From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: davidm@hpl.hp.com
Cc: Linus Torvalds <torvalds@transmeta.com>,
linux-kernel@vger.kernel.org, davidm@napali.hpl.hp.com
Subject: Re: adjust prefetch in free_one_pgd()
Date: 02 Aug 2002 18:58:53 +0100 [thread overview]
Message-ID: <1028311133.18317.96.camel@irongate.swansea.linux.org.uk> (raw)
In-Reply-To: <15690.46452.806917.37660@napali.hpl.hp.com>
On Fri, 2002-08-02 at 17:38, David Mosberger wrote:
> >>>>> On 02 Aug 2002 18:49:27 +0100, Alan Cox <alan@lxorguk.ukuu.org.uk> said:
>
> Alan> I can't think of anything cachable with nasty side effects we
> Alan> might encounter right now but one day someone will do it just
> Alan> to be annoying.
>
> Cacheable and side-effects don't go together. Even without explicit
> software prefetches, most modern CPUs will happily and aggressively
> prefetch stuff from cacheable translations.
Yes we got burned on that with the latest AMD processors. They prefetch
into an area we accidentally have marked with differing cachabilities
between kernel and user space when using the nv binary driver stuff (but
its our bug not theirs). There's a horrid hack in 2.4.19rc to deal with
it pending merging the proper patches
next prev parent reply other threads:[~2002-08-02 16:39 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-02 0:12 David Mosberger
2002-08-02 13:04 ` Alan Cox
2002-08-02 15:39 ` David Mosberger
2002-08-02 15:46 ` Linus Torvalds
2002-08-02 15:56 ` Dave Jones
2002-08-02 15:59 ` Linus Torvalds
2002-08-02 16:04 ` Dave Jones
2002-08-02 17:49 ` Alan Cox
2002-08-02 16:38 ` David Mosberger
2002-08-02 17:58 ` Alan Cox [this message]
2002-08-02 16:53 ` David Mosberger
2002-08-03 16:59 ` David Woodhouse
2002-08-03 17:22 ` Linus Torvalds
2002-08-03 17:39 ` David Woodhouse
2002-08-03 19:36 ` Linus Torvalds
2002-08-03 22:03 ` David Woodhouse
2002-08-03 22:40 ` Linus Torvalds
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