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SubjectRe: [patch 04/15] Generic Mutex Subsystem, add-atomic-call-func-x86_64.patch
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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