Re: [tip:core/locking] x86/smp: Move waiting on contended ticketlock out of line

From: Ingo Molnar
Date: Fri Feb 15 2013 - 10:58:07 EST

* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> Btw, it may end up that almost nobody cares. Modern CPU's are
> really good at handling the straightforward "save/restore to
> stack" instructions. One of the reasons I care is not
> performance per se, butu the fact that I still look at asm
> code every time I do any performance profiling, and it's
> absolutely horrible to see the code when you see "ugh, that's
> pointless". I'm sensitive to the spinlocks in particular,
> because we've gone back and forth on inlining them before, so
> I've seen this. But right now I don't think we inline the lock
> under normal configs *anyway*, so I guess it doesn't much
> matter.

Yes, right now we only inline non-debug spin_unlock() and
spin_unlock_irq() [on !PREEMPT] - because that was an
unconditional win.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at