From: Christoph Lameter <cl@linux.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.cz>, azurIt <azurit@pobox.sk>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org,
Christian Casteyde <casteyde.christian@free.fr>,
Pekka Enberg <penberg@kernel.org>
Subject: Re: [patch 2/2] fs: buffer: move allocation failure loop into the allocator
Date: Wed, 4 Dec 2013 15:17:08 +0000 [thread overview]
Message-ID: <00000142be2f1de0-764bb035-adbc-4367-b2b4-bf05498510a6-000000@email.amazonses.com> (raw)
In-Reply-To: <20131203180717.94c013d1.akpm@linux-foundation.org>
On Tue, 3 Dec 2013, Andrew Morton wrote:
> > page = alloc_slab_page(alloc_gfp, node, oo);
> > if (unlikely(!page)) {
> > oo = s->min;
>
> What is the value of s->min? Please tell me it's zero.
It usually is.
> > @@ -1349,7 +1350,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
> > && !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
> > int pages = 1 << oo_order(oo);
> >
> > - kmemcheck_alloc_shadow(page, oo_order(oo), flags, node);
> > + kmemcheck_alloc_shadow(page, oo_order(oo), alloc_gfp, node);
>
> That seems reasonable, assuming kmemcheck can handle the allocation
> failure.
>
>
> Still I dislike this practice of using unnecessarily large allocations.
> What does it gain us? Slightly improved object packing density.
> Anything else?
The fastpath for slub works only within the bounds of a single slab page.
Therefore a larger frame increases the number of allocation possible from
the fastpath without having to use the slowpath and also reduces the
management overhead in the partial lists.
There is a kernel parameter that can be used to control the maximum order
slub_max_order
The default is PAGE_ALLOC_COSTLY_ORDER. See also
Documentation/vm/slub.txt.
Booting with slub_max_order=1 will force order 0/1 pages.
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next prev parent reply other threads:[~2013-12-04 15:17 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-08 20:58 [patch 1/2] mm: memcg: handle non-error OOM situations more gracefully Johannes Weiner
2013-10-08 20:58 ` [patch 2/2] fs: buffer: move allocation failure loop into the allocator Johannes Weiner
2013-10-11 20:51 ` Andrew Morton
2013-12-04 0:59 ` Andrew Morton
2013-12-04 1:52 ` Joonsoo Kim
2013-12-04 2:07 ` Andrew Morton
2013-12-04 2:42 ` Joonsoo Kim
2013-12-04 15:17 ` Christoph Lameter [this message]
2013-12-04 16:02 ` Joonsoo Kim
2013-12-04 16:33 ` Christoph Lameter
2013-12-05 8:44 ` Joonsoo Kim
2013-12-05 18:50 ` Christoph Lameter
2013-12-06 8:57 ` Joonsoo Kim
2013-12-13 6:58 ` Joonsoo Kim
2013-12-13 16:40 ` Christoph Lameter
2013-12-16 8:22 ` Joonsoo Kim
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