Re: [PATCH] vhost: do deep copy while reallocate vq

["Yang, Zhiyong" <zhiyong.yang@intel.com>]

> -----Original Message-----
> From: Chen, Junjie J
> Sent: Monday, January 15, 2018 5:15 PM
> To: Yang, Zhiyong <zhiyong.yang@intel.com>; yliu@fridaylinux.org;
> maxime.coquelin@redhat.com
> Cc: dev@dpdk.org
> Subject: RE: [dpdk-dev] [PATCH] vhost: do deep copy while reallocate vq
> 
> Hi
> 
> > > @@ -227,6 +227,7 @@ vhost_user_set_vring_num(struct virtio_net *dev,
> > >  				"zero copy is force disabled\n");
> > >  			dev->dequeue_zero_copy = 0;
> > >  		}
> > > +		TAILQ_INIT(&vq->zmbuf_list);
> > >  	}
> > >
> > >  	vq->shadow_used_ring = rte_malloc(NULL, @@ -261,6 +262,9 @@
> > > numa_realloc(struct virtio_net *dev, int index)
> > >  	int oldnode, newnode;
> > >  	struct virtio_net *old_dev;
> > >  	struct vhost_virtqueue *old_vq, *vq;
> > > +	struct zcopy_mbuf *new_zmbuf;
> > > +	struct vring_used_elem *new_shadow_used_ring;
> > > +	struct batch_copy_elem *new_batch_copy_elems;
> > >  	int ret;
> > >
> > >  	old_dev = dev;
> > > @@ -285,6 +289,33 @@ numa_realloc(struct virtio_net *dev, int index)
> > >  			return dev;
> > >
> > >  		memcpy(vq, old_vq, sizeof(*vq));
> > > +		TAILQ_INIT(&vq->zmbuf_list);
> > > +
> > > +		new_zmbuf = rte_malloc_socket(NULL, vq->zmbuf_size *
> > > +			sizeof(struct zcopy_mbuf), 0, newnode);
> > > +		if (new_zmbuf) {
> > > +			rte_free(vq->zmbufs);
> > > +			vq->zmbufs = new_zmbuf;
> > > +		}
> >
> > You need to consider how to handle the case  ( rte_malloc_socket
> > return NULL).
> 
> If it failed to allocate new_zmbuf, it uses old zmbufs, so as to keep vhost
> alive.

It sounds reasonable, another question is, 
for the 3 blocks of memory being allocated,  If some succeed , others fails,  Does it mean that
the code will run on different socket?  What's the perf impact if it happens.

thanks
Zhiyong