There are cases that users want to shrink balloon pages after the
pagecache depleted. The conservative_shrinker lets the shrinker
shrink balloon pages when all the pagecache has been reclaimed.
Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx>
---
drivers/virtio/virtio_balloon.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 93f995f6cf36..b4c5bb13a867 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -42,6 +42,10 @@
static struct vfsmount *balloon_mnt;
#endif
+static bool conservative_shrinker = true;
+module_param(conservative_shrinker, bool, 0644);
+MODULE_PARM_DESC(conservative_shrinker, "conservatively shrink balloon pages");
+
enum virtio_balloon_vq {
VIRTIO_BALLOON_VQ_INFLATE,
VIRTIO_BALLOON_VQ_DEFLATE,
@@ -796,6 +800,10 @@ static unsigned long shrink_balloon_pages(struct virtio_balloon *vb,
{
unsigned long pages_freed = 0;
+ /* Balloon pages only gets shrunk when the pagecache depleted */
+ if (conservative_shrinker && global_node_page_state(NR_FILE_PAGES))
+ return 0;
+
/*
* One invocation of leak_balloon can deflate at most
* VIRTIO_BALLOON_ARRAY_PFNS_MAX balloon pages, so we call it
@@ -837,7 +845,11 @@ static unsigned long virtio_balloon_shrinker_count(struct shrinker *shrinker,
struct virtio_balloon, shrinker);
unsigned long count;
- count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE;
+ if (conservative_shrinker && global_node_page_state(NR_FILE_PAGES))
+ count = 0;
+ else
+ count = vb->num_pages / VIRTIO_BALLOON_PAGES_PER_PAGE;
+
count += vb->num_free_page_blocks * VIRTIO_BALLOON_HINT_BLOCK_PAGES;
return count;
--
2.17.1
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