[PATCH v2 3/4] virtio_balloon: introduce memory allocation stall counter

[zhenwei pi]

Memory allocation stall counter represents the performance/latency of
memory allocation, expose this counter to the host side by virtio
balloon device via out-of-bound way.

Signed-off-by: zhenwei pi <pizhen...@bytedance.com>
---
 drivers/virtio/virtio_balloon.c     | 8 ++++++++
 include/uapi/linux/virtio_balloon.h | 6 ++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 87a1d6fa77fb..ab039e83bc6f 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -323,6 +323,8 @@ static inline unsigned int update_balloon_vm_stats(struct 
virtio_balloon *vb,
 #ifdef CONFIG_VM_EVENT_COUNTERS
        unsigned long events[NR_VM_EVENT_ITEMS];
        unsigned int idx = start;
+       unsigned int zid;
+       unsigned long stall = 0;
 
        all_vm_events(events);
        update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
@@ -333,6 +335,12 @@ static inline unsigned int update_balloon_vm_stats(struct 
virtio_balloon *vb,
        update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
        update_stat(vb, idx++, VIRTIO_BALLOON_S_OOM_KILL, events[OOM_KILL]);
 
+       /* sum all the stall events */
+       for (zid = 0; zid < MAX_NR_ZONES; zid++)
+               stall += events[ALLOCSTALL_NORMAL - ZONE_NORMAL + zid];
+
+       update_stat(vb, idx++, VIRTIO_BALLOON_S_ALLOC_STALL, stall);
+
 #ifdef CONFIG_HUGETLB_PAGE
        update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC,
                    events[HTLB_BUDDY_PGALLOC]);
diff --git a/include/uapi/linux/virtio_balloon.h 
b/include/uapi/linux/virtio_balloon.h
index b17bbe033697..487b893a160e 100644
--- a/include/uapi/linux/virtio_balloon.h
+++ b/include/uapi/linux/virtio_balloon.h
@@ -72,7 +72,8 @@ struct virtio_balloon_config {
 #define VIRTIO_BALLOON_S_HTLB_PGALLOC  8  /* Hugetlb page allocations */
 #define VIRTIO_BALLOON_S_HTLB_PGFAIL   9  /* Hugetlb page allocation failures 
*/
 #define VIRTIO_BALLOON_S_OOM_KILL      10 /* OOM killer invocations */
-#define VIRTIO_BALLOON_S_NR       11
+#define VIRTIO_BALLOON_S_ALLOC_STALL   11 /* Stall count of memory allocatoin 
*/
+#define VIRTIO_BALLOON_S_NR       12
 
 #define VIRTIO_BALLOON_S_NAMES_WITH_PREFIX(VIRTIO_BALLOON_S_NAMES_prefix) { \
        VIRTIO_BALLOON_S_NAMES_prefix "swap-in", \
@@ -85,7 +86,8 @@ struct virtio_balloon_config {
        VIRTIO_BALLOON_S_NAMES_prefix "disk-caches", \
        VIRTIO_BALLOON_S_NAMES_prefix "hugetlb-allocations", \
        VIRTIO_BALLOON_S_NAMES_prefix "hugetlb-failures", \
-       VIRTIO_BALLOON_S_NAMES_prefix "oom-kills" \
+       VIRTIO_BALLOON_S_NAMES_prefix "oom-kills", \
+       VIRTIO_BALLOON_S_NAMES_prefix "alloc-stalls" \
 }
 
 #define VIRTIO_BALLOON_S_NAMES VIRTIO_BALLOON_S_NAMES_WITH_PREFIX("")
-- 
2.34.1