Re: [PATCH] i386 spinlocks should use the full 32 bits, not only 8bits

From: Linus Torvalds
Date: Tue Oct 11 2005 - 11:04:59 EST

On Tue, 11 Oct 2005, Eric Dumazet wrote:
> As NR_CPUS might be > 128, and every spining CPU decrements the lock, we need
> to use more than 8 bits for a spinlock. The current (i386/x86_64)
> implementations have a (theorical) bug in this area.

I don't think there are any x86 machines with > 128 CPU's right now.

The advantage of the byte lock is that a "movb $0" is three bytes shorter
than a "movl $0". And that's the unlock sequence.

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