6.12-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Richter tmricht@linux.ibm.com
[ Upstream commit 957d194163bf983da98bf7ec7e4f86caff8cd0eb ]
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: ece7f7c0507c ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/bench/syscall.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-)
diff --git a/tools/perf/bench/syscall.c b/tools/perf/bench/syscall.c index ea4dfc07cbd6b..e7dc216f717f5 100644 --- a/tools/perf/bench/syscall.c +++ b/tools/perf/bench/syscall.c @@ -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; }