Hi, Peng,
Patch[1] is an example in OVS-DPDK to support muti-segments mbufs.
It was not applied to OVS upstream finally. Maybe muti-segments mbuf
feature is not accepted by the community although we need this feature
when we want to use some virtual PMD drivers such as vhost-user,
virtio-user to support TSO or GRO.
[1]:
https://patchwork.ozlabs.org/project/openvswitch/cover/[email protected]/
On Mon, Mar 21, 2022 at 1:54 PM Peng He <[email protected]> wrote:
>
> Hi,
> do you have future plan to support mbuf chaining for dp-packet?
> as I see you've actually relax some check on dp-packet in this
> patch.
>
> thanks
>
> David Marchand <[email protected]> 于2022年3月18日周五 23:34写道：
>
> > DPDK based dp-packets points to data buffers that can't be expanded
> > dynamically.
> > Their layout is as follows:
> > - a 128 bytes headroom chosen at DPDK build time (RTE_PKTMBUF_HEADROOM),
> > - a maximum size chosen at mempool creation,
> >
> > In some usecases though (like encapsulating with multiple tunnels),
> > a 128 bytes headroom is too short.
> >
> > Dynamically allocate buffers in DPDK memory and make use of DPDK
> > external buffers API (previously used for userspace TSO).
> >
> > Signed-off-by: David Marchand <[email protected]>
> > ---
> > lib/dp-packet.c | 17 ++++++++++++++++-
> > lib/netdev-dpdk.c | 47 +++++++++++++++++++++++++++++++++++------------
> > lib/netdev-dpdk.h | 3 +++
> > 3 files changed, 54 insertions(+), 13 deletions(-)
> >
> > diff --git a/lib/dp-packet.c b/lib/dp-packet.c
> > index 35c72542a2..07fa67b1a1 100644
> > --- a/lib/dp-packet.c
> > +++ b/lib/dp-packet.c
> > @@ -250,8 +250,23 @@ dp_packet_resize(struct dp_packet *b, size_t
> > new_headroom, size_t new_tailroom)
> > new_allocated = new_headroom + dp_packet_size(b) + new_tailroom;
> >
> > switch (b->source) {
> > - case DPBUF_DPDK:
> > + case DPBUF_DPDK: {
> > +#ifdef DPDK_NETDEV
> > + uint32_t buf_len;
> > +
> > + buf_len = new_allocated;
> > + new_base = netdev_dpdk_extbuf_allocate(&buf_len);
> > + if (!new_base) {
> > + out_of_memory();
> > + }
> > + ovs_assert(buf_len <= UINT16_MAX);
> > + dp_packet_copy__(b, new_base, new_headroom, new_tailroom);
> > + netdev_dpdk_extbuf_replace(b, new_base, buf_len);
> > + break;
> > +#else
> > OVS_NOT_REACHED();
> > +#endif
> > + }
> >
> > case DPBUF_MALLOC:
> > if (new_headroom == dp_packet_headroom(b)) {
> > diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> > index fbc3b42d84..47e16f22c5 100644
> > --- a/lib/netdev-dpdk.c
> > +++ b/lib/netdev-dpdk.c
> > @@ -2646,41 +2646,64 @@ out:
> > }
> > }
> >
> > +void *
> > +netdev_dpdk_extbuf_allocate(uint32_t *data_len)
> > +{
> > + *data_len += sizeof(struct rte_mbuf_ext_shared_info) +
> > sizeof(uintptr_t);
> > + *data_len = RTE_ALIGN_CEIL(*data_len, sizeof(uintptr_t));
> > + return rte_malloc(NULL, *data_len, RTE_CACHE_LINE_SIZE);
> > +}
> > +
> > static void
> > netdev_dpdk_extbuf_free(void *addr OVS_UNUSED, void *opaque)
> > {
> > rte_free(opaque);
> > }
> >
> > +void
> > +netdev_dpdk_extbuf_replace(struct dp_packet *b, void *buf, uint32_t
> > data_len)
> > +{
> > + struct rte_mbuf *pkt = (struct rte_mbuf *) b;
> > + struct rte_mbuf_ext_shared_info *shinfo;
> > + uint16_t buf_len = data_len;
> > +
> > + shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
> > + netdev_dpdk_extbuf_free,
> > + buf);
> > + ovs_assert(shinfo != NULL);
> > +
> > + if (RTE_MBUF_HAS_EXTBUF(pkt)) {
> > + rte_pktmbuf_detach_extbuf(pkt);
> > + }
> > + rte_pktmbuf_attach_extbuf(pkt, buf, rte_malloc_virt2iova(buf),
> > buf_len,
> > + shinfo);
> > +}
> > +
> > static struct rte_mbuf *
> > dpdk_pktmbuf_attach_extbuf(struct rte_mbuf *pkt, uint32_t data_len)
> > {
> > uint32_t total_len = RTE_PKTMBUF_HEADROOM + data_len;
> > - struct rte_mbuf_ext_shared_info *shinfo = NULL;
> > + struct rte_mbuf_ext_shared_info *shinfo;
> > uint16_t buf_len;
> > void *buf;
> >
> > - total_len += sizeof *shinfo + sizeof(uintptr_t);
> > - total_len = RTE_ALIGN_CEIL(total_len, sizeof(uintptr_t));
> > -
> > + buf = netdev_dpdk_extbuf_allocate(&total_len);
> > + if (OVS_UNLIKELY(buf == NULL)) {
> > + VLOG_ERR("Failed to allocate memory using rte_malloc: %u",
> > total_len);
> > + return NULL;
> > + }
> > if (OVS_UNLIKELY(total_len > UINT16_MAX)) {
> > + netdev_dpdk_extbuf_free(NULL, buf);
> > VLOG_ERR("Can't copy packet: too big %u", total_len);
> > return NULL;
> > }
> >
> > buf_len = total_len;
> > - buf = rte_malloc(NULL, buf_len, RTE_CACHE_LINE_SIZE);
> > - if (OVS_UNLIKELY(buf == NULL)) {
> > - VLOG_ERR("Failed to allocate memory using rte_malloc: %u",
> > buf_len);
> > - return NULL;
> > - }
> > -
> > - /* Initialize shinfo. */
> > shinfo = rte_pktmbuf_ext_shinfo_init_helper(buf, &buf_len,
> > netdev_dpdk_extbuf_free,
> > buf);
> > if (OVS_UNLIKELY(shinfo == NULL)) {
> > - rte_free(buf);
> > + netdev_dpdk_extbuf_free(NULL, buf);
> > VLOG_ERR("Failed to initialize shared info for mbuf while "
> > "attempting to attach an external buffer.");
> > return NULL;
> > diff --git a/lib/netdev-dpdk.h b/lib/netdev-dpdk.h
> > index 699be3fb41..95594f07fb 100644
> > --- a/lib/netdev-dpdk.h
> > +++ b/lib/netdev-dpdk.h
> > @@ -31,6 +31,9 @@ struct netdev;
> > void netdev_dpdk_register(void);
> > void free_dpdk_buf(struct dp_packet *);
> >
> > +void *netdev_dpdk_extbuf_allocate(uint32_t *);
> > +void netdev_dpdk_extbuf_replace(struct dp_packet *, void *, uint32_t);
> > +
> > bool netdev_dpdk_flow_api_supported(struct netdev *);
> >
> > int
> > --
> > 2.23.0
> >
> > _______________________________________________
> > dev mailing list
> > [email protected]
> > https://mail.openvswitch.org/mailman/listinfo/ovs-dev
> >
>
>
> --
> hepeng
> _______________________________________________
> dev mailing list
> [email protected]
> https://mail.openvswitch.org/mailman/listinfo/ovs-dev
--
Thanks, Harold.
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