Re: [PATCH 1/1] balloon: introduce 6 memory statistics

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, May 13, 2024 at 08:10:05PM +0800, zhenwei pi wrote:
> Expose more memory statistics of the virtual memory subsystem from
> guest, it's helpful to analyze the memory performance and pressure
> from host side.
> 
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> ---
>  device-types/balloon/description.tex | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/device-types/balloon/description.tex b/device-types/balloon/description.tex
> index a1d9603..bc8e109 100644
> --- a/device-types/balloon/description.tex
> +++ b/device-types/balloon/description.tex
> @@ -305,6 +305,12 @@ \subsubsection{Memory Statistics}\label{sec:Device Types / Memory Balloon Device
>  #define VIRTIO_BALLOON_S_CACHES   7
>  #define VIRTIO_BALLOON_S_HTLB_PGALLOC 8
>  #define VIRTIO_BALLOON_S_HTLB_PGFAIL  9
> +#define VIRTIO_BALLOON_S_OOM_KILL       10
> +#define VIRTIO_BALLOON_S_ALLOC_STALL    11
> +#define VIRTIO_BALLOON_S_ASYNC_SCAN     12
> +#define VIRTIO_BALLOON_S_DIRECT_SCAN    13
> +#define VIRTIO_BALLOON_S_ASYNC_RECLAIM  14
> +#define VIRTIO_BALLOON_S_DIRECT_RECLAIM 15
>          le16 tag;
>          le64 val;
>  } __attribute__((packed));
> @@ -399,6 +405,24 @@ \subsubsection{Memory Statistics Tags}\label{sec:Device Types / Memory Balloon D
>  
>  \item[VIRTIO_BALLOON_S_HTLB_PGFAIL (9)] The number of failed hugetlb page
>    allocations in the guest.


Would it make sense to reference
https://docs.kernel.org/admin-guide/mm/concepts.html ?
you seem to be using terminology from there.
And then pls actually use terminology from there.


> +
> +\item[VIRTIO_BALLOON_S_OOM_KILL (10)] The number of Out-Of-Memory killer
> +  invocations.


What exactly are "invocations"? The number of times a task was killed
to free memory?

> +
> +\item[VIRTIO_BALLOON_S_ALLOC_STALL (11)] The number of stall count on memory
> +  allocation.
>

count and number is mostly the same.

Again what is this counting? pages? stalls? If stalls isn't this always
the same as direct reclaim?

> +\item[VIRTIO_BALLOON_S_ASYNC_SCAN (12)] The amount of memory that has been
> +  scanned asynchronously (in bytes).

scanned by what? which memory do you count as "scanned"?

> +
> +\item[VIRTIO_BALLOON_S_DIRECT_SCAN (13)] The amount of memory that has been
> +  scanned directly (in bytes).

what is "scanned directly"?


> +
> +\item[VIRTIO_BALLOON_S_ASYNC_RECLAIM (14)] The amount of memory that has been
> +  reclaimed asynchronously (in bytes).

again reclaimed by what? free? evict?

> +
> +\item[VIRTIO_BALLOON_S_DIRECT_RECLAIM (15)] The amount of memory that has been
> +  reclaimed directly (in bytes).
>  \end{description}
>  
>  \subsubsection{Free Page Hinting}\label{sec:Device Types / Memory Balloon Device / Device Operation / Free Page Hinting}
> -- 
> 2.34.1
>