On Tue, Jan 07, 2014 at 01:52:31AM +0100, Andi Kleen wrote: > > > Also of course it requires disabling/enabling PT explicitly for > > > every perf message, which is slow. So you add at least 2*WRMSR cost > > > (thousands of cycles). > > > > That's just dumb, no flush the entire PT buffer into a few large > > records. > > How would that work? > > You mean a separate buffer and then copy or map? > > ------ > > Also here are some more problems with interleaving: > > A common PT config is to just run it as a ring buffer in the background > and only take the data out when something happens (sample, crash etc.) > > But the side band still needs to be logged and at arbitary times. > > So the PT wrapping will happen much more often than the perf wrapping.
So create two events, one for the PT stuff and one to track the side-band stuff. We have a NOP event for just this purpose. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
