Re: tcpdump vs libpcap : CPU usage shooting high for two simultaneous captures on wireless monitor interfaces

[abhinav narain <abhinavnarain10 () gmail com>]

Hi Guy,
Thanks for clearing this

> It does absolutely nothing whatsoever to discover whether there are other
> versions of tcpdump are running.


Ok

> Am I right to say that the two processes spin on some shared resource ?
>
> Given that I don't know what routines in the programs or libraries they
> use are running when they're consuming that CPU time, I have absolutely no
> idea whether you're right or not to say that.  That's why I wanted the
> profiling data - so that we *know* what routines are consuming the CPU
> time, not just *guessing*.
>
> I understand your point, but unfortunately I am unable to provide you the
information.

Can you show us the source code to the parts of your program that make
> libpcap calls?

thanks for taking the pains to have a look at the code.
The line has the pcap handle return.
https://github.com/abnarain/wifi_dump-tmpfs/blob/master/mac-darktest.c#L782

I have modified the mac80211 to send me radiotap info with extra
information, and hence i check to
see the radiotap header length to differentiate between the packet and copy
the various parts of
buffer into a separate table, write it to a file and ship it from the
router.

The other fancy thing which I am doing is setting a SIGPROCMASK to capture
alarms
to get to a handler which writes into the file every x minute(and if the
table is full)

This file only deals with the pcap code.
-
Abhinav
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