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Forum Topic - missing interrupts: (3 Items)
   
missing interrupts  
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!
Re: missing interrupts  
can you share some details on HW and SW (ie which version of QNX you're using, which drivers .... )?

On Wed, 2018-10-10 at 17:24 -0400, Chen Chen wrote:

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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Re: missing interrupts  
Oh yes... we are using QNX 6.6 with APIC bsp, Kontron ktqm87 motherboard, and Intel i350-t4 network card