Messages in this thread | | | Date | Wed, 25 Jan 2006 10:56:42 +0100 | From | Nick Piggin <> | Subject | Re: [RFC] non-refcounted pages, application to slab? |
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On Wed, Jan 25, 2006 at 10:54:08AM +0100, Eric Dumazet wrote: > Nick Piggin a écrit : > > >@@ -2604,10 +2604,10 @@ static inline void *__cache_alloc(kmem_c > > > > local_irq_save(save_flags); > > objp = ____cache_alloc(cachep, flags); > >+ prefetchw(objp); > > local_irq_restore(save_flags); > > objp = cache_alloc_debugcheck_after(cachep, flags, objp, > > __builtin_return_address(0)); > >- prefetchw(objp); > > return objp; > > } > > I'm not sure why you moved this prefetchw(obj) : This is not related to > your 'non-refcounting' part, is it ? >
Stray hunk. Thanks.
Nick
> When I added this prefetchw in slab code, I did place it *after* the > local_irq_restore(save_flags); because I was not sure if the > serialization/barrier (popf) would force the cpu (x86/x86_64 in mind) to > either : > - finish all the loads (even if they are speculative/hints) (so giving a > bad latency) > - cancel the speculative loads (so prefetchw() *before* the > local_irq_restore() would be useless. > Makes sense.
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