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From: Christoph Lameter <cl@linux.com>
To: Simon Jeons <simon.jeons@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Mel Gorman <mgorman@suse.de>, Hugh Dickins <hughd@google.com>,
	Rik van Riel <riel@redhat.com>, Minchan Kim <minchan@kernel.org>,
	Pekka Enberg <penberg@kernel.org>, Matt Mackall <mpm@selenic.com>
Subject: Re: [PATCH 2/3] mm, slub: count freed pages via rcu as this task's reclaimed_slab
Date: Tue, 9 Apr 2013 14:32:22 +0000	[thread overview]
Message-ID: <0000013def363b50-9a16dd09-72ad-494f-9c25-17269fc3aab3-000000@email.amazonses.com> (raw)
In-Reply-To: <5163E194.3080600@gmail.com>

On Tue, 9 Apr 2013, Simon Jeons wrote:

> > +	int pages = 1 << compound_order(page);
>
> One question irrelevant this patch. Why slab cache can use compound
> page(hugetlbfs pages/thp pages)? They are just used by app to optimize tlb
> miss, is it?

Slab caches can use any order pages because these pages are never on
the LRU and are not part of the page cache. Large continuous physical
memory means that objects can be arranged in a more efficient way in the
page. This is particularly useful for larger objects where we might use a
lot of memory because objects do not fit well into a 4k page.

It also reduces the slab page management if higher order pages are used.
In the case of slub the page size also determines the number of objects
that can be allocated/freed without the need for some form of
synchronization.

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  reply	other threads:[~2013-04-09 14:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-09  1:21 [PATCH 1/3] mm, vmscan: count accidental reclaimed pages failed to put into lru Joonsoo Kim
2013-04-09  1:21 ` [PATCH 2/3] mm, slub: count freed pages via rcu as this task's reclaimed_slab Joonsoo Kim
2013-04-09  9:38   ` Simon Jeons
2013-04-09 14:32     ` Christoph Lameter [this message]
2013-04-10  3:20       ` Simon Jeons
2013-04-10 13:54         ` Christoph Lameter
2013-04-11  3:46           ` Simon Jeons
2013-04-11 15:03             ` Christoph Lameter
2013-04-09 14:28   ` Christoph Lameter
2013-04-10  5:26     ` Joonsoo Kim
2013-04-10 13:57       ` Christoph Lameter
2013-04-10 14:24         ` JoonSoo Kim
2013-04-09  1:21 ` [PATCH 3/3] mm, slab: " Joonsoo Kim
2013-04-09  5:55 ` [PATCH 1/3] mm, vmscan: count accidental reclaimed pages failed to put into lru Minchan Kim
2013-04-10  5:48   ` Joonsoo Kim
2013-04-10  6:03     ` Minchan Kim
2013-04-09  7:19 ` Wanpeng Li
2013-04-09  7:19 ` Wanpeng Li

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