Re: [dpdk-dev] [PATCH v4 2/2] virtio: one way barrier for split vring avail idx

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

On 4/24/20 5:39 AM, Joyce Kong wrote:
> In case VIRTIO_F_ORDER_PLATFORM(36) is not negotiated, then the frontend
> and backend are assumed to be implemented in software, that is they can
> run on identical CPUs in an SMP configuration.
> Thus a weak form of memory barriers like rte_smp_r/wmb, other than
> rte_cio_r/wmb, is sufficient for this case(vq->hw->weak_barriers == 1)
> and yields better performance.
> For the above case, this patch helps yielding even better performance
> by replacing the two-way barriers with C11 one-way barriers for avail
> index in split ring.
> 
> Signed-off-by: Joyce Kong <joyce.kong@arm.com>
> Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> ---
>  drivers/net/virtio/virtqueue.h | 20 ++++++++++++++++++--
>  lib/librte_vhost/virtio_net.c  | 14 +++++---------
>  2 files changed, 23 insertions(+), 11 deletions(-)

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

Thanks,
Maxime