* Linus Torvalds <[email protected]> wrote:
> No, the cache line arbitration doesn't know anything about "locked" vs
> "unlocked" instructions (it could, but there really is no point).
>
> The real issue is that locked instructions on x86 are serializing,
> which makes them extremely slow (compared to just a write), and then
> by being slow they effectively just make the window for another core
> bigger.
>
> IOW, it doesn't "fix" anything, it just hides the bug with timing.
yeah. I think Linux is i think the only OS on the planet that is using
the movb trick for unlock, it even triggered a hardware erratum ;) So it
might surprise some hw makers who might rely on the heuristics that each
critical section lock and unlock is a LOCK-ed instruction.
Ingo
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