Is netmap jumbo frames broken in STABLE?

[Luigi Rizzo]

On Mon, Jun 6, 2016 at 3:22 PM, Andrew Vylegzhanin <avv314 at gmail.com> wrote:

> Hello all,
>
>
> I have an application that uses netmap for capture jumbo frames. The frames
> are fixed size and have fixed rate (for example size 5166, rate 50000 pps).
> The frames are pure Ethernet, without IP header.
>
>
> Everything works fine in 10.0-RELEASE, 10.1-RELEASE.
>
>
> Starting from 10.3 and actual 10-STABLE I've got wrong data from netmap
> ring. It's looks like packet data broke and packet split on two parts 4092
> and 1070 bytes,  where original size was 5166.
>
> A code ring precessing is based on macros from netmap_user.h :
>
>
>         n = nm_ring_space(ring);
>
>         for (rx = 0; rx < limit; rx++) {
>
>                 struct netmap_slot *slot = &ring->slot[cur];
>
>                 char *p = NETMAP_BUF(ring, slot->buf_idx);
>
>                 process_payload(p, slot->len, datapx);
>
>                 cur = nm_ring_next(ring, cur);
>
>         }
>
>         ring->head = ring->cur = cur;
>
>
> Here is netmap sysctl's:
>
> dev.netmap.buf_num=81920
>
> dev.netmap.ring_size=73728
>
> dev.netmap.buf_size=5248
>
>
> Hardware is Dell R720 (2x E5-2643 v2) with four Intel Ethernet 10G 2P X520
> Adapter. I use only one hardware queue per interface.
>
>
> BTW, may be a new version of Intel ixgbe driver (3.1.13-k) is a reason?
>
>
​Hi,
yes I suspect the problem may be in the new ixgbe driver,
probably it programs the hardware to limit buffer sizes to 4k
even when large MTUs are in use,
so the receiver will split
the incoming frame in two buffers, while netmap is expecting
only one.
I suggest to have a look at the ioctl handler (in the driver)
that handles the MTU setting and compare with the code
in the previous driver.

cheers
luigi


> Does it make sense to try with 11-CURRENT?
>
>
> Thank you in advance.
>
>
> --
>
> Andrew
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-- 
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 Prof. Luigi RIZZO, rizzo at iet.unipi.it  . Dip. di Ing. dell'Informazione
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