Commit 0123bb91 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

selftests: ublk: set CPU affinity before thread initialization 



Move ublk_thread_set_sched_affinity() call before ublk_thread_init()
to ensure memory allocations during thread initialization occur on
the correct NUMA node. This leverages Linux's first-touch memory
policy for better NUMA locality.

Also convert ublk_thread_set_sched_affinity() to use
pthread_setaffinity_np() instead of sched_setaffinity(), as the
pthread API is the proper interface for setting thread affinity in
multithreaded programs.

Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent c28ba6b6

tools/testing/selftests/ublk/kublk.c

+10 −4
Original line number Diff line number Diff line
@@ -839,7 +839,7 @@ static int ublk_process_io(struct ublk_thread *t) 
static void ublk_thread_set_sched_affinity(const struct ublk_thread *t,

		cpu_set_t *cpuset)

{

        if (sched_setaffinity(0, sizeof(*cpuset), cpuset) < 0)

	if (pthread_setaffinity_np(pthread_self(), sizeof(*cpuset), cpuset) < 0)

		ublk_err("ublk dev %u thread %u set affinity failed",

				t->dev->dev_info.dev_id, t->idx);

}
@@ -862,15 +862,21 @@ static void *ublk_io_handler_fn(void *data) 
	t->dev = info->dev;

	t->idx = info->idx;



	/*

	 * IO perf is sensitive with queue pthread affinity on NUMA machine

	 *

	 * Set sched_affinity at beginning, so following allocated memory/pages

	 * could be CPU/NUMA aware.

	 */

	if (info->affinity)

		ublk_thread_set_sched_affinity(t, info->affinity);



	ret = ublk_thread_init(t, info->extra_flags);

	if (ret) {

		ublk_err("ublk dev %d thread %u init failed\n",

				dev_id, t->idx);

		return NULL;

	}

	/* IO perf is sensitive with queue pthread affinity on NUMA machine*/

	if (info->affinity)

		ublk_thread_set_sched_affinity(t, info->affinity);

	sem_post(info->ready);



	ublk_dbg(UBLK_DBG_THREAD, "tid %d: ublk dev %d thread %u started\n",