# \[PATCH\] fbdev: Remove deprecated create\_singlethread\_workqueue - Subsystems: FRAMEBUFFER LAYER, OMAP FRAMEBUFFER SUPPORT, THE REST - Maintainers: Helge Deller, Linus Torvalds - List: linux-fbdev - 3 messages, 3 authors - Page: https://ratatoskr.run/linux-fbdev/2016/07/4787282/t ## \[PATCH\] fbdev: Remove deprecated create\_singlethread\_workqueue - From: Bhaktipriya Shridhar \ - Date: 2016-07-02 08:39:31 - Message: https://ratatoskr.run/linux-fbdev/2016/07/4787282.md ```text The workqueue "esd_wq" has only a single workitem(&md->esd_work) and hence doesn't require ordering. Also, it is not being used on a memory reclaim path. Hence, the singlethreaded workqueue has been replaced with the use of system_wq. System workqueues have been able to handle high level of concurrency for a long time now and hence it's not required to have a singlethreaded workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue created with create_singlethread_workqueue(), system_wq allows multiple work items to overlap executions even on the same CPU; however, a per-cpu workqueue doesn't have any CPU locality or global ordering guarantee unless the target CPU is explicitly specified and thus the increase of local concurrency shouldn't make any difference. mipid_esd_stop_check () calls cancel_delayed_work() in mipid_cleanup() to ensure that there are no pending tasks while disconnecting the driver. Signed-off-by: Bhaktipriya Shridhar --- drivers/video/fbdev/omap/lcd_mipid.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-) diff --git a/drivers/video/fbdev/omap/lcd_mipid.c b/drivers/video/fbdev/omap/lcd_mipid.c index 0e4cee9..c81f150 100644 --- a/drivers/video/fbdev/omap/lcd_mipid.c +++ b/drivers/video/fbdev/omap/lcd_mipid.c @@ -60,7 +60,6 @@ struct mipid_device { struct mutex mutex; struct lcd_panel panel; - struct workqueue_struct *esd_wq; struct delayed_work esd_work; void (*esd_check)(struct mipid_device *m); }; @@ -390,7 +389,7 @@ static void ls041y3_esd_check(struct mipid_device *md) static void mipid_esd_start_check(struct mipid_device *md) { if (md->esd_check != NULL) - queue_delayed_work(md->esd_wq, &md->esd_work, + schedule_delayed_work(&md->esd_work, MIPID_ESD_CHECK_PERIOD); } @@ -476,11 +475,6 @@ static int mipid_init(struct lcd_panel *panel, struct mipid_device *md = to_mipid_device(panel); md->fbdev = fbdev; - md->esd_wq = create_singlethread_workqueue("mipid_esd"); - if (md->esd_wq = NULL) { - dev_err(&md->spi->dev, "can't create ESD workqueue\n"); - return -ENOMEM; - } INIT_DELAYED_WORK(&md->esd_work, mipid_esd_work); mutex_init(&md->mutex); @@ -500,7 +494,6 @@ static void mipid_cleanup(struct lcd_panel *panel) if (md->enabled) mipid_esd_stop_check(md); - destroy_workqueue(md->esd_wq); } static struct lcd_panel mipid_panel = { -- 2.1.4 ``` ## Re: \[PATCH\] fbdev: Remove deprecated create\_singlethread\_workqueue - From: Tejun Heo \ - Date: 2016-07-02 11:36:39 - Message: https://ratatoskr.run/linux-fbdev/2016/07/4787340.md ```text On Sat, Jul 02, 2016 at 02:09:23PM +0530, Bhaktipriya Shridhar wrote: > The workqueue "esd_wq" has only a single workitem(&md->esd_work) > and hence doesn't require ordering. Also, it is not being used on a > memory reclaim path. Hence, the singlethreaded workqueue has been > replaced with the use of system_wq. > > System workqueues have been able to handle high level of concurrency > for a long time now and hence it's not required to have a singlethreaded > workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue > created with create_singlethread_workqueue(), system_wq allows multiple > work items to overlap executions even on the same CPU; however, a > per-cpu workqueue doesn't have any CPU locality or global ordering > guarantee unless the target CPU is explicitly specified and thus the > increase of local concurrency shouldn't make any difference. > > mipid_esd_stop_check () calls cancel_delayed_work() in mipid_cleanup() > to ensure that there are no pending tasks while disconnecting the driver. > > Signed-off-by: Bhaktipriya Shridhar Acked-by: Tejun Heo Thanks. -- tejun ``` ## Re: \[PATCH\] fbdev: Remove deprecated create\_singlethread\_workqueue - From: Tomi Valkeinen \ - Date: 2016-08-10 19:10:34 - Message: https://ratatoskr.run/linux-fbdev/2016/08/4811430.md ```text On 02/07/16 11:39, Bhaktipriya Shridhar wrote: > The workqueue "esd_wq" has only a single workitem(&md->esd_work) > and hence doesn't require ordering. Also, it is not being used on a > memory reclaim path. Hence, the singlethreaded workqueue has been > replaced with the use of system_wq. > > System workqueues have been able to handle high level of concurrency > for a long time now and hence it's not required to have a singlethreaded > workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue > created with create_singlethread_workqueue(), system_wq allows multiple > work items to overlap executions even on the same CPU; however, a > per-cpu workqueue doesn't have any CPU locality or global ordering > guarantee unless the target CPU is explicitly specified and thus the > increase of local concurrency shouldn't make any difference. > > mipid_esd_stop_check () calls cancel_delayed_work() in mipid_cleanup() > to ensure that there are no pending tasks while disconnecting the driver. > > Signed-off-by: Bhaktipriya Shridhar > --- > drivers/video/fbdev/omap/lcd_mipid.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) Thanks, queued for v4.9. Tomi ```