Messages in this thread | | | Subject | Re: [RFC PATCH 2/2] perf stat: Use event group to simulate PMI on PMI-less hardware counter | From | Peter Zijlstra <> | Date | Wed, 10 Nov 2010 13:21:49 +0100 |
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On Wed, 2010-11-10 at 14:15 +0800, Lin Ming wrote: > Some hardware counters(for example, Intel RAPL) can't generate interrupt > when overflow. So we need to simulate the interrupt to periodically > record the counter values. Otherwise, the counter may overflow and the > wrong value is read. > > This patch uses event group to simulate PMI as suggested by Peter > Zijlstra, http://marc.info/?l=linux-kernel&m=128220854801819&w=2 > > create_group_counters() will create a group with 2 events, one hrtimer > based event as the group leader, and the other event to count. The > hrtimer is fired periodically, so the sibling event can record its > counter value periodically as well.
I'm terribly confused here....
- you introduce perf_event_attr:pmi_simulate, but then you never implement it -- nor do we need it afaict.
- you use grouped counters for perf-stat, perf-stat doesn't use sampling so I don't see a need to group events to simulate the PMI.
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