netdev - Re: [PATCH 1/1] cbq: incorrect processing of high limits

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] [day] [month] [year] [list]

Date:	Tue, 02 Apr 2013 14:30:54 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	vvs@...allels.com, netdev@...r.kernel.org, kuznet@...allels.com,
	jhs@...atatu.com
Subject: Re: [PATCH 1/1] cbq: incorrect processing of high limits

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Mon, 01 Apr 2013 09:24:36 -0700

> On Mon, 2013-04-01 at 17:01 +0400, Vasily Averin wrote:
>> currently cbq works incorrectly for limits > 10% real link bandwidth,
>> and practically does not work for limits > 50% real link bandwidth.
>> Below are results of experiments taken on 1 Gbit link
>> 
>>  In shaper | Actual Result
>> -----------+---------------
>>   100M     | 108 Mbps
>>   200M     | 244 Mbps
>>   300M     | 412 Mbps
>>   500M     | 893 Mbps
>> 
>> This happen because of q->now changes incorrectly in cbq_dequeue():
>> when it is called before real end of packet transmitting,
>> L2T is greater than real time delay, q_now gets an extra boost
>> but never compensate it.
>> 
>> To fix this problem we prevent change of q->now until its synchronization
>> with real time.
>> 
>> Signed-off-by: Vasily Averin <vvs@...nvz.org>
>> Reviewed-by: Alexey Kuznetsov <kuznet@....inr.ac.ru>
 ...
> Acked-by: Eric Dumazet <edumazet@...gle.com>

Applied, thanks.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html