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From: Patrick McHardy <kaber@trash.net>
To: Stephen Hemminger <shemminger@osdl.org>
Cc: "David S. Miller" <davem@davemloft.net>, netdev@oss.sgi.com
Subject: Re: [PATCH] netem: account for packets in delayed queue in qlen
Date: Wed, 20 Apr 2005 16:00:56 +0200	[thread overview]
Message-ID: <42666098.5060409@trash.net> (raw)
In-Reply-To: <20050419110639.47767113@localhost.localdomain>

Stephen Hemminger wrote:
> There may be no sane way to do duplication without that.

This way doesn't work properly either. The classful qdiscs don't care
about their own q.qlen and just try to dequeue, if successful they
decrement q.qlen. When duplicating packets in an inner qdisc the
top-level qdisc's q.qlen will turn negative at some point (it's
unsigned, but returned as int from qdisc_restart) and will cause
qdisc_run() to spin forever.

> Other ways like injecting
> packets again at top of queue with a thread/tasklet seem rather gross

Injecting at the top is also problematic because it needs to
follow the same classification-path as the first packet, which
can only be guarenteed with stateless classification.

Regards
Patrick

  reply	other threads:[~2005-04-20 14:00 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-03-29 23:21 [PATCH] netem: account for packets in delayed queue in qlen Stephen Hemminger
2005-04-01  4:36 ` David S. Miller
2005-04-05 19:48 ` Patrick McHardy
2005-04-05 19:58   ` Stephen Hemminger
2005-04-07 19:04   ` Stephen Hemminger
2005-04-17 15:38     ` Patrick McHardy
2005-04-19  1:06       ` Stephen Hemminger
2005-04-20 14:00         ` Patrick McHardy [this message]
2005-04-21  3:20           ` Stephen Hemminger
2005-04-21 23:10             ` Patrick McHardy
2005-04-21 23:22               ` Stephen Hemminger
2005-04-21 23:39                 ` Patrick McHardy
2005-04-22  0:05                   ` jamal
2005-04-22  0:10                     ` Patrick McHardy
2005-04-22  0:32                       ` jamal
2005-04-22  0:40                         ` jamal

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