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| author | Thomas Richter <tmricht@linux.ibm.com> | 2024-01-26 15:32:03 +0300 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2024-02-20 16:37:32 +0300 |
| commit | 82cb9b618531109824eb8e25b6a3da28d33178ac (patch) | |
| tree | cc695ff65ef627df733195c6e2ba5de0a4388dac /arch/s390/kernel/perf_pai_ext.c | |
| parent | fe861b0c8d0693cb65fd45b7e8c756937b5182ae (diff) | |
| download | linux-82cb9b618531109824eb8e25b6a3da28d33178ac.tar.xz | |
s390/pai: simplify event start function for perf stat
When an event is started, read the current value of the
PAI counter. This value is saved in event::hw.prev_count.
When an event is stopped, this value is subtracted from the current
value read out at event stop time. The difference is the delta
of this counter.
Simplify the logic and read the event value every time the event is
started. This scheme is identical to other device drivers.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/perf_pai_ext.c')
| -rw-r--r-- | arch/s390/kernel/perf_pai_ext.c | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/arch/s390/kernel/perf_pai_ext.c b/arch/s390/kernel/perf_pai_ext.c index 21a18eafb576..dd84c4d6fbe9 100644 --- a/arch/s390/kernel/perf_pai_ext.c +++ b/arch/s390/kernel/perf_pai_ext.c @@ -331,11 +331,8 @@ static void paiext_start(struct perf_event *event, int flags) u64 sum; if (!event->attr.sample_period) { /* Counting */ - if (!event->hw.last_tag) { - event->hw.last_tag = 1; - sum = paiext_getall(event); /* Get current value */ - local64_set(&event->hw.prev_count, sum); - } + sum = paiext_getall(event); /* Get current value */ + local64_set(&event->hw.prev_count, sum); } else { /* Sampling */ perf_sched_cb_inc(event->pmu); } |