linux-kernel - Re: [ath5k-devel] Unusually low speeds with ath5k and iwl3945

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 25 Nov 2008 20:46:04 +0100
From:	Benoit PAPILLAULT <benoit.papillault@...e.fr>
To:	Felix Fietkau <nbd@...nwrt.org>
CC:	Maxim Levitsky <maximlevitsky@...il.com>,
	Derek Smithies <derek@...ranet.co.nz>,
	ath5k-devel@...ts.ath5k.org, linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org, ipw3945-devel@...ts.sourceforge.net,
	wally@...blackmoor.net, Johannes Berg <johannes@...solutions.net>
Subject: Re: [ath5k-devel] Unusually low speeds with ath5k and iwl3945

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Felix Fietkau a écrit :
> While reading the code for calculating the frame duration, i noticed
> something odd: It doesn't seem to be taking into account the short
> vs long preamble distinction for ERP rates. IMHO this might be causing
> issues like this. I've seen similar behaviour a long time ago when testing
> iwl3945 against a Broadcom AP with exactly the same throughput drop (500-
> 600 kbits/s).
> When I analyzed the problem with an extra monitor mode card, I found out
> that the throughput drop is caused by a huge number of retransmissions,

In the test I've done, there was no retransmission at all (no
duplicates). I don't save a capture file, so I cannot tell for sure.

What is the code computing frame duration you are referring to? How it
could affect the hardware behavior?

> and if I remember correctly (I didn't look for this specifically back then),
> the retransmissions went down the rate scaling table until they hit the
> first non-ERP rate and that one worked on the first try.
> 
> Johannes, does that sound like a probable cause? If so, it should be easy
> to fix.
> 
> - Felix
> 

Regards,
Benoit
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org

iD8DBQFJLFX8OR6EySwP7oIRAp2pAJ0batdz64sh9L82CIKzkmVcLyANygCeOq5q
D18DQ/Ko9ggdGn5lmshlMJs=
=3efH
-----END PGP SIGNATURE-----
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/