[dpdk-dev] dpdkvhostuser fail to alloc memory when receive packet from other host

["Du, Fan" <fan.du@intel.com>]

Hi,

I'm playing dpdkvhostuser ports with latest DPDK and ovs master tree with iperf benchmarking.
When kvm guest1(backed up dpdkvhostuser port)siting on HOST1 is receiving packets from either other physical HOST2,
or similar kvm guest2 with dpdkvhostuser port siting on HOST2. The connectivity will break, iperf show no bandwidth and stall finally.

Other test scenario like, two kvm guest sitting on one host, or a single kvm guest send packets to a physical host works like a charm.

Swiitch debug option on, dpdk lib spit as below:
VHOST_CONFIG: read message VHOST_USER_SET_VRING_CALL
VHOST_CONFIG: vring call idx:0 file:62
VHOST_CONFIG: read message VHOST_USER_SET_VRING_CALL
VHOST_CONFIG: vring call idx:0 file:58

VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0
VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0
VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0
VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0
VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0
VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0
VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0
VHOST_DATA: F0 Failed to allocate memory for mbuf. mbuf_pool:0x7fc7411ab5c0

After some tweaks of logging code, and looks like bad things happens within below code snippet:
In lib/librte_vhost/vhost_rxtx.c function: rte_vhost_dequeue_burst

612                 vb_offset = 0;
613                 vb_avail = desc->len;
614                 /* Allocate an mbuf and populate the structure. */
615                 m = rte_pktmbuf_alloc(mbuf_pool);
616                 if (unlikely(m == NULL)) {
617                         RTE_LOG(ERR, VHOST_DATA,
618                                 "F0 Failed to allocate memory for mbuf. mbuf_pool:%p\n", mbuf_pool);
619                         break;
620                 }
621                 seg_offset = 0;
622                 seg_avail = m->buf_len - RTE_PKTMBUF_HEADROOM;
623                 cpy_len = RTE_MIN(vb_avail, seg_avail);