[dpdk-users] Packets not processed when huge pages are not used

[Sergio Gonzalez Monroy]

On 21/10/2015 22:08, shesha Sreenivasamurthy (shesha) wrote:
> Wanted to add ring addresses information:
>
> PMD: ixgbe_dev_rx_queue_setup(): sw_ring=0x7fffa0979440 sw_sc_ring=0x7fffa0975300 hw_ring=0x7fffa097d580 dma_addr=0x7fffa097d580
>
> --
> - Thanks
> char * (*shesha) (uint64_t cache, uint8_t F00D)
> { return 0x0000C0DE; }
>
> From: Cisco Employee <shesha at cisco.com<mailto:shesha at cisco.com>>
> Date: Wednesday, October 21, 2015 at 1:30 PM
> To: "users at dpdk.org<mailto:users at dpdk.org>" <users at dpdk.org<mailto:users at dpdk.org>>
> Subject: Packets not processed when huge pages are not used
>
> Hi,
>   I have a packet processing application running correctly using hugepages with 82599 interface. However, when no-huge is set, I do not see any packets being processed by DPDK. When arp packets are sent to this interface, I see them being received by the device (BPRC counter gets incremented). However, the DD register does not get set by the hardware. Therefore, _recv_raw_pkts_vec() returns thinking that there are no packets (shown below). Therefore, when huge pages are not used, I suspect that some DMA configuration is getting messed up. Any tips on how to go about finding the issue will be helpful.
>
> drivers/net/ixgbe/ixgbe_rxtx_vec.c
> 303     /* Before we start moving massive data around, check to see if
> 304      * there is actually a packet available */
> 305     if (!(rxdp->wb.upper.status_error &
> 306                 rte_cpu_to_le_32(IXGBE_RXDADV_STAT_DD)))
> 307         return 0;
>
> Observation: In lib/librte_eal/linuxapp/eal/eal_memory.c::rte_eal_hugepage_init() physical memory is set to be same as virtual (mcfg->memseg[0].phys_addr = (phys_addr_t)(uintptr_t)addr;). Is that expected ?
Hi Shesha,

It is a known issue:
http://dpdk.org/doc/guides/rel_notes/known_issues.html#pmd-does-not-work-with-no-huge-eal-command-line-parameter

It should work with IOMMU=on and VFIO driver, but I haven't verified 
that myself.

Sergio