From: Christoph Hellwig <hch@infradead.org>
To: Andrew Morton <akpm@osdl.org>
Cc: Christoph Hellwig <hch@infradead.org>,
fujita.tomonori@lab.ntt.co.jp, michaelc@cs.wisc.edu,
linux-fsdevel@vger.kernel.org, ext2-devel@lists.sourceforge.net,
open-iscsi@googlegroups.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: allowed pages in the block later, was Re: [Ext2-devel] [PATCH] ext3: avoid sending down non-refcounted pages
Date: Mon, 12 Dec 2005 17:25:52 +0000 [thread overview]
Message-ID: <20051212172552.GA28652@infradead.org> (raw)
In-Reply-To: <20051210164736.6e4eaa3f.akpm@osdl.org>
On Sat, Dec 10, 2005 at 04:47:36PM -0800, Andrew Morton wrote:
> Christoph Hellwig <hch@infradead.org> wrote:
> >
> > The problem we're trying to solve here is how do implement network block
> > devices (nbd, iscsi) efficiently. The zero copy codepath in the networking
> > layer does need to grab additional references to pages. So to use sendpage
> > we need a refcountable page. pages used by the slab allocator are not
> > normally refcounted so try to do get_page/pub_page on them will break.
>
> I don't get it. Doing get_page/put_page on a slab-allocated page should do
> the right thing?
As Arjan mentioned, what would be the right thing? Delaying returning the
page to the page pool and disallow reuse until page count reaches zero?
All this seems highly impractical.
next prev parent reply other threads:[~2005-12-12 17:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-08 9:09 [PATCH] ext3: avoid sending down non-refcounted pages FUJITA Tomonori
2005-12-08 10:18 ` Andreas Dilger
2005-12-08 12:39 ` [Ext2-devel] " FUJITA Tomonori
2005-12-08 13:42 ` allowed pages in the block later, was " Christoph Hellwig
2005-12-08 13:58 ` Pekka Enberg
2005-12-12 17:27 ` allowed pages in the block later, was " Christoph Hellwig
2005-12-08 18:18 ` allowed pages in the block later, was Re: [Ext2-devel] " Mike Christie
2005-12-08 18:22 ` Mike Christie
2005-12-08 19:20 ` Pekka Enberg
2005-12-11 0:47 ` Andrew Morton
2005-12-11 8:44 ` allowed pages in the block later, was " Arjan van de Ven
2005-12-12 17:25 ` Christoph Hellwig [this message]
2005-12-12 20:12 ` allowed pages in the block later, was Re: [Ext2-devel] " Andrew Morton
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