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perf bench: Fix perf bench syscall loop count

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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: ece7f7c050 ("perf bench syscall: Add fork syscall benchmark")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Tested-by: Athira 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: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Thomas Richter
2025-03-04 10:23:49 +01:00
committed by Namhyung Kim
parent b627b443cc
commit 957d194163
1 changed files with 13 additions and 9 deletions
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22
tools/perf/bench/syscall.c
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@@ -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;
}