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

Roman Zippel
2005-01-14T12:02:28Z

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