Messages in this thread | | | Date | Tue, 11 Oct 2005 18:36:29 +0200 | From | Eric Dumazet <> | Subject | Re: [PATCH] i386 spinlocks should use the full 32 bits, not only 8 bits |
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Linus Torvalds a écrit : > > 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.
1) Would you prefer to change arch/i386/Kconfig
config NR_CPUS int "Maximum number of CPUs (2-255)" range 2 255
2) The unlock sequence is not anymore inlined. It appears twice or three times in the kernel.
3) i386 code is often taken as the base when a port is done. For example x86_64 has the same problem.
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