Messages in this thread | | | Date | Tue, 9 Nov 1999 17:37:01 +0100 | From | Jamie Lokier <> | Subject | Re: PATCH 2.3.26: kmalloc GFP_ZERO |
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Jakub Jelinek wrote: > > Mikulas> GFP_ZERO is not so stupid idea. It allows us to implement > > Mikulas> something like zero-page cache. While processor has nothing > > Mikulas> to do, it can clear free pages, and when GFP_ZERO request > > Mikulas> comes, it returns page directly without clearing overhead. > > > > Which I doubt is a win anyway, all you do is to sit there and thrash > > your cache in the background. > > Even if you do it in a smart way (avoid trashing caches by bypassing them), > it turned out to be very little win (I have implemented it on sparc64 some > months ago and lmbench numbers were better just by a very small margin so I > scratched it).
A pre-zeroing thread was discussed a few months ago, and someone mentioned it was effective on some architecture.... Sadly I forget which.
Anyway, it's not jus overhead that's improved with pre-zeroing. Latency when a process suddenly needs new pages comes to mind.
-- Jamie
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