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authorSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>2016-01-26 07:05:36 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2016-03-10 14:56:55 +0300
commit2b206ee6b0df03a89783c6a9ada363122f918800 (patch)
treed31a1dca3ba011bbef8e3ddda9412d7e749bf4fe /arch/powerpc
parente5a5886d7ae32b7afebfffecca340e466e4be2d1 (diff)
downloadlinux-2b206ee6b0df03a89783c6a9ada363122f918800.tar.xz
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>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/perf/hv-24x7.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index b7a9a03ca59d..77b958f213a0 100644
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -1222,11 +1222,12 @@ static int h_24x7_event_init(struct perf_event *event)
return -EACCES;
}
- /* see if the event complains */
+ /* Get the initial value of the counter for this event */
if (single_24x7_request(event, &ct)) {
pr_devel("test hcall failed\n");
return -EIO;
}
+ (void)local64_xchg(&event->hw.prev_count, ct);
return 0;
}
@@ -1289,6 +1290,16 @@ static void h_24x7_event_read(struct perf_event *event)
h24x7hw = &get_cpu_var(hv_24x7_hw);
h24x7hw->events[i] = event;
put_cpu_var(h24x7hw);
+ /*
+ * Clear the event count so we can compute the _change_
+ * in the 24x7 raw counter value at the end of the txn.
+ *
+ * Note that we could alternatively read the 24x7 value
+ * now and save its value in event->hw.prev_count. But
+ * that would require issuing a hcall, which would then
+ * defeat the purpose of using the txn interface.
+ */
+ local64_set(&event->count, 0);
}
put_cpu_var(hv_24x7_reqb);