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On Tue, 15 Jul 2003 23:32:48 -0700 David Mosberger <davidm@napali.hpl.hp.com> wrote: > DaveM> No, I mean "bypass L2 cache on miss" for stores. Don't tell > DaveM> me IA64 doesn't have that? 8) I certainly didn't mean "always > DaveM> bypass L2 cache" for stores :-) > > What I'm saying is that I almost always want copy_user() to put the > destination data in the cache, even if it isn't cached yet. No you don't :-) If you miss, you do a bypass to main memory. Then when the app asks for the data (if it even does at all, consider that) it get's a clean copy in it's L2 cache. Overall it's more efficient this way. > Many copy_user() calls are for for data structures that > easily fit in the cache and the data is usually used quickly afterwards. Absolutely correct. We can't use the cache bypass-on-miss stores on sparc64 unless the copy is at least a couple of cachelines in size. It all works out, don't worry :-) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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