linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@kernel.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Roman Gushchin <guro@fb.com>, Chris Down <chris@chrisdown.name>,
	Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH 0/3] mm: improve proportional memcg protection
Date: Tue, 28 Apr 2020 12:43:00 +0200	[thread overview]
Message-ID: <20200428104300.GN28637@dhcp22.suse.cz> (raw)
In-Reply-To: <CALOAHbCjxfhGVWWGugKa91Et-Ate6KYuO4GewTZFPdN8gsCVkg@mail.gmail.com>

On Tue 28-04-20 16:22:46, Yafang Shao wrote:
> On Tue, Apr 28, 2020 at 4:05 PM Michal Hocko <mhocko@kernel.org> wrote:
> >
> > On Tue 28-04-20 09:45:27, Yafang Shao wrote:
> > [...]
> > > Seems we can't get an agreement on how to improve current code.
> > > So I will submit a patch to revert the commit 9783aa9917f8 ("mm,
> > > memcg: proportional memory.{low,min} reclaim") first.
> >
> > My current understanding is that the issue we are discussing here is
> > mostly theoretical. Your changelog doesn't really talk about any real
> > life workloads that would be suffering.
> 
> Is real life workload really important ?

It is really important to make cost vs. benefit decisions. Like whether
to rever the said commit or not.

> If so, why an issue[1] occured in the real workload report by me in
> 2019 that memcg proection can't protect inactive pages (inodes) is
> ignored again and again ?

I do not think it is ignored. IIRC there was not an agreement on the way
to fix this. I could get involved very much because there were other
higher priority things to take care. People are simply busy.

> So I'm questioning that what is the real life workload ?

It is a workload which does something useful for their users.
[...]
> > So it would be really more helpful to not insist on unrelated
> > implementation details and focus on two things 1) split up the effective
> > values calculation from the predicate (cleanup without any functional
> > changes) 2) make the calculation more robust against racing reclaimers.
> >
> 
> Another thing should be considered as well, 0) don't access
> memroy.emin and elow in get_scan_count().

If you can achieve the gradual transition over protections by other
means then I am really interested in more details.
-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2020-04-28 10:43 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-25 15:24 [PATCH 0/3] mm: improve proportional memcg protection Yafang Shao
2020-04-25 15:24 ` [PATCH 1/3] mm: move struct scan_control into internal.h Yafang Shao
2020-04-25 15:24 ` [PATCH 2/3] mm: add reclaim context as a new parameter in mem_cgroup_protected() Yafang Shao
2020-04-25 15:24 ` [PATCH 3/3] mm: improvements on memcg protection functions Yafang Shao
2020-04-27  9:40   ` Michal Hocko
2020-04-27 10:09     ` Yafang Shao
2020-04-27 10:50       ` Michal Hocko
2020-04-27 11:06         ` Yafang Shao
2020-04-27 11:24           ` Michal Hocko
2020-04-27 11:32             ` Yafang Shao
2020-04-27 17:05 ` [PATCH 0/3] mm: improve proportional memcg protection Johannes Weiner
2020-04-28  1:45   ` Yafang Shao
2020-04-28  3:37     ` Johannes Weiner
2020-04-28  6:00       ` Yafang Shao
2020-04-28  8:05     ` Michal Hocko
2020-04-28  8:22       ` Yafang Shao
2020-04-28 10:43         ` Michal Hocko [this message]
2020-04-28 12:25           ` Yafang Shao
2020-04-28 12:42             ` Michal Hocko

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200428104300.GN28637@dhcp22.suse.cz \
    --to=mhocko@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=chris@chrisdown.name \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=laoar.shao@gmail.com \
    --cc=linux-mm@kvack.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).