• Sukadev Bhattiprolu's avatar
    powerpc/perf/hv-24x7: Display change in counter values · 2b206ee6
    Sukadev Bhattiprolu authored
    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: default avatarSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    2b206ee6
hv-24x7.c 36.5 KB