From: Hugh Dickins <hugh.dickins@tiscali.co.uk>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Nitin Gupta <ngupta@vflare.org>,
hongshin@gmail.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 7/9] swap_info: swap count continuations
Date: Fri, 16 Oct 2009 03:24:57 +0100 (BST) [thread overview]
Message-ID: <Pine.LNX.4.64.0910160314310.2993@sister.anvils> (raw)
In-Reply-To: <20091016102951.a4f66a19.kamezawa.hiroyu@jp.fujitsu.com>
On Fri, 16 Oct 2009, KAMEZAWA Hiroyuki wrote:
> >
> My concern is that small numbers of swap_map[] which has too much refcnt
> can consume too much pages.
>
> If an entry is shared by 65535, 65535/128 = 512 page will be used.
> (I'm sorry if I don't undestand implementation correctly.)
Ah, you're thinking it's additive: perhaps because I use the name
"continuation", which may give that impression - maybe there's a
better name I can give it.
No, it's multiplicative - just like 999 is almost a thousand, not 27.
If an entry is shared by 65535, then it needs its original swap_map
page (0 to 0x3e) and a continuation page (0 to 0x7f) and another
continuation page (0 to 0x7f): if I've got my arithmetic right,
those three pages can hold a shared count up to 1032191, for
every one of that group of PAGE_SIZE neighbouring pages.
Hugh
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next prev parent reply other threads:[~2009-10-16 2:25 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-15 0:44 [PATCH 0/9] swap_info and swap_map patches Hugh Dickins
2009-10-15 0:46 ` [PATCH 1/9] swap_info: private to swapfile.c Hugh Dickins
2009-10-15 14:57 ` Rik van Riel
2009-10-15 23:10 ` Nigel Cunningham
2009-10-16 0:28 ` Hugh Dickins
2009-10-15 0:48 ` [PATCH 2/9] swap_info: change to array of pointers Hugh Dickins
2009-10-15 2:11 ` KAMEZAWA Hiroyuki
2009-10-15 22:41 ` Hugh Dickins
2009-10-15 23:04 ` Hugh Dickins
2009-10-15 23:47 ` KAMEZAWA Hiroyuki
2009-10-15 23:46 ` KAMEZAWA Hiroyuki
2009-10-15 15:02 ` Rik van Riel
2009-10-15 0:49 ` [PATCH 3/9] swap_info: include first_swap_extent Hugh Dickins
2009-10-15 0:50 ` [PATCH 4/9] swap_info: miscellaneous minor cleanups Hugh Dickins
2009-10-15 2:19 ` KAMEZAWA Hiroyuki
2009-10-15 22:01 ` Hugh Dickins
2009-10-16 0:41 ` [PATCH 4/9 v2] " Hugh Dickins
2009-10-15 0:52 ` [PATCH 5/9] swap_info: SWAP_HAS_CACHE cleanups Hugh Dickins
2009-10-15 2:37 ` KAMEZAWA Hiroyuki
2009-10-15 22:08 ` Hugh Dickins
2009-10-15 0:53 ` [PATCH 6/9] swap_info: swap_map of chars not shorts Hugh Dickins
2009-10-15 2:44 ` KAMEZAWA Hiroyuki
2009-10-15 22:17 ` Hugh Dickins
2009-10-15 23:52 ` KAMEZAWA Hiroyuki
2009-10-15 0:56 ` [PATCH 7/9] swap_info: swap count continuations Hugh Dickins
2009-10-15 3:30 ` KAMEZAWA Hiroyuki
2009-10-15 19:45 ` Andrew Morton
2009-10-15 21:17 ` David Rientjes
2009-10-16 0:21 ` Hugh Dickins
2009-10-15 23:53 ` Hugh Dickins
2009-10-16 1:29 ` KAMEZAWA Hiroyuki
2009-10-16 2:24 ` Hugh Dickins [this message]
2009-10-16 4:06 ` KAMEZAWA Hiroyuki
2009-10-16 4:49 ` Nitin Gupta
2009-10-16 6:30 ` [PATCH] mm: call pte_unmap() against a proper pte (Re: [PATCH 7/9] swap_info: swap count continuations) Daisuke Nishimura
2009-10-16 8:01 ` KAMEZAWA Hiroyuki
2009-10-15 0:57 ` [PATCH 8/9] swap_info: note SWAP_MAP_SHMEM Hugh Dickins
2009-10-15 3:32 ` KAMEZAWA Hiroyuki
2009-10-15 22:23 ` Hugh Dickins
2009-10-16 0:04 ` KAMEZAWA Hiroyuki
2009-10-15 0:58 ` [PATCH 9/9] swap_info: reorder its fields Hugh Dickins
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