4.9-stable review patch. If anyone has any objections, please let me know.
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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;