perf/stat: fix bug in handling events in error state
PATCH 1/1 perf/stat: fix bug in handling events in error state
From: Stephane Eranian <[email protected]>
(This is a patch has been sitting in the Intel CQM/CMT driver series
for a while, despite not depend on it. Sending it now independently since the series is being discarded.)
When an event is in error state, read() returns 0 instead of sizeof() buffer. In certain modes, such as interval printing, ignoring the 0 return value may cause bogus count deltas to be computed and thus invalid results printed.
This patch fixes this problem by modifying read_counters() to mark the event as not scaled (scaled = -1) to force the printout routine to show <NOT COUNTED>.
--- tools/perf/builtin-stat.c | 12 +++++++++--- tools/perf/util/evsel.c | 4 ++-- 2 files changed, 11 insertions(+), 5 deletions(-)
tools/perf/builtin-stat.c +9 -3
@@ -310,8 +310,12 @@ static int read_counter(struct perf_evsel *counter)struct perf_counts_values *count; count =perf_counts (counter->counts, cpu, thread); -if (perf_evsel__read (counter, cpu, thread, count)) +if (perf_evsel__read (counter, cpu, thread, count)) { + counter->counts->scaled =-1 ; +perf_counts (counter->counts, cpu, thread)->ena =0 ; +perf_counts (counter->counts, cpu, thread)->run =0 ;return -1 ; + }if (STAT_RECORD ) {if (perf_evsel__write_stat_event (counter, cpu, thread, count)) {
@@ -336,12 +340,14 @@ static int read_counter(struct perf_evsel *counter)static void read_counters (void ) {struct perf_evsel *counter; +int ret;evlist__for_each_entry (evsel_list, counter) { -if (read_counter (counter)) + ret =read_counter (counter); +if (ret)pr_debug ("failed to read counter %s\n" , counter->name); -if (perf_stat_process_counter (&stat_config, counter)) +if (ret ==0 &&perf_stat_process_counter (&stat_config, counter))pr_warning ("failed to process counter %s\n" , counter->name); } }
tools/perf/util/evsel.c +2 -2
@@ -1221,7 +1221,7 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,if (FD (evsel, cpu, thread) <0 )return -EINVAL ; -if (readn (FD (evsel, cpu, thread), count,sizeof (*count)) <0 ) +if (readn (FD (evsel, cpu, thread), count,sizeof (*count)) <=0 )return -errno;return 0 ;
@@ -1239,7 +1239,7 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evsel,if (evsel->counts ==NULL &&perf_evsel__alloc_counts (evsel, cpu +1 , thread +1 ) <0 )return -ENOMEM ; -if (readn (FD (evsel, cpu, thread), &count, nv *sizeof (u64)) <0 ) +if (readn (FD (evsel, cpu, thread), &count, nv *sizeof (u64)) <=0 )return -errno;perf_evsel__compute_deltas (evsel, cpu, thread, &count);
Signature · 1 line
2.12.2.715.g7642488e1d-goog
Quoted 12 lines · David Carrillo-Cisneros
From: Stephane Eranian <[email protected]>
(This is a patch has been sitting in the Intel CQM/CMT driver series
for a while, despite not depend on it. Sending it now independently since the series is being discarded.)When an event is in error state,
read()returns 0 instead ofsizeof()buffer. In certain modes, such as interval printing, ignoring the 0 return value may cause bogus count deltas to be computed and thus invalid results printed.
Quoted 6 lines
This patch fixes this problem by modifying
read_counters()to mark the event as not scaled (scaled = -1) to force the printout routine to show <NOT COUNTED>.Signed-off-by Stephane Eranian <[email protected]>Reviewed-by David Carrillo-Cisneros <[email protected]>
thanks,
jirka
tip-bot for Stephane Eranian
merge bot[tip:perf/core] perf stat: Fix bug in handling events in error state
In reply to David Carrillo-Cisnerosperf stat: Fix bug in handling events in error state
Commit-ID: db49a71798a38f3ddf3f3462703328dca39b1ac7 Gitweb: http://git.kernel.org/tip/db49a71798a38f3ddf3f3462703328dca39b1ac7 Author: Stephane Eranian <[email protected]> AuthorDate: Wed, 12 Apr 2017 11:23:01 -0700 Committer: Arnaldo Carvalho de Melo <[email protected]> CommitDate: Thu, 13 Apr 2017 10:40:36 -0300
perf stat: Fix bug in handling events in error state
(This is a patch has been sitting in the Intel CQM/CMT driver series for
a while, despite not depend on it. Sending it now independently since the series is being discarded.)
When an event is in error state, read() returns 0 instead of sizeof() buffer. In certain modes, such as interval printing, ignoring the 0 return value may cause bogus count deltas to be computed and thus invalid results printed.
This patch fixes this problem by modifying read_counters() to mark the event as not scaled (scaled = -1) to force the printout routine to show <NOT COUNTED>.
--- tools/perf/builtin-stat.c | 12 +++++++++--- tools/perf/util/evsel.c | 4 ++-- 2 files changed, 11 insertions(+), 5 deletions(-)
tools/perf/builtin-stat.c +9 -3
@@ -312,8 +312,12 @@ static int read_counter(struct perf_evsel *counter)struct perf_counts_values *count; count =perf_counts (counter->counts, cpu, thread); -if (perf_evsel__read (counter, cpu, thread, count)) +if (perf_evsel__read (counter, cpu, thread, count)) { + counter->counts->scaled =-1 ; +perf_counts (counter->counts, cpu, thread)->ena =0 ; +perf_counts (counter->counts, cpu, thread)->run =0 ;return -1 ; + }if (STAT_RECORD ) {if (perf_evsel__write_stat_event (counter, cpu, thread, count)) {
@@ -338,12 +342,14 @@ static int read_counter(struct perf_evsel *counter)static void read_counters (void ) {struct perf_evsel *counter; +int ret;evlist__for_each_entry (evsel_list, counter) { -if (read_counter (counter)) + ret =read_counter (counter); +if (ret)pr_debug ("failed to read counter %s\n" , counter->name); -if (perf_stat_process_counter (&stat_config, counter)) +if (ret ==0 &&perf_stat_process_counter (&stat_config, counter))pr_warning ("failed to process counter %s\n" , counter->name); } }
tools/perf/util/evsel.c +2 -2
@@ -1239,7 +1239,7 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,if (FD (evsel, cpu, thread) <0 )return -EINVAL ; -if (readn (FD (evsel, cpu, thread), count,sizeof (*count)) <0 ) +if (readn (FD (evsel, cpu, thread), count,sizeof (*count)) <=0 )return -errno;return 0 ;
@@ -1257,7 +1257,7 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evsel,if (evsel->counts ==NULL &&perf_evsel__alloc_counts (evsel, cpu +1 , thread +1 ) <0 )return -ENOMEM ; -if (readn (FD (evsel, cpu, thread), &count, nv *sizeof (u64)) <0 ) +if (readn (FD (evsel, cpu, thread), &count, nv *sizeof (u64)) <=0 )return -errno;perf_evsel__compute_deltas (evsel, cpu, thread, &count);