Re: [dpdk-dev] [PATCH v5] vhost: add support for large buffers

[Flavio Leitner <fbl@sysclose.org>]

On Tue, 29 Oct 2019 10:02:57 +0100
David Marchand <david.marchand@redhat.com> wrote:

> On Tue, Oct 15, 2019 at 9:00 PM Flavio Leitner <fbl@sysclose.org>
> wrote:
> > diff --git a/lib/librte_vhost/virtio_net.c
> > b/lib/librte_vhost/virtio_net.c index 5b85b832d..da69ab1db 100644
> > --- a/lib/librte_vhost/virtio_net.c
> > +++ b/lib/librte_vhost/virtio_net.c
> > @@ -1289,6 +1289,93 @@ get_zmbuf(struct vhost_virtqueue *vq)
> >         return NULL;
> >  }
> >
> > +static void
> > +virtio_dev_extbuf_free(void *addr __rte_unused, void *opaque)
> > +{
> > +       rte_free(opaque);
> > +}
> > +
> > +static int
> > +virtio_dev_extbuf_alloc(struct rte_mbuf *pkt, uint32_t size)
> > +{
> > +       struct rte_mbuf_ext_shared_info *shinfo = NULL;
> > +       uint32_t total_len = RTE_PKTMBUF_HEADROOM + size;
> > +       uint16_t buf_len;
> > +       rte_iova_t iova;
> > +       void *buf;
> > +
> > +       /* Try to use pkt buffer to store shinfo to reduce the
> > amount of memory
> > +        * required, otherwise store shinfo in the new buffer.
> > +        */
> > +       if (rte_pktmbuf_tailroom(pkt) >= sizeof(*shinfo))
> > +               shinfo = rte_pktmbuf_mtod(pkt,
> > +                                         struct
> > rte_mbuf_ext_shared_info *);
> > +       else {
> > +               total_len += sizeof(*shinfo) + sizeof(uintptr_t);
> > +               total_len = RTE_ALIGN_CEIL(total_len,
> > sizeof(uintptr_t));
> > +       }
> > +
> > +       if (unlikely(total_len > UINT16_MAX))
> > +               return -ENOSPC;
> > +
> > +       buf_len = total_len;
> > +       buf = rte_malloc(NULL, buf_len, RTE_CACHE_LINE_SIZE);  
> 
> Using rte_malloc() means that the allocation can end up on any numa
> node. This external buffer might end up on a different node than the
> mbuf (which resides on mp->socket_id node).

Only if there is no memory in the local socket. It seems better than a
failure to me.

fbl