Re: [RFC 1/3] virtio_balloon: introduce oom-kill invocations

[David Hildenbrand]

On 15.04.24 10:41, zhenwei pi wrote:
> When the guest OS runs under critical memory pressure, the guest
> starts to kill processes. A guest monitor agent may scan 'oom_kill'
> from /proc/vmstat, and reports the OOM KILL event. However, the agent
> may be killed and we will loss this critical event(and the later
> events).
>
> For now we can also grep for magic words in guest kernel log from host
> side. Rather than this unstable way, virtio balloon reports OOM-KILL
> invocations instead.
>
> Signed-off-by: zhenwei pi <pizhenwei@xxxxxxxxxxxxx>
> ---
>   drivers/virtio/virtio_balloon.c     | 2 ++
>   include/uapi/linux/virtio_balloon.h | 6 ++++--
>   2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index 1f5b3dd31fcf..fd8daa742734 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -352,6 +352,8 @@ static unsigned int update_balloon_stats(struct virtio_balloon *vb)
>   				pages_to_bytes(available));
>   	update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHES,
>   				pages_to_bytes(caches));
> +	update_stat(vb, idx++, VIRTIO_BALLOON_S_OOM_KILL,
> +				events[OOM_KILL]);
>   
>   	return idx;
>   }
> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
> index ddaa45e723c4..cde5547e64a7 100644
> --- a/include/uapi/linux/virtio_balloon.h
> +++ b/include/uapi/linux/virtio_balloon.h
> @@ -71,7 +71,8 @@ struct virtio_balloon_config {
>   #define VIRTIO_BALLOON_S_CACHES   7   /* Disk caches */
>   #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_NR       10
> +#define VIRTIO_BALLOON_S_OOM_KILL      10 /* OOM killer invocations */
> +#define VIRTIO_BALLOON_S_NR       11
>   
>   #define VIRTIO_BALLOON_S_NAMES_WITH_PREFIX(VIRTIO_BALLOON_S_NAMES_prefix) { \
>   	VIRTIO_BALLOON_S_NAMES_prefix "swap-in", \
> @@ -83,7 +84,8 @@ struct virtio_balloon_config {
>   	VIRTIO_BALLOON_S_NAMES_prefix "available-memory", \
>   	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 "hugetlb-failures", \
> +	VIRTIO_BALLOON_S_NAMES_prefix "oom-kill" \

"oom-kills"

--
Cheers,

David / dhildenb