Hi,
I'm resending the patches from James Yang and Kim Phillips that
improve the perf bench futex benchmarks. Noticibly:
patch1 makes use of util/cpumap.c
patch2/3 are the same as the original only that I've split
it into two and removed some bogus debug noise.
Davidlohr Bueso (3):
perf bench futex: Use cpumaps
perf bench futex: Add --affine-wakers option to wake-parallel
perf bench futex: sync waker threads
tools/perf/bench/futex-hash.c | 19 ++++++++-----
tools/perf/bench/futex-lock-pi.c | 23 +++++++++------
tools/perf/bench/futex-requeue.c | 22 +++++++++------
tools/perf/bench/futex-wake-parallel.c | 51 ++++++++++++++++++++++++++--------
tools/perf/bench/futex-wake.c | 18 +++++++-----
5 files changed, 90 insertions(+), 43 deletions(-)
--
2.13.6
From 1585886620465361589@xxx Mon Dec 04 20:28:58 +0000 2017
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From: James Yang <[email protected]>
Waker threads in the futex wake-parallel benchmark are started by a
loop using pthread_create(). However, there is no synchronization
for when the waker threads wake the waiting threads. Comparison of
the waker threads' measurement timestamps show they are not all
running concurrently because older waker threads finish their task
before newer waker threads even start.
This patch uses a barrier to better synchronize the waker threads.
Cc: Kim Phillips <[email protected]>
Signed-off-by: James Yang <[email protected]
Signed-off-by: Davidlohr Bueso <[email protected]>
---
tools/perf/bench/futex-wake-parallel.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/tools/perf/bench/futex-wake-parallel.c b/tools/perf/bench/futex-wake-parallel.c
index c04e207ea37c..55bff8673d31 100644
--- a/tools/perf/bench/futex-wake-parallel.c
+++ b/tools/perf/bench/futex-wake-parallel.c
@@ -43,6 +43,7 @@ static bool affine_wakers = false;
static unsigned int nblocked_threads = 0, nwaking_threads = 0;
static pthread_mutex_t thread_lock;
static pthread_cond_t thread_parent, thread_worker;
+static pthread_barrier_t barrier;
static struct stats waketime_stats, wakeup_stats;
static unsigned int threads_starting;
static int futex_flag = 0;
@@ -66,6 +67,8 @@ static void *waking_workerfn(void *arg)
struct thread_data *waker = (struct thread_data *) arg;
struct timeval start, end;
+ pthread_barrier_wait(&barrier);
+
gettimeofday(&start, NULL);
waker->nwoken = futex_wake(&futex, nwakes, futex_flag);
@@ -87,6 +90,8 @@ static void wakeup_threads(struct thread_data *td, pthread_attr_t thread_attr,
pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_JOINABLE);
+ pthread_barrier_init(&barrier, NULL, nwaking_threads + 1);
+
/* create and block all threads */
for (i = 0; i < nwaking_threads; i++) {
/*
@@ -110,9 +115,13 @@ static void wakeup_threads(struct thread_data *td, pthread_attr_t thread_attr,
err(EXIT_FAILURE, "pthread_create");
}
+ pthread_barrier_wait(&barrier);
+
for (i = 0; i < nwaking_threads; i++)
if (pthread_join(td[i].worker, NULL))
err(EXIT_FAILURE, "pthread_join");
+
+ pthread_barrier_destroy(&barrier);
}
static void *blocked_workerfn(void *arg __maybe_unused)
--
2.13.6
From 1585216163958344436@xxx Mon Nov 27 10:52:21 +0000 2017
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