From: Andrew Morton <akpm@zip.com.au>
To: "David S. Miller" <davem@redhat.com>
Cc: mingo@elte.hu, bcrl@redhat.com, velco@fadata.bg,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Scalable page cache
Date: Mon, 26 Nov 2001 11:29:19 -0800 [thread overview]
Message-ID: <3C02980E.8EDED15D@zip.com.au> (raw)
In-Reply-To: <Pine.LNX.4.33.0111262115261.17043-100000@localhost.localdomain>, <20011126131641.A13955@redhat.com> <Pine.LNX.4.33.0111262115261.17043-100000@localhost.localdomain> <20011126.103327.18298379.davem@redhat.com>
"David S. Miller" wrote:
>
> From: Ingo Molnar <mingo@elte.hu>
> Date: Mon, 26 Nov 2001 21:29:39 +0100 (CET)
>
> so i'm not against removing (or improving) the hash [our patch in fact
> just left the hash alone], but the patch presented is not a win IMO.
>
> Maybe you should give it a test to find out for sure :)
umm.. I've never seen any numbers from you, David.
Correct me if I'm wrong, but the pagecache_hash cost is
significant in the following situations:
1: TUX, because its pagecache lookups are not associated with
a page copy. This copy makes the benefits of the patch
unmeasurable with other workloads.
1a: Other sendfile-intensive applications. (Theoretical benefit.
No benchmark results have been seen).
2: NUMA hardware, where the cost of cacheline transfer is much
higher.
ergo, there is no point in futzing with the pagecache_lock *at all*
until either TUX is merged, or we decide to support large-scale
NUMA hardware well, which will require changes in other places.
Prove me wrong. Please.
-
next prev parent reply other threads:[~2001-11-26 19:32 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-11-26 12:31 [PATCH] Scalable page cache Momchil Velikov
2001-11-26 17:22 ` Ingo Molnar
2001-11-26 17:23 ` Momchil Velikov
2001-11-26 18:16 ` Benjamin LaHaise
2001-11-26 18:42 ` Rik van Riel
2001-11-26 20:29 ` Ingo Molnar
2001-11-26 18:33 ` David S. Miller
2001-11-26 19:29 ` Andrew Morton [this message]
2001-11-26 19:35 ` David S. Miller
2001-11-26 18:34 ` Benjamin LaHaise
2001-11-26 20:40 ` Ingo Molnar
2001-11-26 19:19 ` Benjamin LaHaise
2001-11-26 21:00 ` Ingo Molnar
2001-11-26 20:43 ` Daniel Phillips
2001-11-26 19:49 ` Ingo Molnar
2001-11-26 18:08 ` Christoph Hellwig
2001-11-26 20:13 ` Ingo Molnar
2001-11-26 21:09 ` Ingo Molnar
2001-11-26 19:18 ` David S. Miller
2001-11-26 19:45 ` Andrew Morton
2001-11-26 19:57 ` David S. Miller
2001-11-26 20:03 ` Andrew Morton
2001-11-26 20:37 ` Linus Torvalds
2001-11-26 21:02 ` Andrew Morton
2001-11-26 22:23 ` Linus Torvalds
2001-11-26 22:49 ` Jeff Garzik
2001-11-26 23:06 ` Linus Torvalds
2001-11-26 21:10 ` Ingo Molnar
2001-11-26 17:29 ` Linus Torvalds
2001-11-26 20:03 ` Ingo Molnar
2001-11-26 18:02 ` David S. Miller
2001-11-26 18:11 ` Rik van Riel
2001-11-27 8:07 ` benchmark results: " Anton Blanchard
2001-11-26 18:52 ` [PATCH] " Daniel Phillips
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