From: Konstantin Khlebnikov <khlebnikov@parallels.com>
To: Pekka Enberg <penberg@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Christoph Lameter <cl@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Matt Mackall <mpm@selenic.com>,
"mgorman@suse.de" <mgorman@suse.de>
Subject: Re: [PATCH] mm-slab: allocate kmem_cache with __GFP_REPEAT
Date: Wed, 20 Jul 2011 17:50:29 +0400 [thread overview]
Message-ID: <4E26DD25.4010707@parallels.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1107201638520.4921@tiger>
Pekka Enberg wrote:
> On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote:
>>> The changelog isn't that convincing, really. This is kmem_cache_create()
>>> so I'm surprised we'd ever get NULL here in practice. Does this fix some
>>> problem you're seeing? If this is really an issue, I'd blame the page
>>> allocator as GFP_KERNEL should just work.
>>
>> nf_conntrack creates separate slab-cache for each net-namespace,
>> this patch of course not eliminates the chance of failure, but makes it more
>> acceptable.
>
> I'm still surprised you are seeing failures. mm/slab.c hasn't changed
> significantly in a long time. Why hasn't anyone reported this before? I'd
> still be inclined to shift the blame to the page allocator... Mel,
> Christoph?
>
> On Wed, 20 Jul 2011, Konstantin Khlebnikov wrote:
>> struct kmem_size for slub is more compact, it uses pecpu-pointers instead of
>> dumb NR_CPUS-size array.
>> probably better to fix this side...
>
> So how big is 'struct kmem_cache' for your configuration anyway? Fixing
> the per-cpu data structures would be nice but I'm guessing it'll be
> slightly painful for mm/slab.c.
With NR_CPUS=4096 and MAX_NUMNODES=512 its over 9k!
so it require order-4 page, meanwhile PAGE_ALLOC_COSTLY_ORDER is 3
>
> Pekka
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next prev parent reply other threads:[~2011-07-20 13:50 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-20 12:16 Konstantin Khlebnikov
2011-07-20 13:14 ` Pekka Enberg
2011-07-20 13:28 ` Konstantin Khlebnikov
2011-07-20 13:42 ` Pekka Enberg
2011-07-20 13:50 ` Konstantin Khlebnikov [this message]
2011-07-20 13:53 ` Pekka Enberg
2011-07-20 15:36 ` Christoph Lameter
2011-07-20 13:59 ` Konstantin Khlebnikov
2011-07-20 13:54 ` Christoph Lameter
2011-07-20 14:20 ` Mel Gorman
2011-07-20 14:32 ` Konstantin Khlebnikov
2011-07-20 14:40 ` Eric Dumazet
2011-07-20 14:47 ` Konstantin Khlebnikov
2011-07-20 13:43 ` Mel Gorman
2011-07-20 13:56 ` Christoph Lameter
2011-07-20 14:08 ` Eric Dumazet
2011-07-20 14:52 ` Christoph Lameter
2011-07-20 15:09 ` Eric Dumazet
2011-07-20 15:34 ` Christoph Lameter
2011-07-20 15:56 ` Eric Dumazet
2011-07-20 16:17 ` Christoph Lameter
2011-07-20 16:31 ` Eric Dumazet
2011-07-20 17:04 ` Eric Dumazet
2011-07-20 17:13 ` Christoph Lameter
2011-07-20 17:28 ` Pekka Enberg
2011-07-20 17:37 ` Christoph Lameter
2011-07-20 17:41 ` Pekka Enberg
2011-07-20 18:07 ` Matt Mackall
2011-07-21 7:18 ` Konstantin Khlebnikov
2011-07-20 19:09 ` Mel Gorman
2011-07-31 11:41 ` Konstantin Khlebnikov
2011-07-31 11:44 ` Pekka Enberg
2011-07-21 8:43 ` Eric Dumazet
2011-07-21 15:27 ` Christoph Lameter
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