From: Arjan van de Ven <arjanv@redhat.com>
To: Andrew Morton <akpm@osdl.org>
Cc: davidm@hpl.hp.com, davidm@napali.hpl.hp.com, davej@redhat.com,
mpm@selenic.com, linux-kernel@vger.kernel.org
Subject: Re: Fw: potential /dev/urandom scalability improvement
Date: Sat, 27 Mar 2004 08:44:49 +0100 [thread overview]
Message-ID: <20040327074449.GA10596@devserv.devel.redhat.com> (raw)
In-Reply-To: <20040326131736.1cc6a939.akpm@osdl.org>
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On Fri, Mar 26, 2004 at 01:17:36PM -0800, Andrew Morton wrote:
> If someone does
>
> prefetch_range(4090, 20);
>
> on 4k pagesize, what should we do?
well if the datastructure you prefetch crosses pageboundary you know both
pages are safe to prefetch.
> Issuing a single
>
> prefetch 4090
>
> sounds reasonable.
>
> In that case I'm arranging for it to perform
>
> prefetch (4096 - 32)
>
> in that case, which seems neater.
well prefetch is defined as "get the cacheline the address is located in";
eg the cpu does the rounding to cacheline size for you.
(btw prefetch stride isn't the cacheline size! it's how far you're supposed
to prefetch ahead to get any useful gain, si for aligning and stuff it's
useless)
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next prev parent reply other threads:[~2004-03-27 7:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20040325141923.7080c6f0.akpm@osdl.org>
2004-03-25 22:47 ` Fw: potential /dev/urandom scalability improvement Matt Mackall
2004-03-26 1:45 ` David Mosberger
2004-03-26 2:00 ` Andrew Morton
2004-03-26 2:10 ` David Mosberger
2004-03-26 4:07 ` Matt Mackall
2004-03-26 4:19 ` Matt Mackall
2004-03-26 4:51 ` David Mosberger
2004-03-26 5:15 ` Matt Mackall
2004-03-26 5:24 ` David Mosberger
2004-03-26 11:06 ` Dave Jones
2004-03-26 18:08 ` David Mosberger
2004-03-26 18:23 ` Dave Jones
2004-03-26 21:31 ` David Mosberger
2004-03-26 18:49 ` Andrew Morton
2004-03-26 20:25 ` David Mosberger
2004-03-26 20:33 ` Andrew Morton
2004-03-26 20:45 ` Arjan van de Ven
2004-03-26 21:17 ` Andrew Morton
2004-03-27 7:44 ` Arjan van de Ven [this message]
2004-03-26 21:12 ` David Mosberger
[not found] <1DLZM-8aK-67@gated-at.bofh.it>
[not found] ` <1DLZM-8aK-65@gated-at.bofh.it>
[not found] ` <1DOE1-20o-17@gated-at.bofh.it>
[not found] ` <1DOXn-2k7-5@gated-at.bofh.it>
[not found] ` <1DXxI-Z7-39@gated-at.bofh.it>
[not found] ` <1E467-6KK-17@gated-at.bofh.it>
[not found] ` <1E4IT-7f3-21@gated-at.bofh.it>
2004-03-27 1:29 ` Andi Kleen
2004-03-27 15:48 ` Matt Mackall
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