From 60035a3981a7f9d965df81a48a07b94e52ccd54f Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Wed, 16 Apr 2025 18:29:19 +0200 Subject: tools/perf: Allow to select the number of hash buckets Add the -b/ --buckets argument to specify the number of hash buckets for the private futex hash. This is directly passed to prctl(PR_FUTEX_HASH, PR_FUTEX_HASH_SET_SLOTS, buckets, immutable) and must return without an error if specified. The `immutable' is 0 by default and can be set to 1 via the -I/ --immutable argument. The size of the private hash is verified with PR_FUTEX_HASH_GET_SLOTS. If PR_FUTEX_HASH_GET_SLOTS failed then it is assumed that an older kernel was used without the support and that the global hash is used. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250416162921.513656-20-bigeasy@linutronix.de --- tools/perf/bench/futex-hash.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'tools/perf/bench/futex-hash.c') diff --git a/tools/perf/bench/futex-hash.c b/tools/perf/bench/futex-hash.c index b472eded521b..fdf133c9520f 100644 --- a/tools/perf/bench/futex-hash.c +++ b/tools/perf/bench/futex-hash.c @@ -18,9 +18,11 @@ #include #include #include +#include #include #include #include +#include #include #include "../util/mutex.h" @@ -50,9 +52,12 @@ struct worker { static struct bench_futex_parameters params = { .nfutexes = 1024, .runtime = 10, + .nbuckets = -1, }; static const struct option options[] = { + OPT_INTEGER( 'b', "buckets", ¶ms.nbuckets, "Specify amount of hash buckets"), + OPT_BOOLEAN( 'I', "immutable", ¶ms.buckets_immutable, "Make the hash buckets immutable"), OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"), OPT_UINTEGER('r', "runtime", ¶ms.runtime, "Specify runtime (in seconds)"), OPT_UINTEGER('f', "futexes", ¶ms.nfutexes, "Specify amount of futexes per threads"), @@ -118,6 +123,7 @@ static void print_summary(void) printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", !params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), (int)bench__runtime.tv_sec); + futex_print_nbuckets(¶ms); } int bench_futex_hash(int argc, const char **argv) @@ -161,6 +167,7 @@ int bench_futex_hash(int argc, const char **argv) if (!params.fshared) futex_flag = FUTEX_PRIVATE_FLAG; + futex_set_nbuckets_param(¶ms); printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n", getpid(), params.nthreads, params.nfutexes, params.fshared ? "shared":"private", params.runtime); -- cgit v1.2.3