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

["Xia, Chenbo" <chenbo.xia@intel.com>]

Hi Maxime,

> -----Original Message-----
> From: stable <stable-bounces@dpdk.org> On Behalf Of Xia, Chenbo
> Sent: Friday, June 25, 2021 10:56 AM
> To: Maxime Coquelin <maxime.coquelin@redhat.com>; dev@dpdk.org;
> david.marchand@redhat.com
> Cc: stable@dpdk.org
> Subject: Re: [dpdk-stable] [PATCH v6 4/7] vhost: fix NUMA reallocation
> with multiqueue
> 
> Hi Maxime,
> 
> > -----Original Message-----
> > From: Maxime Coquelin <maxime.coquelin@redhat.com>
> > Sent: Friday, June 18, 2021 10:04 PM
> > To: dev@dpdk.org; david.marchand@redhat.com; Xia, Chenbo
> <chenbo.xia@intel.com>
> > Cc: Maxime Coquelin <maxime.coquelin@redhat.com>; stable@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@dpdk.org
> >
> > Signed-off-by: Maxime Coquelin <maxime.coquelin@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?

Sorry, I forgot DEV_RUNNING now only requires 1 qpair ready now ☹
Ignore above comments..

Thanks,
Chenbo

> 
> 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