Wireshark-dev: Re: [Wireshark-dev] Why does the extcap stuff take so long to start up?
Hello Guy,
Could you check if any of extcap binaries generates that delay? (check
one by one) On "my" Ubuntu 12.04:
my_extcap[4] = {androiddump, randpktdump, udpdump, my custom extcap};
$ time ./run/tshark -D # returns 21 interfaces
real 0m0.188s
user 0m0.115s
sys 0m0.061s
$ time ./run/tshark -D # with connected phone + androiddump (+7 interfaces)
real 0m0.464s
user 0m0.115s
sys 0m0.077s
~200ms for androiddump is very ice (expected), not a bug (if ~4s it is a bug).
$ time ./run/tshark -D # extcap dir renamed (removed) - 13 interfaces now
real 0m0.141s
user 0m0.106s
sys 0m0.030s
Summary: no problem on my platform.
PS. Similar results when opening small capture file.
It seems that initializing interfaces takes significant time, but my
question is: why does it <must> be done if user only try to open
capture file? Could we do not initialize nor extcap neither libpcap
interfaces in that case? ....or do it in background...
2017-03-27 1:05 GMT+02:00 Guy Harris <guy@xxxxxxxxxxxx>:
> $ time ./tshark -r /tmp/nothing.pcap # reading an empty pcap file
> # with all the extcap binaries present
> real 0m4.089s
> user 0m0.694s
> sys 0m2.637s
>
> $ time ./tshark -r /tmp/nothing.pcap # reading the same empty pcap file
> # with the extcap binaries removed
> real 0m0.540s
> user 0m0.310s
> sys 0m0.220s
>
> So it took *four seconds* of real time, and over *two seconds* of system-mode CPU time, to run, I guess, extcap_register_preferences(), and all the stuff it runs.
>
> Does it need to take that long?
>
> If it does need to take that long, do we need to do that if we're not capturing?
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--
Michał Łabędzki
