That shouldn't matter. The mbuf size is allocated when you create the mempool, and data_len/pkt_len are just to specify the size of the total packet and each segment. The underlying storage size is still the same.
Have you checked to see if it's potentially a hugepage issue? On Sun, Jun 7, 2020, 02:59 Alex Kiselev <[email protected]> wrote: > On 2020-06-07 04:41, Cliff Burdick wrote: > > I can't tell from your code, but you assigned nb_rx to the number of > > packets received, but then used vec_size, which might be larger. Does > > this happen if you use nb_rx in your loops? > > No, this doesn't happen. > I just skip the part of the code that translates nb_rx to vec_size, > since that code is double checked. > > My actual question now is about possible impact of using > incorrect values of mbuf's pkt_len and data_len fields. > > > > > On Sat, Jun 6, 2020 at 5:59 AM Alex Kiselev <[email protected]> > > wrote: > > > >>> 1 июня 2020 г., в 19:17, Stephen Hemminger > >> <[email protected]> написал(а): > >>> > >>> On Mon, 01 Jun 2020 15:24:25 +0200 > >>> Alex Kiselev <[email protected]> wrote: > >>> > >>>> Hello, > >>>> > >>>> I've got a segmentation fault error in my data plane path. > >>>> I am pretty sure the code where the segfault happened is ok, > >>>> so my guess is that I somehow received a corrupted mbuf. > >>>> How could I troubleshoot this? Is there any way? > >>>> Is it possible that other threads of the application > >>>> corrupted that mbuf? > >>>> > >>>> I would really appriciate any advice. > >>>> Thanks. > >>>> > >>>> DPDK 18.11.3 > >>>> NIC: 82599ES > >>>> > >>>> Code: > >>>> > >>>> nb_rx = rte_eth_rx_burst(port_id, queue_id, pkts_burst, > >>>> MAX_PKT_BURST); > >>>> > >>>> ... > >>>> > >>>> for (i=0; i < vec_size; i++) { > >>>> rte_prefetch0(rte_pktmbuf_mtod(m_v[i], void *)); > >>>> > >>>> for (i=0; i < vec_size; i++) { > >>>> m = m_v[i]; > >>>> eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *); > >>>> eth_type = rte_be_to_cpu_16(eth_hdr->ether_type); > >> <--- > >>>> Segmentation fault > >>>> ... > >>>> > >>>> #0 rte_arch_bswap16 (_x=<error reading variable: Cannot access > >> memory > >>>> at address 0x4d80000000053010>) > >>> > >>> Build with as many of the debug options turned on in the DPDK > >> config, > >>> and build with EXTRA_CFLAGS of -g. > >> > >> Could using an incorrect (a very big one) value of mbuf pkt_len and > >> data_len while transmitting cause mbuf corruption and following > >> segmentation fault on rx? >
