Messages in this thread | | | From | Alexander Shishkin <> | Subject | Re: [PATCH 2/3] perf/x86/intel/pt: Add an option to not force PSB+ on every schedule-in | Date | Thu, 30 Jul 2015 16:36:42 +0300 |
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Alexander Shishkin <alexander.shishkin@linux.intel.com> writes:
> It kinda does make a difference: inside PSB+ you get a TSC packet, which > carries the tsc timestamp as a payload, so, with the current behavior, > since you'll get one of those at every event schedule-in, you'll have > many more time synchronization points with the perf stream, but when the > default changes, suddenly your timestamps way further apart and the > decoder needs to put in additional guesswork to correlate those MMAP > events in the perf stream with the PT trace.
I spoke hastily, TSC packets will be generated on every schedule-in (as well as other packets that normally come in PSB+) regardless of the actual PSB, so scratch the above. Let me replace the above with a smaller patch.
Regards, -- Alex
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