LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Christopher Lameter <cl@linux.com>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Mike Snitzer <snitzer@redhat.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Matthew Wilcox <willy@infradead.org>,
	Pekka Enberg <penberg@kernel.org>,
	linux-mm@kvack.org, dm-devel@redhat.com,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND] slab: introduce the flag SLAB_MINIMIZE_WASTE
Date: Tue, 17 Apr 2018 09:45:27 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.20.1804170940340.17557@nuc-kabylake> (raw)
In-Reply-To: <alpine.LRH.2.02.1804161530360.19492@file01.intranet.prod.int.rdu2.redhat.com>

On Mon, 16 Apr 2018, Mikulas Patocka wrote:

> This patch introduces a flag SLAB_MINIMIZE_WASTE for slab and slub. This
> flag causes allocation of larger slab caches in order to minimize wasted
> space.
>
> This is needed because we want to use dm-bufio for deduplication index and
> there are existing installations with non-power-of-two block sizes (such
> as 640KB). The performance of the whole solution depends on efficient
> memory use, so we must waste as little memory as possible.

Hmmm. Can we come up with a generic solution instead?

This may mean relaxing the enforcement of the allocation max order a bit
so that we can get dense allocation through higher order allocs.

But then higher order allocs are generally seen as problematic.

Note that SLUB will fall back to smallest order already if a failure
occurs so increasing slub_max_order may not be that much of an issue.

Maybe drop the max order limit completely and use MAX_ORDER instead? That
means that callers need to be able to tolerate failures.

  reply	other threads:[~2018-04-17 14:45 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <alpine.LRH.2.02.1803201740280.21066@file01.intranet.prod.int.rdu2.redhat.com>
     [not found] ` <alpine.DEB.2.20.1803211024220.2175@nuc-kabylake>
     [not found]   ` <alpine.LRH.2.02.1803211153320.16017@file01.intranet.prod.int.rdu2.redhat.com>
     [not found]     ` <alpine.DEB.2.20.1803211226350.3174@nuc-kabylake>
     [not found]       ` <alpine.LRH.2.02.1803211425330.26409@file01.intranet.prod.int.rdu2.redhat.com>
     [not found]         ` <20c58a03-90a8-7e75-5fc7-856facfb6c8a@suse.cz>
     [not found]           ` <20180413151019.GA5660@redhat.com>
     [not found]             ` <ee8807ff-d650-0064-70bf-e1d77fa61f5c@suse.cz>
     [not found]               ` <20180416142703.GA22422@redhat.com>
     [not found]                 ` <alpine.LRH.2.02.1804161031300.24222@file01.intranet.prod.int.rdu2.redhat.com>
     [not found]                   ` <20180416144638.GA22484@redhat.com>
2018-04-16 19:32                     ` Mikulas Patocka
2018-04-17 14:45                       ` Christopher Lameter [this message]
2018-04-17 16:16                         ` Vlastimil Babka
2018-04-17 16:38                           ` Christopher Lameter
2018-04-17 19:09                             ` Mikulas Patocka
2018-04-17 17:26                           ` Mikulas Patocka
2018-04-17 19:13                             ` Vlastimil Babka
2018-04-17 19:06                         ` Mikulas Patocka
2018-04-18 14:55                           ` Christopher Lameter
2018-04-25 21:04                             ` Mikulas Patocka
2018-04-25 23:24                               ` Mikulas Patocka
2018-04-26 19:01                                 ` Christopher Lameter
2018-04-26 21:09                                   ` Mikulas Patocka
2018-04-27 16:41                                     ` Christopher Lameter
2018-04-27 19:19                                       ` Mikulas Patocka
2018-06-13 17:01                                         ` Mikulas Patocka
2018-06-13 18:16                                           ` Christoph Hellwig
2018-06-13 18:53                                             ` Mikulas Patocka
2018-04-26 18:51                               ` Christopher Lameter
     [not found]                     ` <alpine.LRH.2.02.1804161054410.17807@file01.intranet.prod.int.rdu2.redhat.com>
     [not found]                       ` <alpine.DEB.2.20.1804161018030.9397@nuc-kabylake>
     [not found]                         ` <alpine.LRH.2.02.1804161123400.17807@file01.intranet.prod.int.rdu2.redhat.com>
     [not found]                           ` <alpine.DEB.2.20.1804161043430.9622@nuc-kabylake>
     [not found]                             ` <alpine.LRH.2.02.1804161532480.19492@file01.intranet.prod.int.rdu2.redhat.com>
     [not found]                               ` <b0e6ccf6-06ce-e50b-840e-c8d3072382fd@suse.cz>
2018-04-16 21:01                                 ` Mikulas Patocka
2018-04-17 14:40                                   ` Christopher Lameter
2018-04-17 18:53                                     ` Mikulas Patocka
2018-04-17 21:42                                       ` Christopher Lameter

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=alpine.DEB.2.20.1804170940340.17557@nuc-kabylake \
    --to=cl@linux.com \
    --cc=akpm@linux-foundation.org \
    --cc=dm-devel@redhat.com \
    --cc=iamjoonsoo.kim@lge.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mpatocka@redhat.com \
    --cc=penberg@kernel.org \
    --cc=rientjes@google.com \
    --cc=snitzer@redhat.com \
    --cc=vbabka@suse.cz \
    --cc=willy@infradead.org \
    --subject='Re: [PATCH RESEND] slab: introduce the flag SLAB_MINIMIZE_WASTE' \
    /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).