[Winpcap-users] Performance

[Loris Degioanni]

Try if using send queues, as explained at 
http://www.winpcap.org/docs/docs_40_1/html/group__wpcap__tut8.html, 
improves the performance. pcap_sendpacket() does a system call per 
packet, which is very slow.

Loris



Betsy Riggins wrote:
> 
> We are writing a tool that will basically pull IP packets from the 
> network, do some modifications and put the modified packet back on the 
> network.  We are writing this for multiple OSes and we see that 
> performance on Windows is really poor compared to the other OSes. I 
> wanted to check our design to find the most efficient method and also 
> solicit for any ideas about what would improve performance. We see very 
> low CPU usage, memory is also not constrained but packet throughput is 
> low. We have executed on single and multi-cpus with little difference in 
> throughput.
> 
> We have two different version, both showing the same performance.
> Design #1,
>         Find adapter and open each using pcap_open (InterfaceName, 1600,
>                                PCAP_OPENFLAG_PROMISCUOUS | 
> PCAP_OPENFLAG_NOCAPTURE_LOCAL | PCAP_OPENFLAG_MAX_RESPONSIVENESS,
>                                3600, NULL, errbuf);
>         pcap_setmintocopy to 0
>                Spin off thread(s) to loop reading / modifying /sending 
> packets (we have changed the number of threads and performance seems to 
> decrease as threads increase)
>                 pcap_next_ex        
>                 Modify
>                 pcap_sendpacket
> 
> Design #2        
>         Open adapter pcap_open_live capture timeout 0
>         pcap_setmintocopy to 0
>         Start threads (have tried 1 to 10, performance decreases with 
> threads increasing) :
>                 calls pcap_loop
>                 callback modifies packet
>                           pcap_sendpacket
>        
> We have tried increasing thread priority but it did not make a 
> significant performance improvement. The modify packet code is common to 
> linux and windows so we don't think that the problem lies in that 
> portion of the code. We are running tests on 1Gb/s  ethernet and we are 
> using the same hardware for both tests. Linux is showing around 100Mb/s 
> windows is around 10Mb/s.
> 
> 
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