From: Dave Jones <davej@redhat.com>
To: davidm@hpl.hp.com
Cc: Andrew Morton <akpm@osdl.org>,
davidm@napali.hpl.hp.com, mpm@selenic.com,
linux-kernel@vger.kernel.org
Subject: Re: Fw: potential /dev/urandom scalability improvement
Date: Fri, 26 Mar 2004 18:23:26 +0000 [thread overview]
Message-ID: <20040326182326.GM22561@redhat.com> (raw)
In-Reply-To: <16484.29095.842735.102236@napali.hpl.hp.com>
On Fri, Mar 26, 2004 at 10:08:39AM -0800, David Mosberger wrote:
> > I think this may be dangerous on some CPUs, if may prefetch
> > past the end of the buffer. Ie, if PREFETCH_STRIDE was 32, and
> > len was 65, we'd end up prefetching 65->97. As well as being
> > wasteful to cachelines, this can crash if theres for eg
> > nothing mapped after the next page boundary.
>
> Huh? It only ever prefetches addresses that are _within_ the
> specified buffer. Of course it will prefetch entire cachelines, but I
> hope you're not worried about cachlines crossing page-boundaries! ;-))
The proposed only user of this may take care of this requirement, but
I'm more concerned someone not aware of this requirement using this
helper routine. At the least it deserves a comment IMO.
Dave
next prev parent reply other threads:[~2004-03-26 18:37 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 [this message]
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
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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