Messages in this thread | | | Date | Thu, 18 Aug 2005 00:27:14 +0900 | From | Akira Tsukamoto <> | Subject | Re: [RFC] [PATCH] cache pollution aware __copy_from_user_ll() |
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I am resubmitting this because it seems to be lost when I posted the before yesterday.
------------------------------------ Arjan van de Ven mentioned: > The only comment/question I have is about the use of prefetchnta; that > might have cache-evicting properties as well (eg evict the cache of the > original of the copy, eg the userspace memory). Is that really the right > approach? > In addition, my measurements show that removing the prefetch from the > main copy loop is a gain because the modern cpus have an autoprefetcher > already in the hardware.
My computer with Athlon K7 was faster with manually prefetching, but I did not know it is already becoming obsolete.
It was pretty while ago, but I also made a similar copy_user function; http://www.suna-asobi.com/~akira-t/linux/k7-copy-user/K7-copy-47.patch I add comments on each item in the copy function. It was basically inspired from Takahashi's intel faster copy function.
I also have some explanation about the speedup for pipelined cpu. http://www.suna-asobi.com/~akira-t/linux/k7-copy-user/copy_for_highlypipelined_cpu.txt
It was originally discussed in this thread, http://marc.theaimsgroup.com/?l=linux-kernel&m=103742983924070&w=2
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