Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH] [9/58] x86_64: Always use builtin memcpy on gcc 4.3 | Date | Sun, 22 Jul 2007 01:27:35 +0200 |
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On Sunday 22 July 2007 01:16:42 Oleg Verych wrote: > * From: Andi Kleen <ak@suse.de> > * Date: Thu, 19 Jul 2007 11:54:53 +0200 (CEST) > > > > Jan asked to always use the builtin memcpy on gcc 4.3 mainline because > > it should generate better code than the old macro. Let's try it. > > Unfortunately such info is hard to find. The discuss@x86-64 list is > empty. So, let me ask how this memcpy relates to recently submitted > for glibc one [0]?
It doesn't relate at all. The kernel still uses its own memcpy.
Note that a lot of the traditional memcpy optimizations (like WC copies) are pointless in kernel space because the kernel rarely deals with continuous memory areas larger than a 4K page.
The only difference from the patch is that instead of using an own heuristic when to use an out of line memcpy trust gcc's heuristic.
-Andi
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