs. performance so only thing
> I could think is just increase threshold from 32 to 64 or 128?
This still feels like a magic number tunning, doesn't it?
--
Michal Hocko
SUSE Labs
prev parent reply other threads:[~2019-08-06 11:11 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-29 7:10 [PATCH] mm: release the spinlock on zap_pte_range Minchan Kim
2019-07-29 7:45 ` Michal Hocko
2019-07-29 8:20 ` Minchan Kim
2019-07-29 8:35 ` Michal Hocko
2019-07-30 12:11 ` Minchan Kim
2019-07-30 12:32 ` Michal Hocko
2019-07-30 12:39 ` Minchan Kim
2019-07-30 12:57 ` Michal Hocko
2019-07-31 5:44 ` Minchan Kim
2019-07-31 7:21 ` Michal Hocko
2019-08-06 10:55 ` Minchan Kim
2019-08-09 12:43 ` [RFC PATCH] mm: drop mark_page_access from the unmap path Michal Hocko
2019-08-09 17:57 ` Mel Gorman
2019-08-09 18:34 ` Johannes Weiner
2019-08-12 8:09 ` Michal Hocko
2019-08-12 15:07 ` Johannes Weiner
2019-08-13 10:51 ` Michal Hocko
2019-08-26 12:06 ` Michal Hocko
2019-08-27 16:00 ` Johannes Weiner
2019-08-27 18:41 ` Michal Hocko
2019-07-30 19:42 ` [PATCH] mm: release the spinlock on zap_pte_range Andrew Morton
2019-07-31 6:14 ` Minchan Kim
2019-08-06 7:05 ` [mm] 755d6edc1a: will-it-scale.per_process_ops -4.1% regression kernel test robot
[not found] ` <20190806080415.GG11812@dhcp22.suse.cz>
2019-08-06 11:00 ` Minchan Kim
2019-08-06 11:11 ` Michal Hocko [this message]
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