From: Andrea Arcangeli <aarcange@redhat.com>
To: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org
Subject: Re: [PATCH] mm: compaction beware writeback
Date: Mon, 21 Mar 2011 13:32:17 +0100 [thread overview]
Message-ID: <20110321123217.GA5719@random.random> (raw)
In-Reply-To: <alpine.LSU.2.00.1103201927420.7353@sister.anvils>
On Sun, Mar 20, 2011 at 07:37:02PM -0700, Hugh Dickins wrote:
> On Sun, 20 Mar 2011, Andrea Arcangeli wrote:
> >
> > Interesting that slab allocates with order > 0 an object that is <4096
> > bytes. Is this related to slab_break_gfp_order?
>
> No, it's SLUB I'm using (partly for its excellent debugging, partly
> to trigger issues like this). Remember, that's SLUB's great weakness,
> that for optimal efficiency it relies upon higher order pages than you'd
> expect. It's much better since Christoph put in the ORDER_FALLBACK, but
> still makes a first attempt for a higher order page, which is liable to
> stir up page_alloc more than we'd like.
Ah ok, that explains it... I didn't realize you used SLUB sorry.
I use SLAB as it's measurably faster in most workloads even on larger
servers (but it will consume more memory on with an huge number of
cpus, up to 128 CPUs it's no big deal). My cellphone uses SLUB though
(kabi issues with evil rfs.ko or I would have switched already).
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next prev parent reply other threads:[~2011-03-21 12:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-20 6:27 [PATCH] mm: compaction beware writeback Hugh Dickins
2011-03-20 17:47 ` Andrea Arcangeli
2011-03-21 2:37 ` Hugh Dickins
2011-03-21 12:32 ` Andrea Arcangeli [this message]
2011-03-21 9:59 ` Mel Gorman
2011-03-29 8:27 ` Johannes Weiner
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