Messages in this thread | | | Subject | Re: adjust prefetch in free_one_pgd() | From | Alan Cox <> | Date | 02 Aug 2002 18:58:53 +0100 |
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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
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