On Thu, Sep 21, 2017 at 02:55:41PM +0200, Tomáš Golembiovský wrote:
> Add a new fields, VIRTIO_BALLOON_S_BUFFERS and VIRTIO_BALLOON_S_CACHED,
> to virtio_balloon memory statistics protocol. The values correspond to
> 'Buffers' and 'Cached' in /proc/meminfo.
>
> To be able to compute the value of 'Cached' memory it is necessary to
> export total_swapcache_pages() to modules.
>
> Signed-off-by: Tomáš Golembiovský <tgolembi@xxxxxxxxxx>
Does 'Buffers' actually make sense? It's a temporary storage -
wouldn't it be significantly out of date by the time
host receives it?
> ---
> drivers/virtio/virtio_balloon.c | 11 +++++++++++
> include/uapi/linux/virtio_balloon.h | 4 +++-
> mm/swap_state.c | 1 +
> 3 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index f0b3a0b9d42f..c2558ec47a62 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
> @@ -244,12 +244,19 @@ static unsigned int update_balloon_stats(struct virtio_balloon *vb)
> struct sysinfo i;
> unsigned int idx = 0;
> long available;
> + long cached;
>
> all_vm_events(events);
> si_meminfo(&i);
>
> available = si_mem_available();
>
> + cached = global_node_page_state(NR_FILE_PAGES) -
> + total_swapcache_pages() - i.bufferram;
> + if (cached < 0)
> + cached = 0;
> +
> +
> #ifdef CONFIG_VM_EVENT_COUNTERS
> update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
> pages_to_bytes(events[PSWPIN]));
> @@ -264,6 +271,10 @@ static unsigned int update_balloon_stats(struct virtio_balloon *vb)
> pages_to_bytes(i.totalram));
> update_stat(vb, idx++, VIRTIO_BALLOON_S_AVAIL,
> pages_to_bytes(available));
> + update_stat(vb, idx++, VIRTIO_BALLOON_S_BUFFERS,
> + pages_to_bytes(i.bufferram));
> + update_stat(vb, idx++, VIRTIO_BALLOON_S_CACHED,
> + pages_to_bytes(cached));
>
> return idx;
> }
> diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h
> index 343d7ddefe04..d5dc8a56a497 100644
> --- a/include/uapi/linux/virtio_balloon.h
> +++ b/include/uapi/linux/virtio_balloon.h
> @@ -52,7 +52,9 @@ struct virtio_balloon_config {
> #define VIRTIO_BALLOON_S_MEMFREE 4 /* Total amount of free memory */
> #define VIRTIO_BALLOON_S_MEMTOT 5 /* Total amount of memory */
> #define VIRTIO_BALLOON_S_AVAIL 6 /* Available memory as in /proc */
> -#define VIRTIO_BALLOON_S_NR 7
> +#define VIRTIO_BALLOON_S_BUFFERS 7 /* Buffers memory as in /proc */
> +#define VIRTIO_BALLOON_S_CACHED 8 /* Cached memory as in /proc */
> +#define VIRTIO_BALLOON_S_NR 9
>
> /*
> * Memory statistics structure.
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 71ce2d1ccbf7..f3a4ff7d6c52 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -95,6 +95,7 @@ unsigned long total_swapcache_pages(void)
> rcu_read_unlock();
> return ret;
> }
> +EXPORT_SYMBOL_GPL(total_swapcache_pages);
>
> static atomic_t swapin_readahead_hits = ATOMIC_INIT(4);
Need an ack from MM crowd on that.
> --
> 2.14.1
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