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* [PATCH AUTOSEL 5.10 01/17] workqueue: Kick a worker based on the actual activation of delayed works
@ 2021-01-05  0:58 Sasha Levin
  2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 02/17] scsi: ufs: Fix wrong print message in dev_err() Sasha Levin
                   ` (15 more replies)
  0 siblings, 16 replies; 17+ messages in thread
From: Sasha Levin @ 2021-01-05  0:58 UTC (permalink / raw)
  To: linux-kernel, stable; +Cc: Yunfeng Ye, Lai Jiangshan, Tejun Heo, Sasha Levin

From: Yunfeng Ye <yeyunfeng@huawei.com>

[ Upstream commit 01341fbd0d8d4e717fc1231cdffe00343088ce0b ]

In realtime scenario, We do not want to have interference on the
isolated cpu cores. but when invoking alloc_workqueue() for percpu wq
on the housekeeping cpu, it kick a kworker on the isolated cpu.

  alloc_workqueue
    pwq_adjust_max_active
      wake_up_worker

The comment in pwq_adjust_max_active() said:
  "Need to kick a worker after thawed or an unbound wq's
   max_active is bumped"

So it is unnecessary to kick a kworker for percpu's wq when invoking
alloc_workqueue(). this patch only kick a worker based on the actual
activation of delayed works.

Signed-off-by: Yunfeng Ye <yeyunfeng@huawei.com>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/workqueue.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 437935e7a1991..0695c7895c892 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3728,17 +3728,24 @@ 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;
 	}
-- 
2.27.0


^ permalink raw reply related	[flat|nested] 17+ messages in thread
end of thread, other threads:[~2021-01-05  1:07 UTC | newest]

Thread overview: 17+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-01-05  0:58 [PATCH AUTOSEL 5.10 01/17] workqueue: Kick a worker based on the actual activation of delayed works Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 02/17] scsi: ufs: Fix wrong print message in dev_err() Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 03/17] scsi: ufs: Clear UAC for RPMB after ufshcd resets Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 04/17] scsi: ufs-pci: Fix restore from S4 for Intel controllers Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 05/17] scsi: ufs-pci: Ensure UFS device is in PowerDown mode for suspend-to-disk ->poweroff() Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 06/17] scsi: ufs-pci: Fix recovery from hibernate exit errors for Intel controllers Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 07/17] scsi: ufs-pci: Enable UFSHCD_CAP_RPM_AUTOSUSPEND " Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 08/17] scsi: block: Introduce BLK_MQ_REQ_PM Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 09/17] scsi: ide: Do not set the RQF_PREEMPT flag for sense requests Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 10/17] scsi: ide: Mark power management requests with RQF_PM instead of RQF_PREEMPT Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 11/17] scsi: scsi_transport_spi: Set RQF_PM for domain validation commands Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 12/17] scsi: core: Only process PM requests if rpm_status != RPM_ACTIVE Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 13/17] local64.h: make <asm/local64.h> mandatory Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 14/17] kdev_t: always inline major/minor helper functions Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 15/17] lib/genalloc: fix the overflow when size is too big Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 16/17] depmod: handle the case of /sbin/depmod without /sbin in PATH Sasha Levin
2021-01-05  0:59 ` [PATCH AUTOSEL 5.10 17/17] scsi: ufs: Clear UAC for FFU and RPMB LUNs Sasha Levin

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