Start dropping slab objects after 30 minutes and repeat every 30 minutes in case we can't unplug more memory using alloc_contig_range(). Log messages and make it configurable. Enable dropping slab objects as default (especially, reclaimable slab objects that are not movable).
In the future, we might want to implement+use drop_slab_range(), which will also come in handy for other users (e.g., offlining, gigantic huge pages). Cc: Alexander Viro <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Michal Hocko <[email protected]> Cc: "Michael S. Tsirkin" <[email protected]> Cc: Jason Wang <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Igor Mammedov <[email protected]> Cc: Dave Young <[email protected]> Cc: Dan Williams <[email protected]> Cc: Pavel Tatashin <[email protected]> Cc: Stefan Hajnoczi <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: [email protected] Signed-off-by: David Hildenbrand <[email protected]> --- drivers/virtio/virtio_mem.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 3a57434f92ed..8f25f7453a08 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -25,6 +25,11 @@ static bool unplug_online = true; module_param(unplug_online, bool, 0644); MODULE_PARM_DESC(unplug_online, "Try to unplug online memory"); +static bool drop_slab_objects = true; +module_param(drop_slab_objects, bool, 0644); +MODULE_PARM_DESC(drop_slab_objects, + "Drop slab objects when unplug continues to fail"); + enum virtio_mem_mb_state { /* Unplugged, not added to Linux. Can be reused later. */ VIRTIO_MEM_MB_STATE_UNUSED = 0, @@ -1384,6 +1389,7 @@ static int virtio_mem_mb_unplug_any_sb_online(struct virtio_mem *vm, static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff) { uint64_t nb_sb = diff / vm->subblock_size; + bool retried = false; unsigned long mb_id; int rc; @@ -1421,6 +1427,7 @@ static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff) return 0; } +retry_locked: /* Try to unplug subblocks of partially plugged online blocks. */ virtio_mem_for_each_mb_state(vm, mb_id, VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL) { @@ -1445,6 +1452,29 @@ static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff) } mutex_unlock(&vm->hotplug_mutex); + + /* + * If we can't unplug the requested amount of memory for a long time, + * start freeing up memory in caches. This might harm performance, + * is configurable, and we log a message. Retry imemdiately a second + * time - then wait another VIRTIO_MEM_RETRY_TIMER_MAX_MS. + */ + if (nb_sb && !retried && drop_slab_objects && + vm->retry_timer_ms == VIRTIO_MEM_RETRY_TIMER_MAX_MS) { + if (vm->nid == NUMA_NO_NODE) { + dev_info(&vm->vdev->dev, "dropping all slab objects\n"); + drop_slab(); + } else { + dev_info(&vm->vdev->dev, + "dropping all slab objects on node=%d\n", + vm->nid); + drop_slab_node(vm->nid); + } + retried = true; + mutex_lock(&vm->hotplug_mutex); + goto retry_locked; + } + return nb_sb ? -EBUSY : 0; out_unlock: mutex_unlock(&vm->hotplug_mutex); -- 2.23.0 _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
