Messages in this thread | | | From | Stephane Eranian <> | Date | Tue, 24 Jan 2023 01:10:01 -0800 | Subject | Re: [PATCH 1/3] timekeeping: NMI safe converter from a given time to monotonic |
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On Tue, Jan 24, 2023 at 12:52 AM Thomas Gleixner <tglx@linutronix.de> wrote: > > On Mon, Jan 23 2023 at 10:27, kan liang wrote: > > From: Kan Liang <kan.liang@linux.intel.com> > > > > It's useful to provide a NMI safe function to convert a given time to > > monotonic. For example, the perf_event subsystem wants to convert a TSC > > of a PEBS record to a monotonic clock in a NMI handler. > > Why? That's a postprocessing problem, really. > Because you want to correlate samples captured by PEBS with samples from applications timestamped with a user available clock such as CLOCK_MONOTONIC, for instance. When I create a perf_event event and I stipulate that event_attr.clockid=MONOTONIC, I expect all the samples from that event to be timestamped using the same clock source, regardless of PEBS or IBS.
> Thanks, > > tglx
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