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Date: Fri, 20 May 2022 18:08:10 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
LKML <linux-kernel@...r.kernel.org>,
Ian Rogers <irogers@...gle.com>,
linux-perf-users@...r.kernel.org
Subject: [PATCH 1/2] perf lock: Do not discard broken lock stats
Currently it discards a lock_stat for a lock instance when there's a
broken lock_seq_stat in a single task for the lock. But it also means
that the existing (and later) valid lock stat info for that lock will
be discarded as well.
This is not ideal since we can lose many valuable info because of a
single failure. Actually those failures are indepent to the existing
stat. So we can only discard the broken lock_seq_stat but keep the
valid lock_stat.
The discarded lock_seq_stat will be reallocated in a subsequent event
with SEQ_STATE_UNINITIALIZED which will be ignored until it see the
start of the next sequence. So it should be ok just free it.
Before:
$ perf lock report -F acquired,contended,avg_wait
Warning:
Processed 1401603 events and lost 18 chunks!
Check IO/CPU overload!
Name acquired contended avg wait (ns)
rcu_read_lock 251225 0 0
&(ei->i_block_re... 8731 0 0
&sb->s_type->i_l... 8731 0 0
hrtimer_bases.lock 5261 0 0
hrtimer_bases.lock 2626 0 0
hrtimer_bases.lock 1953 0 0
hrtimer_bases.lock 1382 0 0
cpu_hotplug_lock 1350 0 0
hrtimer_bases.lock 1273 0 0
hrtimer_bases.lock 1269 0 0
hrtimer_bases.lock 1198 0 0
...
New:
Name acquired contended avg wait (ns)
rcu_read_lock 251225 0 0
tk_core.seq.seqc... 54074 0 0
&xa->xa_lock 17470 0 0
&ei->i_es_lock 17464 0 0
&ei->i_raw_lock 9391 0 0
&mapping->privat... 8734 0 0
&ei->i_data_sem 8731 0 0
&(ei->i_block_re... 8731 0 0
&sb->s_type->i_l... 8731 0 0
jiffies_seq.seqc... 6953 0 0
&mm->mmap_lock 6889 0 0
balancing 5768 0 0
hrtimer_bases.lock 5261 0 0
...
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/builtin-lock.c | 64 +++++++++++++++------------------------
1 file changed, 25 insertions(+), 39 deletions(-)
diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index cdfe1d4ced4b..7ceb12e30719 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -65,7 +65,7 @@ struct lock_stat {
u64 wait_time_min;
u64 wait_time_max;
- int discard; /* flag of blacklist */
+ int broken; /* flag of blacklist */
int combined;
};
@@ -384,9 +384,6 @@ static void combine_lock_stats(struct lock_stat *st)
ret = !!st->name - !!p->name;
if (ret == 0) {
- if (st->discard)
- goto out;
-
p->nr_acquired += st->nr_acquired;
p->nr_contended += st->nr_contended;
p->wait_time_total += st->wait_time_total;
@@ -399,10 +396,7 @@ static void combine_lock_stats(struct lock_stat *st)
if (p->wait_time_max < st->wait_time_max)
p->wait_time_max = st->wait_time_max;
- /* now it got a new !discard record */
- p->discard = 0;
-
-out:
+ p->broken |= st->broken;
st->combined = 1;
return;
}
@@ -415,15 +409,6 @@ static void combine_lock_stats(struct lock_stat *st)
rb_link_node(&st->rb, parent, rb);
rb_insert_color(&st->rb, &sorted);
-
- if (st->discard) {
- st->nr_acquired = 0;
- st->nr_contended = 0;
- st->wait_time_total = 0;
- st->avg_wait_time = 0;
- st->wait_time_min = ULLONG_MAX;
- st->wait_time_max = 0;
- }
}
static void insert_to_result(struct lock_stat *st,
@@ -560,8 +545,6 @@ static int report_lock_acquire_event(struct evsel *evsel,
ls = lock_stat_findnew(addr, name);
if (!ls)
return -ENOMEM;
- if (ls->discard)
- return 0;
ts = thread_stat_findnew(sample->tid);
if (!ts)
@@ -599,9 +582,11 @@ static int report_lock_acquire_event(struct evsel *evsel,
case SEQ_STATE_ACQUIRING:
case SEQ_STATE_CONTENDED:
broken:
- /* broken lock sequence, discard it */
- ls->discard = 1;
- bad_hist[BROKEN_ACQUIRE]++;
+ /* broken lock sequence */
+ if (!ls->broken) {
+ ls->broken = 1;
+ bad_hist[BROKEN_ACQUIRE]++;
+ }
list_del_init(&seq->list);
free(seq);
goto end;
@@ -629,8 +614,6 @@ static int report_lock_acquired_event(struct evsel *evsel,
ls = lock_stat_findnew(addr, name);
if (!ls)
return -ENOMEM;
- if (ls->discard)
- return 0;
ts = thread_stat_findnew(sample->tid);
if (!ts)
@@ -657,9 +640,11 @@ static int report_lock_acquired_event(struct evsel *evsel,
case SEQ_STATE_RELEASED:
case SEQ_STATE_ACQUIRED:
case SEQ_STATE_READ_ACQUIRED:
- /* broken lock sequence, discard it */
- ls->discard = 1;
- bad_hist[BROKEN_ACQUIRED]++;
+ /* broken lock sequence */
+ if (!ls->broken) {
+ ls->broken = 1;
+ bad_hist[BROKEN_ACQUIRED]++;
+ }
list_del_init(&seq->list);
free(seq);
goto end;
@@ -688,8 +673,6 @@ static int report_lock_contended_event(struct evsel *evsel,
ls = lock_stat_findnew(addr, name);
if (!ls)
return -ENOMEM;
- if (ls->discard)
- return 0;
ts = thread_stat_findnew(sample->tid);
if (!ts)
@@ -709,9 +692,11 @@ static int report_lock_contended_event(struct evsel *evsel,
case SEQ_STATE_ACQUIRED:
case SEQ_STATE_READ_ACQUIRED:
case SEQ_STATE_CONTENDED:
- /* broken lock sequence, discard it */
- ls->discard = 1;
- bad_hist[BROKEN_CONTENDED]++;
+ /* broken lock sequence */
+ if (!ls->broken) {
+ ls->broken = 1;
+ bad_hist[BROKEN_CONTENDED]++;
+ }
list_del_init(&seq->list);
free(seq);
goto end;
@@ -740,8 +725,6 @@ static int report_lock_release_event(struct evsel *evsel,
ls = lock_stat_findnew(addr, name);
if (!ls)
return -ENOMEM;
- if (ls->discard)
- return 0;
ts = thread_stat_findnew(sample->tid);
if (!ts)
@@ -767,9 +750,11 @@ static int report_lock_release_event(struct evsel *evsel,
case SEQ_STATE_ACQUIRING:
case SEQ_STATE_CONTENDED:
case SEQ_STATE_RELEASED:
- /* broken lock sequence, discard it */
- ls->discard = 1;
- bad_hist[BROKEN_RELEASE]++;
+ /* broken lock sequence */
+ if (!ls->broken) {
+ ls->broken = 1;
+ bad_hist[BROKEN_RELEASE]++;
+ }
goto free_seq;
default:
BUG_ON("Unknown state of lock sequence found!\n");
@@ -854,10 +839,11 @@ static void print_result(void)
bad = total = 0;
while ((st = pop_from_result())) {
total++;
- if (st->discard) {
+ if (st->broken)
bad++;
+ if (!st->nr_acquired)
continue;
- }
+
bzero(cut_name, 20);
if (strlen(st->name) < 20) {
--
2.36.1.124.g0e6072fb45-goog
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