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: Pankaj 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: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20200507140139.17083-11-david@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
David Hildenbrand 2020-05-07 16:01:34 +02:00 committed by Michael S. Tsirkin
parent a573238786
commit 23e77b5dc9

View file

@ -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);