powerpc/perf/hv-24x7: Display change in counter values
For 24x7 counters, perf displays the raw value of the 24x7 counter, which
is a monotonically increasing value.
perf stat -C 0 -e \
'hv_24x7/HPM_0THRD_NON_IDLE_CCYC__PHYS_CORE,core=1/' \
sleep 1
Performance counter stats for 'CPU(s) 0':
9,105,403,170 hv_24x7/HPM_0THRD_NON_IDLE_CCYC__PHYS_CORE,core=1/
0.000425751 seconds time elapsed
In the typical usage of 'perf stat' this counter value is not as useful
as the _change_ in the counter value over the duration of the application.
Have h_24x7_event_init() set the event's prev_count to the raw value of
the 24x7 counter at the time of initialization. When the application
terminates, hv_24x7_event_read() will compute the change in value and
report to the perf tool. Similarly, for the transaction interface, clear
the event count to 0 at the beginning of the transaction.
perf stat -C 0 -e \
'hv_24x7/HPM_0THRD_NON_IDLE_CCYC__PHYS_CORE,core=1/' \
sleep 1
Performance counter stats for 'CPU(s) 0':
245,758 hv_24x7/HPM_0THRD_NON_IDLE_CCYC__PHYS_CORE,core=1/
1.006366383 seconds time elapsed
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
1 file changed