Re: [BUG] long freezes on thinkpad t60

[Ingo Molnar]

* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> 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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