We are experiencing a data loss issue on our QNX x86, with an application that reads and writes to a board at roughly 1kHz over UDP. We have recently observed that data in both directions get dropped quite frequently (about ten times per second), and it seems to happen whenever the read and write are scheduled to occur close to each other in time. Looking at the kernel trace of the QNX machine, we don't even see the interrupt for the missing incoming UDP packet. When capturing traffic over a mirroring network switch, we are able to see this missing packet on the wire, but are not able to see the outgoing packet that should be occuring around the same time.

We have not been able to find any other unusual behavior in either kernel traces or wireshark capture, and are particularly buffled about the bi-directional nature of this problem, given that the UDP write should not involve interrupts. Has anyone seen something like this before? Any suggestions or recommended tools are appreciated!



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OSTech
http://community.qnx.com/sf/go/post119200
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