Jan Kiszka wrote:
> Robert Gubler wrote:
>> Hello,
>>
>> I am calling send() at 500 usec intervals with 1514 byte packets (the MTU
>> size). Occasionally send() will fail with errno set to: "No buffer space
>> available."
>>
>> If I did my math right the theoretical maximum number of packets at 500 usec
>> intervals is approximately 4. So, at 1 packet every 500 usec I am sending
>> at a rate approximately equal to 25 MBit/s.
>
> Hmm, maybe the NIC is a bit too slow with handing back the freed buffers
> (unlikely, though). This problem would be a good candidate for runtime
> analysis via LTTng - but the patches required for this are currently
> still only suited for brave early adopters.
>
>> So I guess my first question is, can this buffer space, that the error
>> refers to be increased? Have I really reached the maximum number of packets
>> I can transmit?
>
> Please have a look at Documentation/README.pools.
>
> However, I would suggest trying to find out the reason for this buffer
> shortage instead of only increasing the pools (not saying the latter is
> wrong per se). An alternative approach might be the I-pipe kernel
^^^^^
to LTTng> function tracer with a long backtrace range so that you can watch out > for packet submission vs. buffer releases before that error was > reported. This will also require to understand a bit of RTnet internals > and its data flow, let us know if you want to go this path and need more > help. > >> I am using a recently copy of RTnet (SVN revision 1139, I think). Also, I >> am using the rt_eepro100 module. >> >> -Rob >> > > Jan >
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