On Thu, Oct 15, 2015 at 04:37:57PM -0700, Andi Kleen wrote: > One side effect is that the old retry loop is not possible anymore, > as the counters stay unacked for the majority of the PMI handler, > but that is not a big loss, as "profiling" the PMI was always > a bit dubious. For the old ack sequence it is still supported.
Its not a self profiling thing, its a safety feature. The interrupt very explicitly disables all PMU counters, which would make self profiling impossible. And note that the "perfevents: irq loop stuck!" WARN is still triggerable on my IVB (although I've not managed to find the root cause of that). What would happen with a 'stuck' event in the new scheme? > In principle the sequence should work on other CPUs too, but > since I only tested on Skylake it is only enabled there. I would very much like a reduction of the ack states. You introduced the late thing, which should also work for everyone, and now you introduce yet another variant. I would very much prefer a single ack scheme if at all possible. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/