Re: [PATCH 1/3] Track additional Cache stats

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 19/07/2021 11:03, Owen Smith wrote:
> Track Current/Maximum number of slabs, and Current/Maximum number of objects in
> use.
>
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
Acked-by: Paul Durrant <paul@xxxxxxx>

> ---
>   src/xenbus/cache.c | 36 ++++++++++++++++++++++++++++++++++--
>   1 file changed, 34 insertions(+), 2 deletions(-)
>
> diff --git a/src/xenbus/cache.c b/src/xenbus/cache.c
> index 48772d4..247f244 100644
> --- a/src/xenbus/cache.c
> +++ b/src/xenbus/cache.c
> @@ -88,6 +88,10 @@ struct _XENBUS_CACHE {
>       ULONG                   Count;
>       PXENBUS_CACHE_MAGAZINE  Magazine;
>       ULONG                   MagazineCount;
> +    LONG                    CurrentSlabs;
> +    LONG                    MaximumSlabs;
> +    LONG                    CurrentObjects;
> +    LONG                    MaximumObjects;
>   };
>   
>   struct _XENBUS_CACHE_CONTEXT {
> @@ -296,6 +300,7 @@ CacheCreateSlab(
>       ULONG               Count;
>       ULONG               Size;
>       LONG                Index;
> +    LONG                SlabCount;
>       NTSTATUS            status;
>   
>       NumberOfBytes = P2ROUNDUP(FIELD_OFFSET(XENBUS_CACHE_SLAB, Buffer) +
> @@ -340,6 +345,10 @@ CacheCreateSlab(
>       CacheInsertSlab(Cache, Slab);
>       Cache->Count += Count;
>   
> +    SlabCount = InterlockedIncrement(&Cache->CurrentSlabs);
> +    if (SlabCount > Cache->MaximumSlabs)
> +        Cache->MaximumSlabs = SlabCount;
> +
>       return STATUS_SUCCESS;
>   
>   fail4:
> @@ -400,6 +409,9 @@ CacheDestroySlab(
>           __CacheDtor(Cache, Object);
>       }
>   
> +    ASSERT(Cache->CurrentSlabs != 0);
> +    InterlockedDecrement(&Cache->CurrentSlabs);
> +
>       __CacheFree(Slab->Mask);
>       __CacheFree(Slab);
>   }
> @@ -527,6 +539,7 @@ CacheGet(
>       ULONG                   Index;
>       PXENBUS_CACHE_MAGAZINE  Magazine;
>       PVOID                   Object;
> +    LONG                    ObjectCount;
>   
>       UNREFERENCED_PARAMETER(Interface);
>   
> @@ -575,6 +588,12 @@ again:
>           __CacheReleaseLock(Cache);
>   
>   done:
> +    if (Object != NULL) {
> +        ObjectCount = InterlockedIncrement(&Cache->CurrentObjects);
> +        if (ObjectCount > Cache->MaximumObjects)
> +            Cache->MaximumObjects = ObjectCount;
> +    }
> +
>       KeLowerIrql(Irql);
>   
>       return Object;
> @@ -625,6 +644,9 @@ CachePut(
>           __CacheReleaseLock(Cache);
>   
>   done:
> +    ASSERT(Cache->CurrentObjects != 0);
> +    InterlockedDecrement(&Cache->CurrentObjects);
> +
>       KeLowerIrql(Irql);
>   }
>   
> @@ -895,6 +917,12 @@ CacheDestroy(
>   
>       CacheSpill(Cache, 0);
>   
> +    ASSERT(Cache->CurrentObjects == 0);
> +    Cache->MaximumObjects = 0;
> +
> +    ASSERT(Cache->CurrentSlabs == 0);
> +    Cache->MaximumSlabs = 0;
> +
>       Cache->Cursor = NULL;
>       ASSERT(IsListEmpty(&Cache->SlabList));
>       RtlZeroMemory(&Cache->SlabList, sizeof (LIST_ENTRY));
> @@ -942,10 +970,14 @@ CacheDebugCallback(
>   
>               XENBUS_DEBUG(Printf,
>                            &Context->DebugInterface,
> -                         "- %s: Count = %d (Reservation = %d)\n",
> +                         "- %s: Count = %d, Reservation = %d, Objects = %d / %d, 
> Slabs = %d / %d\n",
>                            Cache->Name,
>                            Cache->Count,
> -                         Cache->Reservation);
> +                         Cache->Reservation,
> +                         Cache->CurrentObjects,
> +                         Cache->MaximumObjects,
> +                         Cache->CurrentSlabs,
> +                         Cache->MaximumSlabs);
>           }
>       }
>   }