Messages in this thread | | | Date | Mon, 11 Oct 2021 07:32:39 +0000 | From | Hyeonggon Yoo <> | Subject | Re: [PATCH] mm, slub: Use prefetchw instead of prefetch |
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On Mon, Oct 11, 2021 at 09:20:36AM +0200, Christoph Lameter wrote: > On Fri, 8 Oct 2021, Hyeonggon Yoo wrote: > > > It's certain that an object will be not only read, but also > > written after allocation. > > get_freepointer is used in multiple code path not only in allocation. It > is for example used when scanning through a freelist. > > With this change all objects get needlessly dirtied and the cross cpu > cache contention is increased.
I didn't touch get_freepointer and there's only one caller of prefetch_freepointer.
My change was not adding additional prefetch on get_freepointer, but changing existing prefetch into prefetchw.
The prefetch was introcued by commit 0ad9500e16fe ("slub: prefetch next freelist pointer in slab_alloc()") that you ACKed in 2011.
Do you think removeing existing prefetch is better than changing it from prefetch to prefetchw?
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