Messages in this thread | | | Subject | Re: [RFC] perf arm-spe: Track task context switch for cpu-mode events | From | James Clark <> | Date | Wed, 6 Oct 2021 15:06:25 +0100 |
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On 05/10/2021 11:06, German Gomez wrote: > Hi Leo, > > On 04/10/2021 07:26, Leo Yan wrote: >> Hi James, >> >> On Thu, Sep 30, 2021 at 04:08:52PM +0100, James Clark wrote: >>> On 23/09/2021 15:23, Leo Yan wrote: >>>> On Thu, Sep 16, 2021 at 02:01:21PM -0700, Namhyung Kim wrote: >> [...] >> I'd like to use the comparison method for the test: >> We should enable PID tracing and capture in the perf.data, when decode >> the trace data, we can based on context packet and based on the switch >> events to generate out two results, so we can check how the difference >> between these results. > > Yesterday we did some testing and found that there seems to be an exact > match between using context packets and switch events. However this only > applies when tracing in userspace (by adding the 'u' suffix to the perf > event). Otherwise we still see as much as 2% of events having the wrong > PID around the time of the switch. > > In order to measure this I applied Namhyung's patch and James's patch > from [1].
I thought that this had been applied already so I need to follow this up.
James
[...] > > [1] https://www.spinics.net/lists/linux-perf-users/msg12543.html >
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