Messages in this thread | | | Date | Wed, 21 Dec 2005 13:12:23 +1100 | From | Nick Piggin <> | Subject | Re: [patch 04/15] Generic Mutex Subsystem, add-atomic-call-func-x86_64.patch |
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Nicolas Pitre wrote: > On Tue, 20 Dec 2005, Linus Torvalds wrote:
>>IOW, why don't you just do >> >> ldr lr,[%0] >> subs lr, lr, %1 >> str lr,[%0] >> blmi failure >> >>as the _base_ timings, since that should be the common case. That's the >>drop-dead fastest UP case. > > > The above is 5 cycles. About the same as the preemption-safe swp-based > mutex implementation on non-Intel ARM. It is broken wrt interrupts when > the swp is not.
How it is broken WRT interrupts? (sorry, I haven't had it explained to me in words of two syllables or less)
-- SUSE Labs, Novell Inc.
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