On Tue, 6 Jan 2009, Ingo Molnar wrote: > > The thing i like most about Peter's patch (compared to most other adaptive > spinning approaches i've seen, which all sucked as they included various > ugly heuristics complicating the whole thing) is that it solves the "how > long should we spin" question elegantly: we spin until the owner runs on a > CPU. The other way around, you mean: we spin until the owner is no longer holding a cpu. I agree that it's better than the normal "spin for some random time" model, but I can't say I like the "return 0" cases where it just retries the whole loop if the semaphore was gotten by somebody else instead. Sounds like an easyish live-lock to me. I also still strongly suspect that whatever lock actually needs this, should be seriously re-thought. But apart from the "return 0" craziness I at least dont' _hate_ this patch. Do we have numbers? Do we know which locks this matters on? Linus -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
