I don't think so since they're completely independent mempools. I also didn't think the mtu function actually has anything to do with prepping the card for the mbuf size you want, and that it's typically done in rte_eth_dev_configure inside of eth_conf in rx_mode and tx_mode. I would have to look at the code to confirm, but also check what you're setting this structures to.
On Sun, Jun 7, 2020, 10:11 Alex Kiselev <[email protected]> wrote: > On 2020-06-07 17:21, Cliff Burdick wrote: > > The mbuf pool said be configured to be the size of the largest packet > > you expect to receive. If you're getting packets longer than that, I > > would expect you to see problems. Same goes for transmitting; I > > believe it will just read past the end of the mbuf data. > > I am using rte_eth_dev_set_mtu() call with mtu value that is consistent > with the mbuf size. Therefore I believe I don't have any overflow bugs > in the > RX code. > > And I've found a couple of bugs in the TX code. Both of them are > have to do with the incorrect use of pkt_len/data_len mbufs field. > > But, the crash happened while receiving packets, that's why > I am wondering could the bugs I found in the TX code cause the crush > in RX? > > > > > > On Sun, Jun 7, 2020, 06:36 Alex Kiselev <[email protected]> wrote: > > > >> On 2020-06-07 15:16, Cliff Burdick wrote: > >>> 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. > >> > >> It does matter. I've done some tests and after > >> sending a few mbufs with data_len/pkt_len bigger than the size > >> of mbuf's underlying buffer the app stops sending/receiving packets. > >> The PMD apparently goes beyong the mbuf's buffer, that's why > >> I sill think that my question about the impact of using incorrect > >> data_len/pkt is valid. > >> > >>> > >>> Have you checked to see if it's potentially a hugepage issue? > >> > >> Please, explain. > >> > >> The app had been working two monghts before the crush > >> and the load was 3-4 gbit/s, so no, I don't think that > >> something is wrong with hugepages on that machine. > >> > >>> > >>> 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? >
