Hi,

 

I'm currently working on a stream analyzing tool using winpcap. Unfortunately 
I'm facing the fact of packetloss on my PC...

 

The Setup: 4 streams á 40Mbit/s over a 1GBit/s switch connected to my PC via 
3Com 3C996B Gigabit or Intel 82567LM-3 Gigabit NIC (newest drivers of course). 
The system is powered by a Q9400 with plenty of ram. The CPU usage is below 
20%, half of it is used by the kernel. The transport-protocol used is not known 
by windows, so the frames should not be processed any further.

 

While the hardware should be capable of receiving 160Mbit/s, I'm not able to 
receive all frames correctly by using Wireshark or my tool. As all frames are 
numbered, I can see nondeterministic drops of 0-10 frames per second on all 
streams (The frames are fixed size of 1060 byte).

 

As far as my application goes I tried optimizing kernel- & user-space buffers 
(both up to 50mb) and only reading the first 32 byte of every frame 
(pcap_open_live parameter). Also there was no difference between pcap_next_ex, 
pcap_loop and pcap_dispatch. pcap_stats_ex also tells me no frames have been 
dropped. The DPC latency without load is about 10µs, using Wireshark or my 
analyzer (default buffer) will raise the latency up to 30µs. Increasing the 
buffer size will raise the latency by factor 25. Also applying a filter and 
only capture one of the streams will result in packetloss...

 

Ideas, anyone?

 

Kind regards,

Dominik


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