LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Paul Jackson <pj@sgi.com>
To: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: kosaki.motohiro@jp.fujitsu.com, andi@firstfloor.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	akpm@linux-foundation.org, clameter@sgi.com, rientjes@google.com,
	mel@csn.ul.ie
Subject: Re: [2.6.24-rc8-mm1][regression?] numactl --interleave=all doesn't works on memoryless node.
Date: Tue, 5 Feb 2008 04:17:55 -0600	[thread overview]
Message-ID: <20080205041755.3411b5cc.pj@sgi.com> (raw)
In-Reply-To: <1202149243.5028.61.camel@localhost>

Lee wrote:
> I don't know the current state of Paul's rework of cpusets and
> mems_allowed.  That probably resolves this issue, if he still plans on
> allowing a fully populated mask to indicate interleaving over all
> allowed nodes.

It got a bit stalled out for the last month (my employer had other
designs on my time.)  But I'd really like to drive it home.

What happened so far, in December 2007 and earlier, is that a few of us:

  David Rientjes <rientjes@google.com>
  Lee.Schermerhorn@hp.com
  Christoph Lameter <clameter@sgi.com>
  Andi Kleen <ak@suse.de>

had a discussion, motivated in good part by the need to allow a
mempolicy of MPOL_INTERLEAVE over all nodes currently available in
the cpuset, where that interleave policy was robustly preserved if
the cpuset changed (without requiring the application to somehow
"know" its cpuset had changed and reissuing the set_mempolicy call.)

But that discussion touched on some other long standing deficiencies
in the way that I had originally glued cpusets and memory policies
together.  The current mechanism doesn't handle changing cpusets very
well, especially if the number of nodes in the cpuset increases.

Obviously, I can't change the current behaviour, especially of the
mempolicy system calls.  I can only add new options that provide new
alternatives.

The patchset I'd like to drive home addresses these issues with a
couple of additional MPOL_* flags, upward compatible, that alter the
way that nodemasks are mapped into cpusets, and remapped if the cpuset
subsequently changes.

The next two steps I need to take are:
 1) propose this patch, with careful explanation (it's easy to lose
    one's bearings in the mappings and remappings of node numberings)
    to a wider audience, such as linux-mm or linux-kernel, and
 2) carefully test this, especially on each code path I touched in
    mm/mempolicy.c, where the changes were delicate, to ensure I
    didn't break any existing code.

There were also some other, smaller patches proposed, by myself and
others.  I was preferring to address a wider set of the long standing
issues in this area, but the others above mostly preferred the smaller
patches.  This needs to be discussed in a wider forum, and a concensus
reached.

Hopefully this week or next, I will publish this patch proposal.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214

  parent reply	other threads:[~2008-02-05 10:18 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-02  8:12 KOSAKI Motohiro
2008-02-02  9:09 ` Andi Kleen
2008-02-02  9:37   ` KOSAKI Motohiro
2008-02-02 11:30     ` Andi Kleen
2008-02-04 19:03       ` Christoph Lameter
2008-02-04 18:20     ` Lee Schermerhorn
2008-02-05  9:26       ` [2.6.24 regression][BUGFIX] " KOSAKI Motohiro
2008-02-05 21:57         ` Lee Schermerhorn
2008-02-05 22:12           ` Christoph Lameter
2008-02-06 16:00             ` Lee Schermerhorn
2008-02-05 22:15           ` Paul Jackson
2008-02-06  2:17           ` David Rientjes
2008-02-06 16:11             ` Lee Schermerhorn
2008-02-06  6:49           ` KOSAKI Motohiro
2008-02-06 17:38         ` Lee Schermerhorn
2008-02-07  8:31           ` KOSAKI Motohiro
2008-02-08 19:45         ` [PATCH 2.6.24-mm1] Mempolicy: silently restrict nodemask to allowed nodes V3 Lee Schermerhorn
2008-02-09 18:11           ` KOSAKI Motohiro
2008-02-10  5:29           ` KOSAKI Motohiro
2008-02-10  5:49             ` Greg KH
2008-02-10  7:42               ` Linus Torvalds
2008-02-10 10:31                 ` Andrew Morton
2008-02-11 16:47                 ` Lee Schermerhorn
2008-02-12  4:30                   ` [PATCH for 2.6.24][regression fix] " KOSAKI Motohiro
2008-02-12  5:06                     ` David Rientjes
2008-02-12  5:07                     ` Andrew Morton
2008-02-12 13:18                       ` KOSAKI Motohiro
2008-02-05 10:17       ` Paul Jackson [this message]
2008-02-05 11:14         ` [2.6.24-rc8-mm1][regression?] numactl --interleave=all doesn't works on memoryless node KOSAKI Motohiro
2008-02-05 19:56         ` David Rientjes
2008-02-05 20:51           ` Paul Jackson
2008-02-05 21:03             ` David Rientjes
2008-02-05 21:33               ` Paul Jackson
2008-02-05 22:04                 ` Lee Schermerhorn
2008-02-05 22:44                   ` David Rientjes
2008-02-05 22:50                   ` Paul Jackson
2008-02-05 14:31       ` Mel Gorman
2008-02-05 15:23         ` Lee Schermerhorn
2008-02-05 18:12           ` Christoph Lameter
2008-02-05 18:27             ` Lee Schermerhorn
2008-02-05 19:04               ` Christoph Lameter
2008-02-05 19:15                 ` Paul Jackson
2008-02-05 20:06                   ` David Rientjes

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=20080205041755.3411b5cc.pj@sgi.com \
    --to=pj@sgi.com \
    --cc=Lee.Schermerhorn@hp.com \
    --cc=akpm@linux-foundation.org \
    --cc=andi@firstfloor.org \
    --cc=clameter@sgi.com \
    --cc=kosaki.motohiro@jp.fujitsu.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mel@csn.ul.ie \
    --cc=rientjes@google.com \
    --subject='Re: [2.6.24-rc8-mm1][regression?] numactl --interleave=all doesn'\''t works on memoryless node.' \
    /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 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).