netdev - Re: [PATCH] sch_htb.c consume the classes's tokens bellow the HTB_CAN

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]

Message-ID: <412e6f7f0911040321o22c536fdid078f6d2225a90a0@mail.gmail.com>
Date:	Wed, 4 Nov 2009 19:21:48 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	Jamal Hadi Salim <hadi@...erus.ca>, devik@....cz,
	netdev@...r.kernel.org
Subject: Re: [PATCH] sch_htb.c consume the classes's tokens bellow the 
	HTB_CAN_SEND level

On Wed, Nov 4, 2009 at 6:42 PM, Jarek Poplawski <jarkao2@...il.com> wrote:
> On Wed, Nov 04, 2009 at 05:16:42PM +0800, Changli Gao wrote:
> ...
>> It is just correct. You focus on 1 second fairness, while I focus on 2
>> seconds fairness.
>
> The whole example was very simplified, so it all would certainly
> differ in time and real sends, especially with an interaction of
> more classes. But, generally, main HTB algorithm seems to be quite
> well tested against various fair and unfair cases, starting from
> the author's examples:
> http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm
> so, I guess, this type of a bug would really show somewhere long time
> ago.
>

This documentation is old, and after the last update 5.5.2002, there
were still bugs: http://luxik.cdi.cz/~devik/qos/htb/ .

>> The token bucket and ctoken bucket both use cl->mbuffer to control
>> rate granularities. If we don't account token bucket when the
>> corresponding class in HTB_MAY_BORROW mode, the cl->mbuffer will
>> become useless.
>
> cl->mbuffer is only to limit some extreme effects, so more of an
> exception, not a main tool of rate control. (It really should be
> useless most of the time if classes don't stop sending and aren't
> deprived of their full rate for really long time.)
>

I don't think so. Although a class's tokens may be negative, but its
ctokens may be positive. Charging its tokens is to prevent its cmode
from being changed to HTB_CAN_SEND from HTB_CANT_SEND directly.


-- 
Regards，
Changli Gao(xiaosuo@...il.com)
--
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