linux-fsdevel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Tobin C. Harding" <me@tobin.cc>
To: Roman Gushchin <guro@fb.com>
Cc: "Tobin C. Harding" <tobin@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthew Wilcox <willy@infradead.org>,
	Alexander Viro <viro@ftp.linux.org.uk>,
	Christoph Hellwig <hch@infradead.org>,
	Pekka Enberg <penberg@cs.helsinki.fi>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Christopher Lameter <cl@linux.com>,
	Miklos Szeredi <mszeredi@redhat.com>,
	Andreas Dilger <adilger@dilger.ca>,
	Waiman Long <longman@redhat.com>, Tycho Andersen <tycho@tycho.ws>,
	Theodore Ts'o <tytso@mit.edu>, Andi Kleen <ak@linux.intel.com>,
	David Chinner <david@fromorbit.com>,
	Nick Piggin <npiggin@gmail.com>, Rik van Riel <riel@redhat.com>,
	Hugh Dickins <hughd@google.com>, Jonathan Corbet <corbet@lwn.net>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v5 13/16] slub: Enable balancing slabs across nodes
Date: Tue, 21 May 2019 11:44:57 +1000	[thread overview]
Message-ID: <20190521014457.GA27676@eros.localdomain> (raw)
In-Reply-To: <20190521010404.GB9552@tower.DHCP.thefacebook.com>

On Tue, May 21, 2019 at 01:04:10AM +0000, Roman Gushchin wrote:
> On Mon, May 20, 2019 at 03:40:14PM +1000, Tobin C. Harding wrote:
> > We have just implemented Slab Movable Objects (SMO).  On NUMA systems
> > slabs can become unbalanced i.e. many slabs on one node while other
> > nodes have few slabs.  Using SMO we can balance the slabs across all
> > the nodes.
> > 
> > The algorithm used is as follows:
> > 
> >  1. Move all objects to node 0 (this has the effect of defragmenting the
> >     cache).
> 
> This already sounds dangerous (or costly). Can't it be done without
> cross-node data moves?
>
> > 
> >  2. Calculate the desired number of slabs for each node (this is done
> >     using the approximation nr_slabs / nr_nodes).
> 
> So that on this step only (actual data size - desired data size) has
> to be moved?

This is just the most braindead algorithm I could come up with.  Surely
there are a bunch of things that could be improved.  Since I don't know
the exact use case it seemed best not to optimize for any one use case.

I'll review, comment on, and test any algorithm you come up with!

thanks,
Tobin.

  reply	other threads:[~2019-05-21  1:45 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-20  5:40 [RFC PATCH v5 00/16] Slab Movable Objects (SMO) Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 01/16] slub: Add isolate() and migrate() methods Tobin C. Harding
2019-05-21  0:37   ` Roman Gushchin
2019-05-20  5:40 ` [RFC PATCH v5 02/16] tools/vm/slabinfo: Add support for -C and -M options Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 03/16] slub: Sort slab cache list Tobin C. Harding
2019-05-21  0:38   ` Roman Gushchin
2019-05-20  5:40 ` [RFC PATCH v5 04/16] slub: Slab defrag core Tobin C. Harding
2019-05-21  0:51   ` Roman Gushchin
2019-05-21  1:15     ` Tobin C. Harding
2019-05-21  1:25       ` Roman Gushchin
2019-05-20  5:40 ` [RFC PATCH v5 05/16] tools/vm/slabinfo: Add remote node defrag ratio output Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 06/16] tools/vm/slabinfo: Add defrag_used_ratio output Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 07/16] tools/testing/slab: Add object migration test module Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 08/16] tools/testing/slab: Add object migration test suite Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 09/16] lib: Separate radix_tree_node and xa_node slab cache Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 10/16] xarray: Implement migration function for xa_node objects Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 11/16] tools/testing/slab: Add XArray movable objects tests Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 12/16] slub: Enable moving objects to/from specific nodes Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 13/16] slub: Enable balancing slabs across nodes Tobin C. Harding
2019-05-21  1:04   ` Roman Gushchin
2019-05-21  1:44     ` Tobin C. Harding [this message]
2019-05-20  5:40 ` [RFC PATCH v5 14/16] dcache: Provide a dentry constructor Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 15/16] dcache: Implement partial shrink via Slab Movable Objects Tobin C. Harding
2019-05-20  5:40 ` [RFC PATCH v5 16/16] dcache: Add CONFIG_DCACHE_SMO Tobin C. Harding
2019-05-21  0:57   ` Roman Gushchin
2019-05-21  1:31     ` Tobin C. Harding
2019-05-21  2:05       ` Roman Gushchin
2019-05-21  3:15         ` Tobin C. Harding
2019-05-29  3:54         ` Tobin C. Harding
2019-05-29 16:16           ` Roman Gushchin
2019-06-03  4:26             ` Tobin C. Harding
2019-06-03 20:34               ` Roman Gushchin

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=20190521014457.GA27676@eros.localdomain \
    --to=me@tobin.cc \
    --cc=adilger@dilger.ca \
    --cc=ak@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=cl@linux.com \
    --cc=corbet@lwn.net \
    --cc=david@fromorbit.com \
    --cc=guro@fb.com \
    --cc=hch@infradead.org \
    --cc=hughd@google.com \
    --cc=iamjoonsoo.kim@lge.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=longman@redhat.com \
    --cc=mszeredi@redhat.com \
    --cc=npiggin@gmail.com \
    --cc=penberg@cs.helsinki.fi \
    --cc=riel@redhat.com \
    --cc=rientjes@google.com \
    --cc=tobin@kernel.org \
    --cc=tycho@tycho.ws \
    --cc=tytso@mit.edu \
    --cc=viro@ftp.linux.org.uk \
    --cc=willy@infradead.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).