Commit 23e77b5d authored by David Hildenbrand's avatar David Hildenbrand Committed by Michael S. Tsirkin
Browse files

virtio-mem: Better retry handling 



Let's start with a retry interval of 5 seconds and double the time until
we reach 5 minutes, in case we keep getting errors. Reset the retry
interval in case we succeeded.

The two main reasons for having to retry are
- The hypervisor is busy and cannot process our request
- We cannot reach the desired requested_size (esp., not enough memory can
  get unplugged because we can't allocate any subblocks).

Tested-by: default avatarPankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200507140139.17083-11-david@redhat.com


Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent a5732387

drivers/virtio/virtio_mem.c

+8 −3
Original line number Diff line number Diff line
@@ -141,7 +141,9 @@ struct virtio_mem { 


	/* Timer for retrying to plug/unplug memory. */

	struct hrtimer retry_timer;

#define VIRTIO_MEM_RETRY_TIMER_MS		30000

	unsigned int retry_timer_ms;

#define VIRTIO_MEM_RETRY_TIMER_MIN_MS		50000

#define VIRTIO_MEM_RETRY_TIMER_MAX_MS		300000



	/* Memory notifier (online/offline events). */

	struct notifier_block memory_notifier;
@@ -1550,6 +1552,7 @@ static void virtio_mem_run_wq(struct work_struct *work) 


	switch (rc) {

	case 0:

		vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;

		break;

	case -ENOSPC:

		/*
@@ -1565,8 +1568,7 @@ static void virtio_mem_run_wq(struct work_struct *work) 
		 */

	case -ENOMEM:

		/* Out of memory, try again later. */

		hrtimer_start(&vm->retry_timer,

			      ms_to_ktime(VIRTIO_MEM_RETRY_TIMER_MS),

		hrtimer_start(&vm->retry_timer, ms_to_ktime(vm->retry_timer_ms),

			      HRTIMER_MODE_REL);

		break;

	case -EAGAIN:
@@ -1586,6 +1588,8 @@ static enum hrtimer_restart virtio_mem_timer_expired(struct hrtimer *timer) 
					     retry_timer);



	virtio_mem_retry(vm);

	vm->retry_timer_ms = min_t(unsigned int, vm->retry_timer_ms * 2,

				   VIRTIO_MEM_RETRY_TIMER_MAX_MS);

	return HRTIMER_NORESTART;

}
@@ -1754,6 +1758,7 @@ static int virtio_mem_probe(struct virtio_device *vdev) 
	spin_lock_init(&vm->removal_lock);

	hrtimer_init(&vm->retry_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);

	vm->retry_timer.function = virtio_mem_timer_expired;

	vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;



	/* register the virtqueue */

	rc = virtio_mem_init_vq(vm);