On Wed, 2011-12-21 at 18:19 -0800, Linus Torvalds wrote: > On Wed, Dec 21, 2011 at 9:05 AM, Tejun Heo <tj@xxxxxxxxxx> wrote: > > > > machines. (cc'ing arch) Does anyone have better insight here? How > > much more expensive are local irq save/restore compared to inc/dec'ing > > preempt count on various archs? > > I think powerpc does sw irq disable, so it's pretty much the same. On 64-bit only, but it's probably still better than going for an atomic op, our atomics tend to be handled at the l2 level and so are sloooow. .../... > So I really suspect that we could just say: "make the irq-safe version > be the *only* version", and no architecture will really care. Sure, it > can be more expensive, but it usually isn't. Only when done badly and > stupidly is it nasty. Agreed, keep it simple, or we'll just grow more bugs like this one. Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
