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, 27 Nov 2007 12:58:49 +0100
From:	Jarek Poplawski <jarkao2@...pl>
To:	Joerg Pommnitz <pommnitz@...oo.com>
Cc:	netdev@...r.kernel.org
Subject: Re: Does tc-prio really work as advertised?

On Tue, Nov 27, 2007 at 02:54:10AM -0800, Joerg Pommnitz wrote:
> Jarek,
> this is all about outgoing packets, e.g. egress to use your word.
> It doesn't matter whether the packets are originated locally or
> whether the packets are forwarded from another host (I tried
> both).
> 
> To restate the problem: according to my observations the prio qdisc
> (and probably pfifo_fast, but I couldn't observe this) does not prioritize
> at all and always uses the band indicated by the first entry in the
> priomap.
> 
> By default the priomap looks like this:
> qdisc prio 1: dev eth1 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
> 
> there are 3 bands (1:1, 1:2 and 1:3). In theory the traffic should go through
> the different bands according to the TOS value of the packets. My observation
> is, that the traffic always uses the band pointed to by the first entry in the
> priomap. This value is 1 by default, so all traffic goes through band 1:2.
> 
> Now it's entirely possible that I did something stupid, but nobody came forward
> to show me the error of my ways (neither here nor on the lartc list).
> 

I don't think there could be anything stupid if something is maybe not
enough documented. But, this really should work - just like you've
found: TOS should be recalculated to skb->priority, and this should
affect prio. You should only consider that this recalculation isn't
done for all packets, but only forwarded ones (if I can remember, didn't
miss something, and nothing changed later...). So, are you still sure
you've tested such a case? (Btw., there are some other tools which can
change this priority field, so I hope you don't use them too.)

Jarek P.
-
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

Powered by blists - more mailing lists