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Lost packets

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Lost packets

Postby gopyan » Tue Nov 27, 2012 10:14 am

Hello Friends.

I had very strange issue recently. I have two embedded computers (vp7 and vp9). Vp9 machine have intel i82544 network adapter , on the vp7 machine - pcnet32.
Qnx version 6.4.0.

On the vp9 machine I don't lost udp packets, but on vp7 I regulary lost packets.

If I invoke "pidin -p io-pkt-v4-hc mem" I see , that pcnet32 network driver (devn-pcnet.so) is work via devnp-shim.so. But on vp9 machine network adapter (devnp-i82544.so) work without devnp-shim.so. May be this is a core of the problem??? And how I can play with network adapter options??????????
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Re: Lost packets

Postby mario » Tue Nov 27, 2012 6:32 pm

How do you detect packets are lost, via nicinfo, via netstat -s or through your application. Packets can be lost at various stages of their travel
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Re: Lost packets

Postby gopyan » Tue Nov 27, 2012 11:29 pm

I invoke tcpdump on vp7 machine and invoke tcpdump on the send side. On send side I see certain packet , but on the receive side (vp7 machine) I don't .
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Re: Lost packets

Postby gopyan » Tue Nov 27, 2012 11:34 pm

netstat -s say that there is no problem)))))))))) , nicinfo also
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Re: Lost packets

Postby mario » Wed Nov 28, 2012 1:10 am

n theory if nicinfo doesn't report lost packet and netstat's -s " UDP dropped due to full socket buffers" is at 0, then it could be :

- A bug a 6.4.0
- A hardware problem
- tcpdump is throwing out packet
- The send side isn't really sending them
- Something else I haven't though of ;-)
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Re: Lost packets

Postby maschoen » Wed Nov 28, 2012 3:21 am

How about cabling? Try switching the cables and see if the problem moves or stays where it is.
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Re: Lost packets

Postby mario » Wed Nov 28, 2012 2:53 pm

mario wrote:n theory if nicinfo doesn't report lost packet and netstat's -s " UDP dropped due to full socket buffers" is at 0, then it could be :

- A bug a 6.4.0
- A hardware problem
- tcpdump is throwing out packet
- The send side isn't really sending them
- Something else I haven't though of ;-)


The apps may also be sending data to fast and not making it to the wire.
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Re: Lost packets

Postby gopyan » Thu Nov 29, 2012 5:34 am

I will try to switch cable and say about results.
mario wrote:The apps may also be sending data to fast and not making it to the wire.

Our traffic is light. How I can to increase needed buffers in network card????? And what is the needed buffers in network stack???? Tx and Rx descriptors??? Or buffers in the io-pkt???
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Re: Lost packets

Postby gopyan » Thu Nov 29, 2012 5:36 am

I forget to say THANK YOU for attention to my problem))))
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Re: Lost packets

Postby gopyan » Thu Nov 29, 2012 5:41 am

Forget to say that after autonegatiation stage pcnet32 adapter (in the vp7 machine) work in half-duplex mode. Maybe this key???
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Re: Lost packets

Postby maschoen » Thu Nov 29, 2012 8:31 am

gopyan wrote:Forget to say that after autonegatiation stage pcnet32 adapter (in the vp7 machine) work in half-duplex mode. Maybe this key???


I don't think you can increase a network card's buffers. There might be parameters for io-pkt, but I don't think that's your problem. The half-duplex suggests either a cable or a hub problem. If your cards are 100TX but the cables are not CAT5 (at least) that might cause the problem.
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Re: Lost packets

Postby gopyan » Thu Dec 20, 2012 2:46 pm

I notice one thing when my application invoked. If I run command "sloginfo -w -c" then I have three times in second
message -> "pcnet memory error".

Maybe someone have pcnet32 network adapter sources. What is the case when "pcnet memory error" message
generated??????

I invoke "top" command and see that 28M of memory are available, i.e. there is no memory problem.
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Re: Lost packets

Postby gopyan » Fri Dec 21, 2012 4:14 pm

Maschoen. Where are you??????????? ))))))))))))
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Re: Lost packets

Postby maschoen » Fri Dec 21, 2012 6:20 pm

gopyan wrote:I notice one thing when my application invoked. If I run command "sloginfo -w -c" then I have three times in second
message -> "pcnet memory error".

Maybe someone have pcnet32 network adapter sources. What is the case when "pcnet memory error" message
generated??????

I invoke "top" command and see that 28M of memory are available, i.e. there is no memory problem.


I don't know what that error means. It sounds like a hardware problem, either something bad on the card, or an incompatibility.
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Re: Lost packets

Postby gopyan » Sat Dec 22, 2012 3:06 am

How I can get pcnet sources??????????????
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