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  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, 21 Oct 2008 16:36:05 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	jarkao2@...il.com
Cc:	kaber@...sh.net, netdev@...r.kernel.org,
	herbert@...dor.apana.org.au, shemminger@...tta.com
Subject: Re: [PATCH] pkt_sched: sch_netem: Limit packet re-ordering
 functionality to tfifo qdisc.

From: Jarek Poplawski <jarkao2@...il.com>
Date: Fri, 17 Oct 2008 22:12:10 +0200

> pkt_sched: sch_netem: Limit packet re-ordering functionality to tfifo qdisc.
> 
> After introducing qdisc->ops->peek() method the only remaining user of
> qdisc->ops->requeue() is netem_enqueue() using this for packet
> re-ordering. According to Patrick McHardy: "a lot of the functionality
> of netem requires the inner tfifo anyways and rate-limiting is usually
> done on top of netem. So I would suggest so either hard-wire the tfifo
> qdisc or at least make the assumption that inner qdiscs are work-
> conserving." This patch tries the former.
> 
> Signed-off-by: Jarek Poplawski <jarkao2@...il.com>

This is an interesting patch.

But the thing that strikes me is this: Why don't we just let sch_netem do
the reordering inside of itself entirely and just get rid of all of this
->requeue() business?

sch_netem is just a black box, like any other packet scheduler node in
the tree, and so it can internally do the reordering with a self managed
packet list or similar.  All of this can be hidden inside of it's ->dequeue()
with some pkt_sch watchdog timer that fires to prevent stale packets sitting
in the reorder queue forever.

Anyways, just and idea and RFC, just like this patch ;-)
--
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