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SubjectRe: [[PATCH v6 09/10] powerpc/perf/hv-24x7: Use PMU_TXN_READ interface
On Thu, 2015-09-03 at 20:07 -0700, Sukadev Bhattiprolu wrote:
> 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 <>
> ---
> arch/powerpc/perf/hv-24x7.c | 166 ++++++++++++++++++++++++++++++++++++++++++-

This looks fine to me from an arch perspective. I assume the whole series can
go via tip-something?

Acked-by: Michael Ellerman <>


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