Messages in this thread | | | From | Vince Weaver <> | Date | Tue, 14 Mar 2017 23:41:10 -0400 (EDT) | Subject | perf: rdpmc mmap page time_enabled issue |
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So another obscure rdpmc problem, turned up by the PAPI regression tests.
If you use rdpmc, and your event is attached measuring another process, and then you ENABLE/DISABLE/ENABLE/rdpmc the event
somehow the userpg->time_enabled field gets a weird value and that completely confuses code expecting enabled!=running to mean multiplexing is happening.
Example:
Trying attach: * RDPMC 1 Event 0 -- count: 1058381 enabled ffe6935332c70240 running: 9d14f * RDPMC 1 Event 1 -- count: 623980 enabled ffe6935332c829b3 running: 9d350
the rdpmc count and running values are expected, but the enabled value is way off, it should match the running value.
If you want to test this out, I have a test case in perf_event_tests, (github.com/deater/perf_event_tests.git) tests/rdpmc/rdpmc_multiattach_papi
Vince
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