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[83.244.142.114]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4887a34a638sm15216880f8f.9.2026.09.26.12.04.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 12:04:53 -0700 (PDT) From: Michal Pluta To: acme@kernel.org, namhyung@kernel.org Cc: Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Darren Hart , Davidlohr Bueso , =?UTF-8?q?Andr=C3=A9=20Almeida?= , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH 3/8] perf bench futex: Use the whole timeval for elapsed times Date: Sat, 26 Sep 2026 20:04:02 +0100 Message-ID: <20260926190407.1106421-4-michalpl2003@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260926190407.1106421-1-michalpl2003@gmail.com> References: <20260926190407.1106421-1-michalpl2003@gmail.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Several futex benchmarks read only one field of the struct timeval that timersub() produces, so part of the elapsed time is lost. 'futex wake', 'futex wake-parallel' and 'futex requeue' print tv_usec, so a run that takes 1.5 s is shown as 500 ms. 'futex hash' and 'futex lock-pi' divide their operation count by tv_sec, which overstates the throughput when a run is stopped early, and gives 0 if that happens within the first second. Their "total secs" is truncated in the same way. Use the whole timeval and print "total secs" with two decimals. With --runtime=0 the rate is now computed over the time that actually elapsed, instead of showing 0. Fixes: 27db78307481 ("perf bench: Add futex-wake microbenchmark") Fixes: 0fb298cf95c0 ("perf bench: Add futex-requeue microbenchmark") Fixes: a043971141f1 ("perf bench: Add futex-hash microbenchmark") Fixes: d2f3f5d2e9ca ("perf bench futex: Add lock_pi stresser") Fixes: d65817b4e707 ("perf bench futex: Support parallel waker threads") Assisted-by: LLM Signed-off-by: Michal Pluta --- tools/perf/bench/futex-hash.c | 12 ++++++++---- tools/perf/bench/futex-lock-pi.c | 12 ++++++++---- tools/perf/bench/futex-requeue.c | 8 +++++--- tools/perf/bench/futex-wake-parallel.c | 8 ++++++-- tools/perf/bench/futex-wake.c | 6 ++++-- 5 files changed, 31 insertions(+), 15 deletions(-) diff --git a/tools/perf/bench/futex-hash.c b/tools/perf/bench/futex-hash.c index 7e29f04da744..32b88df8ee6d 100644 --- a/tools/perf/bench/futex-hash.c +++ b/tools/perf/bench/futex-hash.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -118,18 +119,19 @@ static void print_summary(void) unsigned long avg = avg_stats(&throughput_stats); double stddev = stddev_stats(&throughput_stats); - printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", + printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %.2f\n", !params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), - (int)bench__runtime.tv_sec); + bench__runtime.tv_sec + bench__runtime.tv_usec / (double)USEC_PER_SEC); futex_print_nbuckets(¶ms); } int bench_futex_hash(int argc, const char **argv) { int ret = 0; cpu_set_t *cpuset; struct sigaction act; unsigned int i; + u64 runtime_us; pthread_attr_t thread_attr; struct worker *worker = NULL; struct perf_cpu_map *cpu; @@ -229,9 +231,11 @@ int bench_futex_hash(int argc, const char **argv) cond_destroy(&thread_worker); mutex_destroy(&thread_lock); + runtime_us = (u64)bench__runtime.tv_sec * USEC_PER_SEC + bench__runtime.tv_usec; + for (i = 0; i < params.nthreads; i++) { - unsigned long t = bench__runtime.tv_sec > 0 ? - worker[i].ops / bench__runtime.tv_sec : 0; + unsigned long t = runtime_us ? + (u64)worker[i].ops * USEC_PER_SEC / runtime_us : 0; update_stats(&throughput_stats, t); if (!params.silent) { if (params.nfutexes == 1) diff --git a/tools/perf/bench/futex-lock-pi.c b/tools/perf/bench/futex-lock-pi.c index 40640b674427..7190f5102e09 100644 --- a/tools/perf/bench/futex-lock-pi.c +++ b/tools/perf/bench/futex-lock-pi.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -66,9 +67,9 @@ static void print_summary(void) unsigned long avg = avg_stats(&throughput_stats); double stddev = stddev_stats(&throughput_stats); - printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", + printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %.2f\n", !params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), - (int)bench__runtime.tv_sec); + bench__runtime.tv_sec + bench__runtime.tv_usec / (double)USEC_PER_SEC); futex_print_nbuckets(¶ms); } @@ -168,6 +169,7 @@ int bench_futex_lock_pi(int argc, const char **argv) { int ret = 0; unsigned int i; + u64 runtime_us; struct sigaction act; struct perf_cpu_map *cpu; @@ -233,9 +235,11 @@ int bench_futex_lock_pi(int argc, const char **argv) cond_destroy(&thread_worker); mutex_destroy(&thread_lock); + runtime_us = (u64)bench__runtime.tv_sec * USEC_PER_SEC + bench__runtime.tv_usec; + for (i = 0; i < params.nthreads; i++) { - unsigned long t = bench__runtime.tv_sec > 0 ? - worker[i].ops / bench__runtime.tv_sec : 0; + unsigned long t = runtime_us ? + (u64)worker[i].ops * USEC_PER_SEC / runtime_us : 0; update_stats(&throughput_stats, t); if (!params.silent) diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c index 0748b0fd689e..5d4708f40c60 100644 --- a/tools/perf/bench/futex-requeue.c +++ b/tools/perf/bench/futex-requeue.c @@ -223,6 +223,7 @@ int bench_futex_requeue(int argc, const char **argv) for (j = 0; j < bench_repeat && !done; j++) { unsigned int nrequeued = 0, wakeups = 0; struct timeval start, end, runtime; + u64 runtime_us; /* create, launch & block all threads */ block_threads(worker, cpu); @@ -267,23 +268,24 @@ int bench_futex_requeue(int argc, const char **argv) gettimeofday(&end, NULL); timersub(&end, &start, &runtime); + runtime_us = (u64)runtime.tv_sec * USEC_PER_SEC + runtime.tv_usec; update_stats(&requeued_stats, nrequeued); - update_stats(&requeuetime_stats, runtime.tv_usec); + update_stats(&requeuetime_stats, runtime_us); if (!params.silent) { if (!params.pi) printf("[Run %d]: Requeued %d of %d threads in " "%.4f ms\n", j + 1, nrequeued, params.nthreads, - runtime.tv_usec / (double)USEC_PER_MSEC); + runtime_us / (double)USEC_PER_MSEC); else { nrequeued -= wakeups; printf("[Run %d]: Awoke and Requeued (%d+%d) of " "%d threads in %.4f ms\n", j + 1, wakeups, nrequeued, params.nthreads, - runtime.tv_usec / (double)USEC_PER_MSEC); + runtime_us / (double)USEC_PER_MSEC); } } diff --git a/tools/perf/bench/futex-wake-parallel.c b/tools/perf/bench/futex-wake-parallel.c index a089d8ee4b02..fa70b7d4b473 100644 --- a/tools/perf/bench/futex-wake-parallel.c +++ b/tools/perf/bench/futex-wake-parallel.c @@ -192,7 +192,9 @@ static void print_run(struct thread_data *waking_worker, unsigned int run_num) init_stats(&__waketime_stats); for (i = 0; i < params.nwakes; i++) { - update_stats(&__waketime_stats, waking_worker[i].runtime.tv_usec); + update_stats(&__waketime_stats, + (u64)waking_worker[i].runtime.tv_sec * USEC_PER_SEC + + waking_worker[i].runtime.tv_usec); update_stats(&__wakeup_stats, waking_worker[i].nwoken); } @@ -229,7 +231,9 @@ static void do_run_stats(struct thread_data *waking_worker) unsigned int i; for (i = 0; i < params.nwakes; i++) { - update_stats(&waketime_stats, waking_worker[i].runtime.tv_usec); + update_stats(&waketime_stats, + (u64)waking_worker[i].runtime.tv_sec * USEC_PER_SEC + + waking_worker[i].runtime.tv_usec); update_stats(&wakeup_stats, waking_worker[i].nwoken); } diff --git a/tools/perf/bench/futex-wake.c b/tools/perf/bench/futex-wake.c index 58427bb55c03..12a75be077a0 100644 --- a/tools/perf/bench/futex-wake.c +++ b/tools/perf/bench/futex-wake.c @@ -191,6 +191,7 @@ int bench_futex_wake(int argc, const char **argv) for (j = 0; j < bench_repeat && !done; j++) { unsigned int nwoken = 0; struct timeval start, end, runtime; + u64 runtime_us; /* create, launch & block all threads */ block_threads(worker, cpu); @@ -211,14 +212,15 @@ int bench_futex_wake(int argc, const char **argv) params.nwakes, futex_flag); gettimeofday(&end, NULL); timersub(&end, &start, &runtime); + runtime_us = (u64)runtime.tv_sec * USEC_PER_SEC + runtime.tv_usec; update_stats(&wakeup_stats, nwoken); - update_stats(&waketime_stats, runtime.tv_usec); + update_stats(&waketime_stats, runtime_us); if (!params.silent) { printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n", j + 1, nwoken, params.nthreads, - runtime.tv_usec / (double)USEC_PER_MSEC); + runtime_us / (double)USEC_PER_MSEC); } for (i = 0; i < params.nthreads; i++) { -- 2.43.0