From: Michal Hocko <mhocko@kernel.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Rik van Riel <riel@redhat.com>, Shaohua Li <shli@kernel.org>,
Hugh Dickins <hughd@google.com>,
Fengguang Wu <fengguang.wu@intel.com>,
Tim Chen <tim.c.chen@intel.com>,
Dave Hansen <dave.hansen@intel.com>
Subject: Re: [PATCH] mm, swap: Make VMA based swap readahead configurable
Date: Mon, 2 Oct 2017 09:23:45 +0200 [thread overview]
Message-ID: <20171002072345.sd5zcbk4y34hh3mk@dhcp22.suse.cz> (raw)
In-Reply-To: <87mv5f8wkj.fsf@yhuang-dev.intel.com>
On Thu 28-09-17 09:02:20, Huang, Ying wrote:
> Hi, Michal,
>
> Michal Hocko <mhocko@kernel.org> writes:
>
> > On Wed 27-09-17 23:10:08, Minchan Kim wrote:
> >> On Wed, Sep 27, 2017 at 03:50:34PM +0200, Michal Hocko wrote:
> >> > On Wed 27-09-17 22:41:17, Minchan Kim wrote:
> >> > > On Wed, Sep 27, 2017 at 03:22:41PM +0200, Michal Hocko wrote:
> >> > [...]
> >> > > > simply cannot disable swap readahead when page-cluster is 0?
> >> > >
> >> > > That's was what I want really but Huang want to use two readahead
> >> > > algorithms in parallel so he wanted to keep two separated disable
> >> > > knobs.
> >> >
> >> > If it breaks existing and documented behavior then it is a clear
> >> > regression and it should be fixed. I do not see why this should be
> >> > disputable at all.
> >>
> >> Indeed but Huang doesn't think so. He has thought it's not a regression.
> >> Frankly speaking, I'm really bored of discussing with it.
> >> https://marc.info/?l=linux-mm&m=150526413319763&w=2
> >
> > Then send a patch explaining why you consider this a regression with
> > some numbers backing it and I will happily ack it.
>
> I still think there may be a performance regression for some users
> because of the change of the algorithm and the knobs, and the
> performance regression can be resolved via setting the new knob. But I
> don't think there will be a functionality regression. Do you agree?
I am not sure I understand. One thing is clear though. Your change has
introduced a regression as described by Minchan. And that has to be
resolved no matter what. You cannot expect users will tweak the system
to resolve it or configure their systems in a specific way.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-10-02 7:23 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-21 1:33 Huang, Ying
2017-09-25 5:41 ` Minchan Kim
2017-09-25 5:54 ` Huang, Ying
2017-09-25 6:17 ` Minchan Kim
2017-09-25 6:24 ` Huang, Ying
2017-09-25 6:30 ` Minchan Kim
2017-09-26 13:21 ` Michal Hocko
2017-09-27 1:36 ` Huang, Ying
2017-09-27 5:04 ` Minchan Kim
2017-09-27 7:48 ` Michal Hocko
2017-09-27 8:04 ` Minchan Kim
2017-09-27 8:35 ` Michal Hocko
2017-09-27 13:15 ` Minchan Kim
2017-09-27 13:22 ` Michal Hocko
2017-09-27 13:41 ` Minchan Kim
2017-09-27 13:50 ` Michal Hocko
2017-09-27 14:10 ` Minchan Kim
2017-09-27 14:17 ` Michal Hocko
2017-09-28 1:02 ` Huang, Ying
2017-10-02 7:23 ` Michal Hocko [this message]
2017-10-02 15:45 ` Dave Hansen
2017-10-02 21:49 ` Andrew Morton
2017-10-06 12:28 ` huang ying
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