Re: [PATCH] mm/slab.c : prefetchw the start of new allocated objects

From: Ingo Molnar
Date: Fri Jul 29 2005 - 05:16:58 EST

* Eric Dumazet <dada1@xxxxxxxxxxxxx> wrote:

> local_irq_restore(save_flags);
> objp = cache_alloc_debugcheck_after(cachep, flags, objp, __builtin_return_address(0));
> + prefetchw(objp);
> return objp;

the idea is good, but i'd suggest to do the prefetchw a bit earlier,
right where we calculate objp. Furthermore, it might make sense to only
trigger the prefetchw in the alloc-miss (non-per-CPU cache) case. There
it's almost surely a win, in the per-CPU cache case it's not always.

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