From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Hua Zhong <hzhong@gmail.com>
Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, linux-mm@kvack.org,
Hugh Dickins <hugh@veritas.com>
Subject: Re: [PATCH] fix can_share_swap_page() when !CONFIG_SWAP
Date: Mon, 08 May 2006 15:18:13 +1000 [thread overview]
Message-ID: <445ED495.3020401@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.64.0605071525550.2515@localhost.localdomain>
Hua Zhong wrote:
>Hi,
>
>can_share_swap_page() is used to check if the page has the last reference. This avoids allocating a new page for COW if it's the last page.
>
>However, if CONFIG_SWAP is not set, can_share_swap_page() is defined as 0, thus always causes a copy for the last COW page. The below simple patch fixes it.
>
>I'm not sure if it's the best fix. Maybe we should rename can_share_swap_page() and move it out of swapfile.c. Comments?
>
Looks like a good patch, nice catch. You should run it past Hugh but tend to
agree it would be nice to reuse the out of line can_share_swap_page,
which would
fold beautifully with PageSwapCache a constant 0.
Nick
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WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Hua Zhong <hzhong@gmail.com>
Cc: linux-kernel@vger.kernel.org, akpm@osdl.org, linux-mm@kvack.org,
Hugh Dickins <hugh@veritas.com>
Subject: Re: [PATCH] fix can_share_swap_page() when !CONFIG_SWAP
Date: Mon, 08 May 2006 15:18:13 +1000 [thread overview]
Message-ID: <445ED495.3020401@yahoo.com.au> (raw)
In-Reply-To: <Pine.LNX.4.64.0605071525550.2515@localhost.localdomain>
Hua Zhong wrote:
>Hi,
>
>can_share_swap_page() is used to check if the page has the last reference. This avoids allocating a new page for COW if it's the last page.
>
>However, if CONFIG_SWAP is not set, can_share_swap_page() is defined as 0, thus always causes a copy for the last COW page. The below simple patch fixes it.
>
>I'm not sure if it's the best fix. Maybe we should rename can_share_swap_page() and move it out of swapfile.c. Comments?
>
Looks like a good patch, nice catch. You should run it past Hugh but tend to
agree it would be nice to reuse the out of line can_share_swap_page,
which would
fold beautifully with PageSwapCache a constant 0.
Nick
--
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next prev parent reply other threads:[~2006-05-08 5:18 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-08 1:17 [PATCH] fix can_share_swap_page() when !CONFIG_SWAP Hua Zhong
2006-05-08 1:17 ` Hua Zhong
2006-05-08 5:18 ` Nick Piggin [this message]
2006-05-08 5:18 ` Nick Piggin
2006-05-08 12:45 ` Hugh Dickins
2006-05-08 12:45 ` Hugh Dickins
2006-05-09 1:59 ` Nick Piggin
2006-05-09 1:59 ` Nick Piggin
2006-05-09 11:25 ` Hugh Dickins
2006-05-09 11:25 ` Hugh Dickins
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