[dpdk-users] Strange packet loss with multi-frame payloads

Harold Demure harold.demure87 at gmail.com
Tue Jul 18 01:24:46 CEST 2017

Hello again,
  I tried to convert my statically defined buffers into buffers allocated
through rte_malloc (as discussed in the previous email, see quoted text).
Unfortunately, the problem is still there :(

> 2. How do you know you have the packet loss?
> *I know it because some fragmented packets never get reassembled fully. If
> I print the packets seen by the server I see something like  "PCKT_ID 10
> FRAG 250, PCKT_ID 10 FRAG 252". And FRAG 251 is never printed.*
> *Actually, something strange that happens sometimes is that a core
> receives fragments of two packets and, say, receives   frag 1 of packet X,
> frag 2 of packet Y, frag 3 of packet X, frag 4 of packet Y.*
> *Or that, after "losing" a fragment for packet X, I only see printed
> fragments with EVEN frag_id for that packet X. At least for a while.*
> *This led me also to consider a bug in my implementation (I don't
> experience this problem if I run with a SINGLE client thread). However,
> with smaller payloads, even fragmented, everything runs smoothly.*
> *If you have any suggestions for tests to run to spot a possible bug in my
> implementation, It'd be more than welcome!*
> *MORE ON THIS: the buffers in which I store the packets taken from RX are
> statically defined arrays, like struct rte_mbuf*  temp_mbuf[SIZE].  SIZE
> can be pretty high (say, 10K entries), and there are 3 of those arrays per
> core. Can it be that, somehow, they mess up the memory layout (e.g., they
> intersect)?*

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