linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@suse.com>
To: yong w <yongw.pur@gmail.com>
Cc: Tejun Heo <tj@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.com>,
	alexs@kernel.org, Wei Yang <richard.weiyang@gmail.com>,
	Hui Su <sh_def@163.com>, Stephen Rothwell <sfr@canb.auug.org.au>,
	wang.yong12@zte.com.cn, Cgroups <cgroups@vger.kernel.org>,
	linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>,
	yang.yang29@zte.com.cn
Subject: Re: [PATCH v2] mm: Add configuration to control whether vmpressure notifier is enabled
Date: Mon, 30 Aug 2021 15:49:19 +0200	[thread overview]
Message-ID: <YSzh31BasoxUQXAu@dhcp22.suse.cz> (raw)
In-Reply-To: <CAOH5QeDUUqrMnuws6cnBDU_oub4cK6KsHeX39p7Eikr4Bcjcnw@mail.gmail.com>

On Sun 22-08-21 17:46:08, yong w wrote:
> > All those reasons should be a part of the changelog.
> >....
> > I am not sure these are sufficient justifications but that is something
> > to discuss. And hence it should be a part of the changelog.
> >
> OK, These reasons will be added to the patch notesin later versions.
> 
> > > 3. In the case where the user does not need vmpressure,  vmpressure
> > > calculation is additional overhead.
> >
> > You should quantify that and argue why that overhead cannot be further
> > reduced without config/boot time knobs.
> >
> The test results of the previously used PFT tool may not be obvious.
> Is there a better way to quantify it?

This is a question for you to answer I am afraid. You want to add a
configuration option and (as explained) that is not free of cost from
the maintenance POV. There must a very good reason to do that.

> > > In some special scenes with tight memory, vmpressure will be executed
> > > frequently.we use "likely" and "inline"
> > > to improve the performance of the kernel, why not reduce some
> > > unnecessary calculations?
> >
> > I am all for improving the code. Is it possible to do it by other means?
> > E.g. reduce a potential overhead when there no events registered?
> Yes, the method you mentioned may be feasible, but it does not conflict
> with this patch.

It is not in conflict but runtime overhead reduction without more burden
on the configurability is usually a preferred approach.
-- 
Michal Hocko
SUSE Labs

  reply	other threads:[~2021-08-30 13:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-19 23:53 [PATCH v2] mm: Add configuration to control whether vmpressure notifier is enabled yongw.pur
2021-08-20 11:26 ` Michal Hocko
2021-08-20 15:20   ` yong w
2021-08-20 15:41     ` Michal Hocko
2021-08-22  9:46       ` yong w
2021-08-30 13:49         ` Michal Hocko [this message]
2021-09-04 10:41           ` yong w
2021-09-06  6:37             ` Michal Hocko
2021-08-20 11:42 ` Shakeel Butt
2021-08-20 14:29   ` yong w
2021-08-22 10:06     ` yong w

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=YSzh31BasoxUQXAu@dhcp22.suse.cz \
    --to=mhocko@suse.com \
    --cc=akpm@linux-foundation.org \
    --cc=alexs@kernel.org \
    --cc=cgroups@vger.kernel.org \
    --cc=corbet@lwn.net \
    --cc=guro@fb.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=peterz@infradead.org \
    --cc=richard.weiyang@gmail.com \
    --cc=sfr@canb.auug.org.au \
    --cc=sh_def@163.com \
    --cc=shakeelb@google.com \
    --cc=tglx@linutronix.de \
    --cc=tj@kernel.org \
    --cc=vdavydov.dev@gmail.com \
    --cc=wang.yong12@zte.com.cn \
    --cc=yang.yang29@zte.com.cn \
    --cc=yongw.pur@gmail.com \
    /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).