From 60aabb9a5b090ceb71d1bfc90ecd2c5f66138f69 Mon Sep 17 00:00:00 2001 From: Yogesh Lal Date: Wed, 24 Mar 2021 16:31:38 +0530 Subject: [PATCH] FROMGIT: driver core: Use unbound workqueue for deferred probes Deferred probe usually runs only on pinned kworkers, which might take longer time if a device contains multiple sub-devices. One such case is of sound card on mobile devices, where we have good number of mixers and controls per mixer. We observed boot up improvement - deferred probes take ~600ms when bound to little core kworker and ~200ms when deferred probe is queued on unbound wq. This is due to scheduler moving the worker running deferred probe work to big CPUs. Without this change, we see the worker is running on LITTLE CPU due to affinity. Since kworker runs deferred probe of several devices, the locality may not be important. Also, init thread executing driver initcalls, can potentially migrate as it has cpu affinity set to all cpus.In addition to this, async probes use unbounded workqueue. So, using unbounded wq for deferred probes looks to be similar to these w.r.t. scheduling behavior. Bug: 184491346 Signed-off-by: Yogesh Lal (cherry picked from commit e611f8cd8717c8fe7d4229997e6cd029a1465253 git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git driver-core-next) Link: https://lore.kernel.org/r/1616583698-6398-1-git-send-email-ylal@codeaurora.org Signed-off-by: Greg Kroah-Hartman Change-Id: I4ab97d56a35fdd8c51386aa18e45655ce5360846 Signed-off-by: Mukesh Ojha --- drivers/base/dd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 3c94ebc8d4bb..808933c562e9 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -182,7 +182,7 @@ static void driver_deferred_probe_trigger(void) * Kick the re-probe thread. It may already be scheduled, but it is * safe to kick it again. */ - schedule_work(&deferred_probe_work); + queue_work(system_unbound_wq, &deferred_probe_work); } /**