On Mon, Nov 13, 2017 at 11:33:43AM +0800, Peter Xu wrote: > On Fri, Nov 10, 2017 at 09:05:20AM +0100, Peter Zijlstra wrote: > > On Fri, Nov 10, 2017 at 03:10:17PM +0800, Peter Xu wrote: > > > I came to this when reading kvm_vcpu_wake_up(), so that only affects > > > some statistic which may not be that critical. However I don't know > > > whether there would be any other real use case that we would like to > > > know exactly whether a call to [s]wake_up() has really done something > > > or just returned with a NOP. > > > > > > Anyway, please let me know if you think the same change to wake_up() > > > would be meaningful, otherwise I can drop this patch and post another > > > KVM-only one to clean up the redundant callers of swait_active(), > > > since even if we dropped that list check in 35a2897c2a30, we'll do > > > that again in swake_up_locked(). > > > > See commits: > > > > 8cd641e3c7cb ("sched/wait: Add swq_has_sleeper()") > > 5e0018b3e39e ("kvm: Serialize wq active checks in kvm_vcpu_wake_up()") > > > > > > In any case, I don't think we want the change you propose. The numbers > > don't mean much and there's no point in making all the callers in the > > kernel slower for it. > > I see. And also we can introduce a new API for that if really needed. > > I'll repost with KVM only changes. Thanks for reviewing. Wait... I see that https://lkml.org/lkml/2017/9/5/622 seems to have fixed all the occurences. So I'll drop the series. Thanks, -- Peter Xu