Re: SMP syncronization on AMD processors (broken?)
From: Chuck Ebbert
Date: Sat Oct 08 2005 - 04:35:32 EST
On Thu, 06 Oct 2005 at 17:05:03 +0400, Kirill Korotaev wrote:
> The question is whether concurrent spin_lock()'s should
> acquire it in more or less "fair" fashinon or one of CPUs can starve any
> arbitrary time while others do reacquire it in a loop.
You neglected to say what CPU type you compiled the kernel for.
If it wasn't Pentium Pro maybe you could patch include/asm-i386/spinlock.h
line 82 (or the same place in x86-64) like this:
* (PPro errata 66, 92)
-#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
#define __raw_spin_unlock_string \
"movb $1,%0" \
The data might not make it out of the CPU write buffer without a locking
instruction doing the update.
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