Merge branch 'for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue update from Tejun Heo:
 "The same as the cgroup tree - one commit which was scheduled for the
  5.11 merge window.

  All the commit does is avoding spurious worker wakeups from workqueue
  allocation / config change path to help cpuisol use cases"

* 'for-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: Kick a worker based on the actual activation of delayed works

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index b5295a0..9880b6c 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3731,17 +3731,24 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq)
         * is updated and visible.
         */
        if (!freezable || !workqueue_freezing) {
+               bool kick = false;
+
                pwq->max_active = wq->saved_max_active;
 
                while (!list_empty(&pwq->delayed_works) &&
-                      pwq->nr_active < pwq->max_active)
+                      pwq->nr_active < pwq->max_active) {
                        pwq_activate_first_delayed(pwq);
+                       kick = true;
+               }
 
                /*
                 * Need to kick a worker after thawed or an unbound wq's
-                * max_active is bumped.  It's a slow path.  Do it always.
+                * max_active is bumped. In realtime scenarios, always kicking a
+                * worker will cause interference on the isolated cpu cores, so
+                * let's kick iff work items were activated.
                 */
-               wake_up_worker(pwq->pool);
+               if (kick)
+                       wake_up_worker(pwq->pool);
        } else {
                pwq->max_active = 0;
        }