Ming Lei, Thomas, Sorry if it is a bit late to jump in. On Mon, Aug 22, 2011 at 10:27 AM, Thomas Renninger <trenn@xxxxxxx> wrote: > On Saturday, August 20, 2011 04:40:09 AM Ming Lei wrote: >> Hi, >> >> 2011/8/20 Thomas Renninger <trenn@xxxxxxx>: >> > On Friday, August 19, 2011 05:04:04 PM tom.leiming@xxxxxxxxx wrote: >> >> From: Ming Lei <tom.leiming@xxxxxxxxx> >> >> >> >> This patch removes the 'cpu_id' parameter of the cpu_idle >> >> trace point, based on the ideas below: >> >> >> >> - the cpu_id which is passed to trace point is always the current >> >> cpu >> > Are you sure this will always be true? >> >> It is sure at least now, the only place to pass 'dev->cpu' is inside >> cpuidle_idle_call, > It was known that cpu_id is always the current cpu with current > implementation when this got introduced. > But the perf events API must not change back and forth for userspace > compatibility. Therefore the cpu_id was added in case > that future implementations want to pass info where the current cpu > is not the cpu which is sent to the sleep state. Agree. Let's keep the cpu_id field. > >> smp_processor_id() can't be used safely in preemptible context. > I expect the only side effect that could happen is that if smp_process_id > is interrupted you get the wrong core id on a cpu idle trace event. > This only happens if cpuidle is not used and even then should happen > very rarely, nothing to worry for a debug tool like that. > And it should get fixed if these idle functions get fully integrated into > cpuidle at some point of time. > > Thomas > Regards, Jean -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
