[PATCH 4.9 049/130] perf bench: Fix numa report output code

Greg Kroah-Hartman
2018-08-23T08:10:54Z

From: Jiri Olsa <jolsa@kernel.org>

[ Upstream commit 983107072be1a39cbde67d45cb0059138190e015 ]

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 <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180620094036.17278-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/perf/bench/numa.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/tools/perf/bench/numa.c
+++ b/tools/perf/bench/numa.c
@@ -1093,7 +1093,7 @@ 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;
@@ -1249,7 +1249,8 @@ 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;