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perf bench: Fix numa report output code

PATCH Applied Jiri Olsa 3 participants 3 messages Jun 20, 2018 – Jun 26, 2018 perf events

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Jiri Olsa

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#0 lore raw

PATCH 1/1 perf bench: Fix numa report output code

Currently we can hit following assert when running numa bench:

  $ perf bench numa mem -p 3 -t 1 -P 512 -s 100 -zZ0cm --thp 1
  perf: bench/numa.c:1577: __bench_numa: Assertion `!(!(((wait_stat) & 0x7f) == 0))' failed.

The assertion is correct, because we hit the SIGFPE in following line:

Thread 2.2 "thread 0/0" received signal SIGFPE, Arithmetic exception. [Switching to Thread 0x7fffd28c6700 (LWP 11750)]
0x000.. in worker_thread (__tdata=0x7.. ) at bench/numa.c:1257 1257 td->speed_gbs = bytes_done / (td->runtime_ns / NSEC_PER_SEC) / 1e9;

We don't check if the runtime is actually bigger than 1 second, and thus this might end up with zero division within FPU.

Adding the check to prevent this.

Link http://lkml.kernel.org/n/[email protected] open here
Signed-off-by Jiri Olsa <[email protected]>
---
 tools/perf/bench/numa.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
tools/perf/bench/numa.c +3 -2
index 63eb49082774..44195514b19e 100644
@@ -1098,7 +1098,7 @@ static void *worker_thread(void *__tdata)
 	u8 *global_data;
 	u8 *process_data;
 	u8 *thread_data;
-	u64 bytes_done;
+	u64 bytes_done, secs;
 	long work_done;
 	u32 l;
 	struct rusage rusage;

@@ -1254,7 +1254,8 @@ static void *worker_thread(void *__tdata)
 	timersub(&stop, &start0, &diff);
 	td->runtime_ns = diff.tv_sec * NSEC_PER_SEC;
 	td->runtime_ns += diff.tv_usec * NSEC_PER_USEC;
-	td->speed_gbs = bytes_done / (td->runtime_ns / NSEC_PER_SEC) / 1e9;
+	secs = td->runtime_ns / NSEC_PER_SEC;
+	td->speed_gbs = secs ? bytes_done / secs / 1e9 : 0;
 
 	getrusage(RUSAGE_THREAD, &rusage);
 	td->system_time_ns = rusage.ru_stime.tv_sec * NSEC_PER_SEC;
Signature · 1 line
2.13.6
maintainer Applied
#1 lore raw

Em Wed, Jun 20, 2018 at 11:40:36AM +0200, Jiri Olsa escreveu:

Quoted 12 lines

Currently we can hit following assert when running numa bench:

  $ perf bench numa mem -p 3 -t 1 -P 512 -s 100 -zZ0cm --thp 1
  perf: bench/numa.c:1577: __bench_numa: Assertion `!(!(((wait_stat) & 0x7f) == 0))' failed.

The assertion is correct, because we hit the SIGFPE in following line:

Thread 2.2 "thread 0/0" received signal SIGFPE, Arithmetic exception. [Switching to Thread 0x7fffd28c6700 (LWP 11750)]
0x000.. in worker_thread (__tdata=0x7.. ) at bench/numa.c:1257 1257 td->speed_gbs = bytes_done / (td->runtime_ns / NSEC_PER_SEC) / 1e9;

Quoted 7 lines

We don't check if the runtime is actually bigger than 1 second, and thus this might end up with zero division within FPU.

Adding the check to prevent this.

Link http://lkml.kernel.org/n/[email protected] open here
Signed-off-by Jiri Olsa <[email protected]>

thanks, applied to perf/urgent.

- Arnaldo

merge bot
#2 lore raw
In reply to Jiri Olsa
perf bench: Fix numa report output code
Commit-ID:  983107072be1a39cbde67d45cb0059138190e015
Gitweb:     https://git.kernel.org/tip/983107072be1a39cbde67d45cb0059138190e015
Author:     Jiri Olsa <[email protected]>
AuthorDate: Wed, 20 Jun 2018 11:40:36 +0200
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Mon, 25 Jun 2018 11:59:37 -0300

perf bench: Fix numa report output code

Currently we can hit following assert when running numa bench:

  $ perf bench numa mem -p 3 -t 1 -P 512 -s 100 -zZ0cm --thp 1
  perf: bench/numa.c:1577: __bench_numa: Assertion `!(!(((wait_stat) & 0x7f) == 0))' failed.

The assertion is correct, because we hit the SIGFPE in following line:

Thread 2.2 "thread 0/0" received signal SIGFPE, Arithmetic exception. [Switching to Thread 0x7fffd28c6700 (LWP 11750)]
0x000.. in worker_thread (__tdata=0x7.. ) at bench/numa.c:1257 1257 td->speed_gbs = bytes_done / (td->runtime_ns / NSEC_PER_SEC) / 1e9;

We don't check if the runtime is actually bigger than 1 second, and thus this might end up with zero division within FPU.

Adding the check to prevent this.

Signed-off-by Jiri Olsa <[email protected]>
Cc Alexander Shishkin <[email protected]>
Cc David Ahern <[email protected]>
Cc Namhyung Kim <[email protected]>
Cc Peter Zijlstra <[email protected]>
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Arnaldo Carvalho de Melo <[email protected]>
---
 tools/perf/bench/numa.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
tools/perf/bench/numa.c +3 -2
index 63eb49082774..44195514b19e 100644
@@ -1098,7 +1098,7 @@ static void *worker_thread(void *__tdata)
 	u8 *global_data;
 	u8 *process_data;
 	u8 *thread_data;
-	u64 bytes_done;
+	u64 bytes_done, secs;
 	long work_done;
 	u32 l;
 	struct rusage rusage;

@@ -1254,7 +1254,8 @@ static void *worker_thread(void *__tdata)
 	timersub(&stop, &start0, &diff);
 	td->runtime_ns = diff.tv_sec * NSEC_PER_SEC;
 	td->runtime_ns += diff.tv_usec * NSEC_PER_USEC;
-	td->speed_gbs = bytes_done / (td->runtime_ns / NSEC_PER_SEC) / 1e9;
+	secs = td->runtime_ns / NSEC_PER_SEC;
+	td->speed_gbs = secs ? bytes_done / secs / 1e9 : 0;
 
 	getrusage(RUSAGE_THREAD, &rusage);
 	td->system_time_ns = rusage.ru_stime.tv_sec * NSEC_PER_SEC;