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Date:      Fri, 7 Dec 2001 11:39:20 +0100
From:      Marco Molteni <molter@tin.it>
To:        freebsd-net@FreeBSD.ORG
Cc:        Doug Ambrisko <ambrisko@ambrisko.com>
Subject:   Re: pcap_open_live() takes 1 sec to complete?
Message-ID:  <20011207113920.B21525@cobweb.example.org>
In-Reply-To: <200112061823.fB6INsP49553@ambrisko.com>; from ambrisko@ambrisko.com on Thu, Dec 06, 2001 at 10:23:52AM -0800
References:  <20011206141330.A17077@cobweb.example.org> <200112061823.fB6INsP49553@ambrisko.com>

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On 2001-12-06, Doug Ambrisko wrote:
> Marco Molteni writes:
> | I am writing a small program that does a pcap_open_live() on the
> | Aironet an device, PCMCIA mode. System is a recent -stable on a
> | Toshiba Portege 7200 laptop.
> |
> | Now, pcap_open_live() takes more than 1 sec to return. Is this long
> | time expected?
> 
> Hmm, don't seem to recall that.  My system is busy doing a make world
> and stuff.  I just tried it and on my busy machine it was less then
> a second.  Note I was not in RFMON mode.  It might take longer when
> I have to switch into RFMON mode.  I can try that later.  You might
> try to compare it without RFMON if you are using RFMON.

Actually I am in RFMON mode.

Also, I found something strange: the first time that pcap_open_live()
is called, it is fast (50 ms), but subsequent calls are slow (1000 ms).
If I remove and reinsert the card, first call is once more fast.

# ./airomon an0
set monitor mode: 23 ms
pcap_open_live: 52 ms
^C

# ./airomon an0
set monitor mode: 24 ms
pcap_open_live: 1089 ms
^C

> FYI, I put a sample BPF packet dumper up at:
>         http://www.ambrisko.com/doug/an/dump_packet/
> I used it to debug the 802.11 packet problem and to look at the raw
> Aironet Header packets.
> 
> You'll see it has some test code to check gap length.
> 
> This is on -stable with my 802.11 aligment fix.

thanks a lot for this, I will try it out.

marco

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