[dpdk-stable] [PATCH v6 4/7] vhost: fix NUMA reallocation with multiqueue

[Xia, Chenbo]

Hi Maxime,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin at redhat.com>
> Sent: Friday, June 18, 2021 10:04 PM
> To: dev at dpdk.org; david.marchand at redhat.com; Xia, Chenbo <chenbo.xia at intel.com>
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>; stable at dpdk.org
> Subject: [PATCH v6 4/7] vhost: fix NUMA reallocation with multiqueue
> 
> Since the Vhost-user device initialization has been reworked,
> enabling the application to start using the device as soon as
> the first queue pair is ready, NUMA reallocation no more
> happened on queue pairs other than the first one since
> numa_realloc() was returning early if the device was running.
> 
> This patch fixes this issue by only preventing the device
> metadata to be allocated if the device is running. For the
> virtqueues, a vring state change notification is sent to
> notify the application of its disablement. Since the callback
> is supposed to be blocking, it is safe to reallocate it
> afterwards.
> 
> Fixes: d0fcc38f5fa4 ("vhost: improve device readiness notifications")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin at redhat.com>
> ---
>  lib/vhost/vhost_user.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> index 82adf80fe5..51b96a0716 100644
> --- a/lib/vhost/vhost_user.c
> +++ b/lib/vhost/vhost_user.c
> @@ -488,12 +488,16 @@ numa_realloc(struct virtio_net *dev, int index)
>  	struct batch_copy_elem *new_batch_copy_elems;
>  	int ret;
> 
> -	if (dev->flags & VIRTIO_DEV_RUNNING)
> -		return dev;
> -
>  	old_dev = dev;
>  	vq = old_vq = dev->virtqueue[index];
> 
> +	/*
> +	 * If VQ is ready, it is too late to reallocate, it certainly already
> +	 * happened anyway on VHOST_USER_SET_VRING_ADRR.
> +	 */
> +	if (vq->ready)
> +		return dev;
> +
>  	ret = get_mempolicy(&newnode, NULL, 0, old_vq->desc,
>  			    MPOL_F_NODE | MPOL_F_ADDR);
> 
> @@ -558,6 +562,9 @@ numa_realloc(struct virtio_net *dev, int index)
>  		rte_free(old_vq);
>  	}
> 
> +	if (dev->flags & VIRTIO_DEV_RUNNING)
> +		goto out;
> +

Since we don't realloc when vq is ready, there is no case that vq not ready but
device still running, right?

Thanks,
Chenbo

>  	/* check if we need to reallocate dev */
>  	ret = get_mempolicy(&oldnode, NULL, 0, old_dev,
>  			    MPOL_F_NODE | MPOL_F_ADDR);
> --
> 2.31.1