Re: [dpdk-dev] [PATCH v2 3/3] vdpa/mlx5: control completion queue event mode

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 6/25/20 3:30 PM, Matan Azrad wrote:
> The CQ polling is necessary in order to manage guest notifications when
> the guest doesn't work with poll mode (callfd != -1).
> 
> The CQ polling scheduling method can affect the host CPU utilization and
> the traffic bandwidth.
> 
> Define 3 modes to control the CQ polling scheduling:
> 
> 1. A timer thread which automatically adjusts its delays to the coming
>    traffic rate.
> 2. A timer thread with fixed delay time.
> 3. Interrupts: Each CQE burst arms the CQ in order to get an interrupt
>    event in the next traffic burst.
> 
> When traffic becomes off, mode 3 is taken automatically.
> 
> The interrupt management takes a lot of CPU cycles but forward traffic
> event to the guest very fast.
> 
> Timer thread save the interrupt overhead but may add delay for the guest
> notification.
> 
> Add device arguments to control on the mode.
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>
> ---
>  doc/guides/vdpadevs/mlx5.rst        | 32 ++++++++++++++++++++
>  drivers/vdpa/mlx5/mlx5_vdpa.c       | 58 +++++++++++++++++++++++++++++++++++++
>  drivers/vdpa/mlx5/mlx5_vdpa.h       | 13 +++++++++
>  drivers/vdpa/mlx5/mlx5_vdpa_event.c | 56 +++++++++++++++++++++++++----------
>  4 files changed, 144 insertions(+), 15 deletions(-)

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime