On Tue, 19 May 2015, Steven Rostedt wrote: > On Tue, 19 May 2015 10:35:32 -0500 (CDT) > Christoph Lameter <cl@xxxxxxxxx> wrote: > > > On Thu, 19 Mar 2015, Steven Rostedt wrote: > > > > > On Thu, 19 Mar 2015 15:16:25 -0700 > > > Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > So I don't think the ring-buffer change is necessarily _wrong_, but if > > > > this is a performance issue, why don't we just fix it up for the > > > > generic case rather than for just one user? > > > > > > I totally agree with your analysis, but it's up to Christoph to come up > > > with an answer to your questions. > > > > Something beyond: Do not use this_cpu_* when preemption is already > > off but use __this_cpu_*? > > I think the question was, why exactly does the generic this_cpu_read() > require disabling preemption? What breaks if it is not disabled? Ok I answered that before. There is a cache line population/eviction issue (because it may happen on the wrong cache) but basically I think its mostly there for symmetries sake. We could remove this_cpu_read/write and let __this_cpu_read()/__this_cpu_write be used in non preemptible contexts. -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html