search for: system_freezable_wq

Hello, Michael, Petr. On Wed, Nov 12, 2014 at 03:32:04PM +0200, Michael S. Tsirkin wrote: > > + /* The workqueue servicing the balloon. */ > > + struct workqueue_struct *wq; > > + struct work_struct wq_work; > > We could use system_freezable_wq instead. > I do agree a dedicated wq is better since this can get blocked > for a long time while allocating memory. > However, please add a comment to this effect. system_freezable_wq should be fine. Workqueues by default have a pretty high maximum concurrency level (256). There's...

Hello, Michael, Petr. On Wed, Nov 12, 2014 at 03:32:04PM +0200, Michael S. Tsirkin wrote: > > + /* The workqueue servicing the balloon. */ > > + struct workqueue_struct *wq; > > + struct work_struct wq_work; > > We could use system_freezable_wq instead. > I do agree a dedicated wq is better since this can get blocked > for a long time while allocating memory. > However, please add a comment to this effect. system_freezable_wq should be fine. Workqueues by default have a pretty high maximum concurrency level (256). There's...

...n removing the balloon + do not queue the work from fill_balloon() and leak_balloon() because they are called also independently from the workqueue, e.g. remove_common(), virtballoon_oom_notify(). Re-queue the work from the work function when necessary. Changes against v2: + Use system_freezable_wq instead of an allocated one and move INIT_WORK() higher in virtballoon_probe(). + Fix typos in the commit message. Changes against v1: + More elegant detection of the pending work in fill_balloon() and leak_balloon(). It still needs to keep the original requested number of pages...

...n removing the balloon + do not queue the work from fill_balloon() and leak_balloon() because they are called also independently from the workqueue, e.g. remove_common(), virtballoon_oom_notify(). Re-queue the work from the work function when necessary. Changes against v2: + Use system_freezable_wq instead of an allocated one and move INIT_WORK() higher in virtballoon_probe(). + Fix typos in the commit message. Changes against v1: + More elegant detection of the pending work in fill_balloon() and leak_balloon(). It still needs to keep the original requested number of pages...

...instead. Tejun Heo confirmed that the system workqueue has a pretty high concurrency level (256) by default. Therefore we need not be afraid of too long blocking. Signed-off-by: Petr Mladek <pmladek at suse.cz> Acked-by: Michael S. Tsirkin <mst at redhat.com> --- Changes in v3: + Use system_freezable_wq instead of an allocated one and move INIT_WORK() higher in virtballoon_probe(). + Fix typos in the commit message. Changes in v2: + More elegant detection of the pending work in fill_balloon() and leak_balloon(). It still needs to keep the original requested number of pages but it doe...

...instead. Tejun Heo confirmed that the system workqueue has a pretty high concurrency level (256) by default. Therefore we need not be afraid of too long blocking. Signed-off-by: Petr Mladek <pmladek at suse.cz> Acked-by: Michael S. Tsirkin <mst at redhat.com> --- Changes in v3: + Use system_freezable_wq instead of an allocated one and move INIT_WORK() higher in virtballoon_probe(). + Fix typos in the commit message. Changes in v2: + More elegant detection of the pending work in fill_balloon() and leak_balloon(). It still needs to keep the original requested number of pages but it doe...

...m using CentOS 7 where qemu does not recognize deflate-on-oom option. ;-) > OK. Or if you use my patch, you can just set a flag and go > if (vb->oom) > msleep(1000); > at beginning of fill_balloon. I don't think it is a good manner to sleep for long from the point of view of system_freezable_wq, for system_freezable_wq is expected to flush shortly according to include/linux/workqueue.h . I think that using delayed_work is better. > > While response was better than now, inflating again spoiled the effort. > > Retrying to inflate until allocation fails is already too painful. &...

...m using CentOS 7 where qemu does not recognize deflate-on-oom option. ;-) > OK. Or if you use my patch, you can just set a flag and go > if (vb->oom) > msleep(1000); > at beginning of fill_balloon. I don't think it is a good manner to sleep for long from the point of view of system_freezable_wq, for system_freezable_wq is expected to flush shortly according to include/linux/workqueue.h . I think that using delayed_work is better. > > While response was better than now, inflating again spoiled the effort. > > Retrying to inflate until allocation fails is already too painful. &...

...n removing the balloon + do not queue the work from fill_balloon() and leak_balloon() because they are called also independently from the workqueue, e.g. remove_common(), virtballoon_oom_notify(). Re-queue the work from the work function when necessary. Changes against v2: + Use system_freezable_wq instead of an allocated one and move INIT_WORK() higher in virtballoon_probe(). + Fix typos in the commit message. Changes against v1: + More elegant detection of the pending work in fill_balloon() and leak_balloon(). It still needs to keep the original requested number of pages...

...n removing the balloon + do not queue the work from fill_balloon() and leak_balloon() because they are called also independently from the workqueue, e.g. remove_common(), virtballoon_oom_notify(). Re-queue the work from the work function when necessary. Changes against v2: + Use system_freezable_wq instead of an allocated one and move INIT_WORK() higher in virtballoon_probe(). + Fix typos in the commit message. Changes against v1: + More elegant detection of the pending work in fill_balloon() and leak_balloon(). It still needs to keep the original requested number of pages...

...y. */ - msleep(200); + *delay = HZ / 5; break; } set_page_pfns(vb, vb->pfns + vb->num_pfns, page); @@ -310,7 +319,8 @@ static void virtballoon_changed(struct virtio_device *vdev) spin_lock_irqsave(&vb->stop_update_lock, flags); if (!vb->stop_update) - queue_work(system_freezable_wq, &vb->update_balloon_size_work); + queue_delayed_work(system_freezable_wq, + &vb->update_balloon_size_work, 0); spin_unlock_irqrestore(&vb->stop_update_lock, flags); } @@ -366,9 +376,13 @@ static int virtballoon_oom_notify(struct notifier_block *self, if (virtio_h...

...y. */ - msleep(200); + *delay = HZ / 5; break; } set_page_pfns(vb, vb->pfns + vb->num_pfns, page); @@ -310,7 +319,8 @@ static void virtballoon_changed(struct virtio_device *vdev) spin_lock_irqsave(&vb->stop_update_lock, flags); if (!vb->stop_update) - queue_work(system_freezable_wq, &vb->update_balloon_size_work); + queue_delayed_work(system_freezable_wq, + &vb->update_balloon_size_work, 0); spin_unlock_irqrestore(&vb->stop_update_lock, flags); } @@ -366,9 +376,13 @@ static int virtballoon_oom_notify(struct notifier_block *self, if (virtio_h...

...nged(struct virtio_device *vdev) > { > struct virtio_balloon *vb = vdev->priv; > unsigned long flags; > - s64 diff = towards_target(vb); > - > - if (diff) { > - spin_lock_irqsave(&vb->stop_update_lock, flags); > - if (!vb->stop_update) > - queue_work(system_freezable_wq, > - &vb->update_balloon_size_work); > - spin_unlock_irqrestore(&vb->stop_update_lock, flags); > - } > > - if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > - virtio_cread(vdev, struct virtio_balloon_config, > - free_page_report_c...

Since virtio-ccw doesn't work with accessing to the config registers inside an interrupt context, this patch series avoids that issue by moving the config register accesses to the related workqueue contexts. Wei Wang (2): virtio-balloon: tweak config_changed implementation virtio-balloon: improve update_balloon_size_func drivers/virtio/virtio_balloon.c | 59

...we delegate the job to a freezable workqueue that will do the actual work via + * stats_handle_request(). */ static void stats_request(struct virtqueue *vq) { struct virtio_balloon *vb = vq->vdev->priv; vb->need_stats_update = 1; - wake_up(&vb->config_change); + queue_work(system_freezable_wq, &vb->wq_work); } static void stats_handle_request(struct virtio_balloon *vb) @@ -286,7 +283,7 @@ static void virtballoon_changed(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; - wake_up(&vb->config_change); + queue_work(system_freezable_wq, &vb-...

...e_kick(vq); > } > > -static void virtballoon_changed(struct virtio_device *vdev) > -{ > - struct virtio_balloon *vb = vdev->priv; > - unsigned long flags; > - > - spin_lock_irqsave(&vb->stop_update_lock, flags); > - if (!vb->stop_update) > - queue_work(system_freezable_wq, &vb->update_balloon_size_work); > - spin_unlock_irqrestore(&vb->stop_update_lock, flags); > -} > - > static inline s64 towards_target(struct virtio_balloon *vb) > { > s64 target; > @@ -353,6 +369,35 @@ static inline s64 towards_target(struct virtio_balloon *v...

...e_kick(vq); > } > > -static void virtballoon_changed(struct virtio_device *vdev) > -{ > - struct virtio_balloon *vb = vdev->priv; > - unsigned long flags; > - > - spin_lock_irqsave(&vb->stop_update_lock, flags); > - if (!vb->stop_update) > - queue_work(system_freezable_wq, &vb->update_balloon_size_work); > - spin_unlock_irqrestore(&vb->stop_update_lock, flags); > -} > - > static inline s64 towards_target(struct virtio_balloon *vb) > { > s64 target; > @@ -353,6 +369,35 @@ static inline s64 towards_target(struct virtio_balloon *v...

Since virtio-ccw doesn't work with accessing to the config space inside an interrupt context, this patch series avoids that issue by moving the config register accesses to the related workqueue contexts. v1->v2 ChangeLog: - add config_read_bitmap to indicate to the workqueue callbacks about the necessity of reading the related config fields. Wei Wang (2): virtio-balloon: tweak

...394,33 +394,15 @@ static void virtballoon_changed(struct virtio_device *vdev) { struct virtio_balloon *vb = vdev->priv; unsigned long flags; - s64 diff = towards_target(vb); - - if (diff) { - spin_lock_irqsave(&vb->stop_update_lock, flags); - if (!vb->stop_update) - queue_work(system_freezable_wq, - &vb->update_balloon_size_work); - spin_unlock_irqrestore(&vb->stop_update_lock, flags); - } - if (virtio_has_feature(vdev, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { - virtio_cread(vdev, struct virtio_balloon_config, - free_page_report_cmd_id, &vb->cmd_id_received)...

...5; > break; > } > set_page_pfns(vb, vb->pfns + vb->num_pfns, page); > @@ -310,7 +319,8 @@ static void virtballoon_changed(struct virtio_device *vdev) > > spin_lock_irqsave(&vb->stop_update_lock, flags); > if (!vb->stop_update) > - queue_work(system_freezable_wq, &vb->update_balloon_size_work); > + queue_delayed_work(system_freezable_wq, > + &vb->update_balloon_size_work, 0); > spin_unlock_irqrestore(&vb->stop_update_lock, flags); > } > > @@ -366,9 +376,13 @@ static int virtballoon_oom_notify(struct notifi...