Re: [win-pv-devel] [PATCH 03/10] Store maximum number of queues allowed

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Owen Smith [mailto:owen.smith@xxxxxxxxxx]
> Sent: 12 November 2014 16:39
> To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Paul Durrant; Owen Smith
> Subject: [PATCH 03/10] Store maximum number of queues allowed
> 
> Read "MultiQueueMaxQueues" from parameters key to determine in-guest
> limit to multi-queue support.
> The maximum number of queues used will be the smallest of;
> 
> "HKLM/CurrentControlSet/Services/XENVIF/Parameters/MultiQueueMaxQu
> eues",
>   "device/vif/<number>/multi-queue-max-queues" and
>   number of guest vCPUs
> 
> Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
> ---
>  src/xenvif/driver.c | 36 ++++++++++++++++++++++++++++++++++++
>  src/xenvif/driver.h |  5 +++++
>  2 files changed, 41 insertions(+)
> 
> diff --git a/src/xenvif/driver.c b/src/xenvif/driver.c
> index 6f81620..b1fbb79 100644
> --- a/src/xenvif/driver.c
> +++ b/src/xenvif/driver.c
> @@ -47,6 +47,7 @@ typedef struct _XENVIF_DRIVER {
>      PDRIVER_OBJECT      DriverObject;
>      HANDLE              ParametersKey;
>      HANDLE              AddressesKey;
> +    ULONG               QueueMax;

Is this the index of the last queue or the maximum number of queues? The name 
should be clearer.

>  } XENVIF_DRIVER, *PXENVIF_DRIVER;
> 
>  static XENVIF_DRIVER    Driver;
> @@ -123,6 +124,33 @@ DriverGetAddressesKey(
>      return __DriverGetAddressesKey();
>  }
> 
> +static FORCEINLINE VOID
> +__DriverSetQueueMax(
> +    IN  ULONG       Count
> +    )
> +{
> +    ULONG   Processors;
> +
> +    Processors = KeQueryActiveProcessorCount(NULL);
> +    Driver.QueueMax = Count > Processors ? Processors : Count;

No. This function should a simple setting function. Do the query for actual 
number of processors in the caller.

> +}
> +
> +static FORCEINLINE ULONG
> +__DriverGetQueueMax(
> +    VOID
> +    )
> +{
> +    return Driver.QueueMax;
> +}
> +
> +ULONG
> +DriverGetQueueMax(
> +    VOID
> +    )
> +{
> +    return __DriverGetQueueMax();
> +}
> +
>  DRIVER_UNLOAD       DriverUnload;
> 
>  VOID
> @@ -254,6 +282,7 @@ DriverEntry(
>      HANDLE              ParametersKey;
>      HANDLE              AddressesKey;
>      ULONG               Index;
> +    ULONG               Queues;
>      NTSTATUS            status;
> 
>      ASSERT3P(__DriverGetDriverObject(), ==, NULL);
> @@ -304,6 +333,13 @@ DriverEntry(
> 
>      __DriverSetAddressesKey(AddressesKey);
> 
> +    status = RegistryQueryDwordValue(ParametersKey,
> +                                     "MultiQueueMaxQueues",
> +                                     &Queues);
> +    if (!NT_SUCCESS(status))
> +        Queues = MAXIMUM_PROCESSORS;
> +    __DriverSetQueueMax(Queues);
> +
>      RegistryCloseKey(ServiceKey);
> 
>      DriverObject->DriverExtension->AddDevice = AddDevice;
> diff --git a/src/xenvif/driver.h b/src/xenvif/driver.h
> index cdef7d1..9375930 100644
> --- a/src/xenvif/driver.h
> +++ b/src/xenvif/driver.h
> @@ -52,6 +52,11 @@ DriverGetAliasesKey(
>      VOID
>      );
> 
> +extern ULONG
> +DriverGetQueueMax(
> +    VOID
> +    );
> +

Again, need a clearer name.

  Paul

>  typedef struct _XENVIF_PDO  XENVIF_PDO, *PXENVIF_PDO;
>  typedef struct _XENVIF_FDO  XENVIF_FDO, *PXENVIF_FDO;
> 
> --
> 1.9.4.msysgit.1


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