Commit 957d1941 authored by Thomas Richter's avatar Thomas Richter Committed by Namhyung Kim
Browse files

perf bench: Fix perf bench syscall loop count 



Command 'perf bench syscall fork -l 100000' offers option -l to run for
a specified number of iterations. However this option is not always
observed. The number is silently limited to 10000 iterations as can be
seen:

Output before:
 # perf bench syscall fork -l 100000
 # Running 'syscall/fork' benchmark:
 # Executed 10,000 fork() calls
     Total time: 23.388 [sec]

    2338.809800 usecs/op
            427 ops/sec
 #

When explicitly specified with option -l or --loops, also observe
higher number of iterations:

Output after:
 # perf bench syscall fork -l 100000
 # Running 'syscall/fork' benchmark:
 # Executed 100,000 fork() calls
     Total time: 716.982 [sec]

    7169.829510 usecs/op
            139 ops/sec
 #

This patch fixes the issue for basic execve fork and getpgid.

Fixes: ece7f7c0 ("perf bench syscall: Add fork syscall benchmark")
Signed-off-by: default avatarThomas Richter <tmricht@linux.ibm.com>
Acked-by: default avatarSumanth Korikkar <sumanthk@linux.ibm.com>
Tested-by: default avatarAthira Rajeev <atrajeev@linux.ibm.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/20250304092349.2618082-1-tmricht@linux.ibm.com


Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
parent b627b443

tools/perf/bench/syscall.c

+13 −9
Original line number Diff line number Diff line
@@ -22,8 +22,7 @@ 
#define __NR_fork -1

#endif



#define LOOPS_DEFAULT 10000000

static	int loops = LOOPS_DEFAULT;

static	int loops;



static const struct option options[] = {

	OPT_INTEGER('l', "loop",	&loops,		"Specify number of loops"),
@@ -80,6 +79,18 @@ static int bench_syscall_common(int argc, const char **argv, int syscall) 
	const char *name = NULL;

	int i;



	switch (syscall) {

	case __NR_fork:

	case __NR_execve:

		/* Limit default loop to 10000 times to save time */

		loops = 10000;

		break;

	default:

		loops = 10000000;

		break;

	}



	/* Options -l and --loops override default above */

	argc = parse_options(argc, argv, options, bench_syscall_usage, 0);



	gettimeofday(&start, NULL);
@@ -94,16 +105,9 @@ static int bench_syscall_common(int argc, const char **argv, int syscall) 
			break;

		case __NR_fork:

			test_fork();

			/* Only loop 10000 times to save time */

			if (i == 10000)

				loops = 10000;

			break;

		case __NR_execve:

			test_execve();

			/* Only loop 10000 times to save time */

			if (i == 10000)

				loops = 10000;

			break;

		default:

			break;

		}