Re: page table lock patch V15 [0/7]: overview

From: Roman Zippel <zippel_at_linux-m68k.org>
Date: 2005-01-14 23:02:28
Hi,

On Fri, 14 Jan 2005, Andi Kleen wrote:

> > But there might be a loss in the UP case. Spinlocks are optimized away, 
> > but your cmpxchg emulation enables/disables interrupts with every access.
> 
> Only for 386s and STI/CLI is quite cheap there.

But it's still not free and what about other archs? Why not just check 
__HAVE_ARCH_CMPXCHG and provide a replacement, which is guaranteed cheaper 
if no interrupt synchronisation is needed. 

bye, Roman
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Received on Fri Jan 14 07:04:29 2005

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