From: Benjamin LaHaise <bcrl@kvack.org>
To: Christoph Hellwig <hch@infradead.org>,
Ken Chen <kenchen@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [patch] cache pipe buf page address for non-highmem arch
Date: Fri, 23 Mar 2007 21:40:24 -0400 [thread overview]
Message-ID: <20070324014024.GL17334@kvack.org> (raw)
In-Reply-To: <20070323101452.GA15144@infradead.org>
On Fri, Mar 23, 2007 at 10:14:52AM +0000, Christoph Hellwig wrote:
> I think you're fixing the symptom here and not the cause. If calculating
> the virtual address of a page is so expensive on your setup it should
> define WANT_PAGE_VIRTUAL and we should always cache the virtual address
> in struct page. There's a lot more code, epecially in filesystems that's
> rather upset about a slow page_address.
Andi shot that down when I brought it up a while ago, as it does show
up in profiles for networking and other code paths. His argument is that
the loss of memory is excessive. Personally, I think the benefits of a
64 byte struct page on x86-64 outweigh the memory loss, as it means page
index to address translations are a simple shift.
-ben
--
"Time is of no importance, Mr. President, only life is important."
Don't Email: <zyntrop@kvack.org>.
next prev parent reply other threads:[~2007-03-24 1:40 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-23 0:51 [patch] cache pipe buf page address for non-highmem arch Ken Chen
2007-03-23 1:01 ` Andrew Morton
2007-03-24 0:48 ` Ken Chen
2007-03-27 4:15 ` Andrew Morton
2007-03-27 17:47 ` Ken Chen
2007-03-27 22:57 ` Zach Brown
2007-03-28 23:14 ` Andrew Morton
2007-03-28 23:21 ` Zach Brown
2007-03-28 23:34 ` Andrew Morton
2007-03-28 23:48 ` Jeremy Fitzhardinge
2007-03-23 10:14 ` Christoph Hellwig
2007-03-24 1:01 ` Ken Chen
2007-03-24 1:40 ` Benjamin LaHaise [this message]
2007-03-27 15:05 ` Andi Kleen
2007-03-27 15:01 ` Andi Kleen
2007-03-27 18:06 ` Ken Chen
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