Date: Thu, 30 Mar 2006 17:54:06 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Jens Axboe <axboe@suse.de>
Cc: linux-kernel@vger.kernel.org, torvalds@osdl.org
Subject: Re: [PATCH][RFC] splice support
Message-Id: <20060330175406.fbd6d82c.kamezawa.hiroyu@jp.fujitsu.com>
In-Reply-To: <20060329122841.GC8186@suse.de>
References: <20060329122841.GC8186@suse.de>
Organization: Fujitsu
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On Wed, 29 Mar 2006 14:28:41 +0200
Jens Axboe <axboe@suse.de> wrote:
>
> +	/*
> +	 * Get as many pages from the page cache as possible..
> +	 * Start IO on the page cache entries we create (we
> +	 * can assume that any pre-existing ones we find have
> +	 * already had IO started on them).
> +	 */
> +	i = find_get_pages(mapping, index, pages, array);
> +

It looks page caches in this array is hold by pipe until data is consumed.
So..this page cannot be reclaimd or migrated and hot-removed :).
I don't know about sendfile() but this looks client can hold server's memory,
when server uses sendfile() 64k/conn.

Is there a way to force these pages to be freed ? or page reclaimer can
know this page is held by splice ? (we need additional PG_flags to do this ?)

I think these pages are necessary to be held only when data in them is used.

--Kame


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