[dpdk-dev] Unable to get multi-segment mbuf working for ixgbe

[dpdk-dev] Unable to get multi-segment mbuf working for ixgbe

[Clarylin L]

Hello,

I am trying to use multi-segment mbuf to receive large packet. I enabled
jumbo_frame and enable_scatter for the port and was expecting mbuf chaining
would be used to receive packets larger than the mbuf size (which was set
to 2048).

When sending 3000-byte (without fragmentation) packet from another non-dpdk
host, I didn't see packet was received by the ixgbe PMD driver.

After a quick debugging session I found that the following statement
in ixgbe_recv_scattered_pkts
(ixgbe_rxtx.c) is
always true and break the loop in case of large packet, while it's not the
case for small packet (smaller than mbuf size):

if (! staterr & rte_cpu_to_le32(IXGBE_RXDADV_STAT_DD))
    break;

Is enabling jumbo_frame and enable_scatter good enough to get started the
mbuf chaining?

Appreciate any input! Thanks.

Re: [dpdk-dev] Unable to get multi-segment mbuf working for ixgbe

[Clarylin L]

Any pointers to what the issue could be? thanks

On Fri, Mar 25, 2016 at 4:13 PM, Clarylin L <clearasu@gmail.com> wrote:

> Hello,
>
> I am trying to use multi-segment mbuf to receive large packet. I enabled
> jumbo_frame and enable_scatter for the port and was expecting mbuf chaining
> would be used to receive packets larger than the mbuf size (which was set
> to 2048).
>
> When sending 3000-byte (without fragmentation) packet from another
> non-dpdk host, I didn't see packet was received by the ixgbe PMD driver.
>
> After a quick debugging session I found that the following statement in ixgbe_recv_scattered_pkts
> (ixgbe_rxtx.c) is
> always true and break the loop in case of large packet, while it's not the
> case for small packet (smaller than mbuf size):
>
> if (! staterr & rte_cpu_to_le32(IXGBE_RXDADV_STAT_DD))
>     break;
>
> Is enabling jumbo_frame and enable_scatter good enough to get started the
> mbuf chaining?
>
> Appreciate any input! Thanks.
>

Re: [dpdk-dev] Unable to get multi-segment mbuf working for ixgbe

[Bruce Richardson]

On Mon, Mar 28, 2016 at 10:05:40AM -0700, Clarylin L wrote:
> Any pointers to what the issue could be? thanks
> 
> On Fri, Mar 25, 2016 at 4:13 PM, Clarylin L <clearasu@gmail.com> wrote:
> 
> > Hello,
> >
> > I am trying to use multi-segment mbuf to receive large packet. I enabled
> > jumbo_frame and enable_scatter for the port and was expecting mbuf chaining
> > would be used to receive packets larger than the mbuf size (which was set
> > to 2048).
> >
> > When sending 3000-byte (without fragmentation) packet from another
> > non-dpdk host, I didn't see packet was received by the ixgbe PMD driver.
> >
> > After a quick debugging session I found that the following statement in ixgbe_recv_scattered_pkts
> > (ixgbe_rxtx.c) is
> > always true and break the loop in case of large packet, while it's not the
> > case for small packet (smaller than mbuf size):
> >
> > if (! staterr & rte_cpu_to_le32(IXGBE_RXDADV_STAT_DD))
> >     break;
> >
> > Is enabling jumbo_frame and enable_scatter good enough to get started the
> > mbuf chaining?

What did you configure for the max MTU for jumbo frames? What do the port stats
and extended stats (xstats) report. Is there an error counter there that is
incrementing that could give a hint as to what the problem is.

/Bruce

> >
> > Appreciate any input! Thanks.
> >