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

[Harold Demure]

Hello Shyam,
   Thank you for your suggestion. I will try what you say. However, this
problem arises only with specific workloads. For example, if the clients
only send requests of 1 frame, everything runs smoothly even with 16 active
queues. My problem arises only with bigger payloads and multiple queues.
Shouldn't this suggest that the problem is not "simply" that my NIC drops
packets with > X active queues?

Regards,
  Harold

2017-07-18 7:50 GMT+02:00 Shyam Shrivastav <shrivastav.shyam at gmail.com>:

> As I understand the problem disappears with 1 RX queue on server. You can
> reduce number of queues on server from 8 and arrive at an optimal value
> without packet loss.
> For intel 82599 NIC packet loss is experienced with more than 4 RX queues,
> this was reported in dpdk dev or user mailing list, read in archives
> sometime back while looking for similar information with 82599.
>
> On Tue, Jul 18, 2017 at 4:54 AM, Harold Demure <harold.demure87 at gmail.com>
> wrote:
>
>> 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 :(
>> Regards,
>>   Harold
>>
>>
>>
>> >
>> > 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)?*
>> >
>>
>
>