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authorJiri Kosina <jkosina@suse.cz>2011-04-26 10:22:15 +0200
committerJiri Kosina <jkosina@suse.cz>2011-04-26 10:22:59 +0200
commit07f9479a40cc778bc1462ada11f95b01360ae4ff (patch)
tree0676cf38df3844004bb3ebfd99dfa67a4a8998f5 /arch/powerpc/kernel/perf_event.c
parentath9k_hw: don't touch with treewide double semicolon removal (diff)
parentMerge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ecr... (diff)
downloadlinux-07f9479a40cc778bc1462ada11f95b01360ae4ff.tar.xz
linux-07f9479a40cc778bc1462ada11f95b01360ae4ff.zip
Merge branch 'master' into for-next
Fast-forwarded to current state of Linus' tree as there are patches to be applied for files that didn't exist on the old branch.
Diffstat (limited to 'arch/powerpc/kernel/perf_event.c')
-rw-r--r--arch/powerpc/kernel/perf_event.c39
1 files changed, 31 insertions, 8 deletions
diff --git a/arch/powerpc/kernel/perf_event.c b/arch/powerpc/kernel/perf_event.c
index 97e0ae414940..822f63008ae1 100644
--- a/arch/powerpc/kernel/perf_event.c
+++ b/arch/powerpc/kernel/perf_event.c
@@ -398,6 +398,25 @@ static int check_excludes(struct perf_event **ctrs, unsigned int cflags[],
return 0;
}
+static u64 check_and_compute_delta(u64 prev, u64 val)
+{
+ u64 delta = (val - prev) & 0xfffffffful;
+
+ /*
+ * POWER7 can roll back counter values, if the new value is smaller
+ * than the previous value it will cause the delta and the counter to
+ * have bogus values unless we rolled a counter over. If a coutner is
+ * rolled back, it will be smaller, but within 256, which is the maximum
+ * number of events to rollback at once. If we dectect a rollback
+ * return 0. This can lead to a small lack of precision in the
+ * counters.
+ */
+ if (prev > val && (prev - val) < 256)
+ delta = 0;
+
+ return delta;
+}
+
static void power_pmu_read(struct perf_event *event)
{
s64 val, delta, prev;
@@ -416,10 +435,11 @@ static void power_pmu_read(struct perf_event *event)
prev = local64_read(&event->hw.prev_count);
barrier();
val = read_pmc(event->hw.idx);
+ delta = check_and_compute_delta(prev, val);
+ if (!delta)
+ return;
} while (local64_cmpxchg(&event->hw.prev_count, prev, val) != prev);
- /* The counters are only 32 bits wide */
- delta = (val - prev) & 0xfffffffful;
local64_add(delta, &event->count);
local64_sub(delta, &event->hw.period_left);
}
@@ -449,8 +469,9 @@ static void freeze_limited_counters(struct cpu_hw_events *cpuhw,
val = (event->hw.idx == 5) ? pmc5 : pmc6;
prev = local64_read(&event->hw.prev_count);
event->hw.idx = 0;
- delta = (val - prev) & 0xfffffffful;
- local64_add(delta, &event->count);
+ delta = check_and_compute_delta(prev, val);
+ if (delta)
+ local64_add(delta, &event->count);
}
}
@@ -458,14 +479,16 @@ static void thaw_limited_counters(struct cpu_hw_events *cpuhw,
unsigned long pmc5, unsigned long pmc6)
{
struct perf_event *event;
- u64 val;
+ u64 val, prev;
int i;
for (i = 0; i < cpuhw->n_limited; ++i) {
event = cpuhw->limited_counter[i];
event->hw.idx = cpuhw->limited_hwidx[i];
val = (event->hw.idx == 5) ? pmc5 : pmc6;
- local64_set(&event->hw.prev_count, val);
+ prev = local64_read(&event->hw.prev_count);
+ if (check_and_compute_delta(prev, val))
+ local64_set(&event->hw.prev_count, val);
perf_event_update_userpage(event);
}
}
@@ -759,7 +782,7 @@ static int power_pmu_add(struct perf_event *event, int ef_flags)
/*
* If group events scheduling transaction was started,
- * skip the schedulability test here, it will be peformed
+ * skip the schedulability test here, it will be performed
* at commit time(->commit_txn) as a whole
*/
if (cpuhw->group_flag & PERF_EVENT_TXN)
@@ -1197,7 +1220,7 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
/* we don't have to worry about interrupts here */
prev = local64_read(&event->hw.prev_count);
- delta = (val - prev) & 0xfffffffful;
+ delta = check_and_compute_delta(prev, val);
local64_add(delta, &event->count);
/*