Messages in this thread | | | Date | Mon, 17 Nov 2014 13:24:00 -0800 | From | Sukadev Bhattiprolu <> | Subject | Re: [PATCH v8 02/14] perf: Add AUX area to ring buffer for raw data streams |
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Alexander Shishkin [alexander.shishkin@linux.intel.com] wrote: | From: Peter Zijlstra <peterz@infradead.org> | | This patch introduces "AUX space" in the perf mmap buffer, intended for | exporting high bandwidth data streams to userspace, such as instruction | flow traces. | | AUX space is a ring buffer, defined by aux_{offset,size} fields in the | user_page structure, and read/write pointers aux_{head,tail}, which abide | by the same rules as data_* counterparts of the main perf buffer.
The "format" of this raw stream of data can differ across processors (and architecutres) correct ? i.e the perf tool processing of this aux data will also differ across processors ?
Power8 processors support what we call 24x7 counters that collect info on a large number of events. The current 24x7 support in (arch/powerpc/perf/hv-24x7.c) currently uses reading one counter at a time using the pmu->read() interface.
We are looking for ways to export much larger number of counters through one pmu->read() or another call. I am trying to see if the hv-24x7 pmu could use this aux interface and then have/implement a helper in perf tool to extract the counter values.
Sukadev
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