diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/perf/hv-24x7.c | 13 |
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); |