mirror of https://gitee.com/openkylin/linux.git
88a486132d
The 24x7 counters in Powerpc allow monitoring a large number of counters simultaneously. They also allow reading several counters in a single HCALL so we can get a more consistent snapshot of the system. Use the PMU's transaction interface to monitor and read several event counters at once. The idea is that users can group several 24x7 events into a single group of events. We use the following logic to submit the group of events to the PMU and read the values: pmu->start_txn() // Initialize before first event for each event in group pmu->read(event); // Queue each event to be read pmu->commit_txn() // Read/update all queuedcounters The ->commit_txn() also updates the event counts in the respective perf_event objects. The perf subsystem can then directly get the event counts from the perf_event and can avoid submitting a new ->read() request to the PMU. Thanks to input from Peter Zijlstra. Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Link: http://lkml.kernel.org/r/1441336073-22750-10-git-send-email-sukadev@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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