All of lore.kernel.org
 help / color / mirror / Atom feed
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH] sched: Fix numabalancing to work with isolated cpus
Date: Wed, 5 Apr 2017 07:20:06 +0530	[thread overview]
Message-ID: <20170405015006.GA4941@linux.vnet.ibm.com> (raw)
In-Reply-To: <20170404203714.c4mexerfq3ztanpm@techsingularity.net>

> > 
> > To avoid this, please check for isolated cpus before choosing a target
> > cpu.
> > 
> 
> Hmm, would this also prevent a task running inside a cgroup that is
> allowed accessed to isolated CPUs from balancing? I severely doubt it

Scheduler doesn't do any kind of load balancing for isolated cpus.

# grep -o "isolcpus=.*" /proc/cmdline 
isolcpus=56,64,72,80,88
# taskset -c "56,64,72,80" ebizzy -S 100 -t 44

(on another terminal)
# pgrep ebizzy
10437
# cat /proc/10437/status |grep Cpus_allowed_list
Cpus_allowed_list:      56,64,72,80
#

But the all the tasks would only run on cpu 56, even if its fully
overloaded.  Cpus 64,72,80 would be completely idle.  So on isolated
cpus, its the user who is in full control of scheduling the tasks on the
cpu.

> matters because if a process is isolated from interference then it
> follows that automatic NUMA balancing should not be involved. If

Yes, as an extension of the above, numa balancing should not be
involved.

> anything the protection should be absolute but either way;
> 
> Acked-by: Mel Gorman <mgorman@techsingularity.net>
> 

Thanks.

  reply	other threads:[~2017-04-05  1:50 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-04 17:27 Srikar Dronamraju
2017-04-04 18:56 ` Rik van Riel
2017-04-04 20:37 ` Mel Gorman
2017-04-05  1:50   ` Srikar Dronamraju [this message]
2017-04-05  8:09     ` Mel Gorman
2017-04-05 12:57 ` Michal Hocko
2017-04-05 15:22   ` Srikar Dronamraju
2017-04-05 16:44     ` Michal Hocko
2017-04-06  7:19       ` Srikar Dronamraju
2017-04-06  7:34         ` Michal Hocko
2017-04-06  9:23           ` Peter Zijlstra
2017-04-06 10:13             ` Michal Hocko
2017-04-06 10:29               ` Peter Zijlstra
2017-04-06 10:42                 ` Michal Hocko
2017-04-06 10:47                   ` Peter Zijlstra
2017-04-06 13:44                     ` Michal Hocko
2017-04-06  7:36 ` Mike Galbraith
2017-04-06  7:36 ` Peter Zijlstra

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=20170405015006.GA4941@linux.vnet.ibm.com \
    --to=srikar@linux.vnet.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mgorman@techsingularity.net \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    --cc=riel@redhat.com \
    --subject='Re: [PATCH] sched: Fix numabalancing to work with isolated cpus' \
    /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

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.