Messages in this thread | | | Date | Wed, 25 Jan 2006 10:54:08 +0100 | From | Eric Dumazet <> | Subject | Re: [RFC] non-refcounted pages, application to slab? |
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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 ?
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.
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