Re: [PATCH BUGFIX] pkt_sched: sch_qfq: remove a source of high packet delay/jitter

[David Miller <davem@davemloft.net>]

From: Paolo Valente <paolo.valente@unimore.it>
Date: Tue, 16 Jul 2013 08:52:30 +0200

 ...
> This patch addresses this issue by just using the above
> 'instantaneous' value of the weight sum, instead of the maximum
> possible value, when updating the system virtual time.  After the
> instantaneous weight sum is decreased, QFQ+ may deviate from the ideal
> service for a time interval in the order of the time to serve one
> maximum-size packet for each backlogged class. The worst-case extent
> of the deviation exhibited by QFQ+ during this time interval [1] is
> basically the same as of the deviation described above (but, without
> this patch, QFQ+ suffers from such a deviation all the time). Finally,
> this patch modifies the comment to the function qfq_slot_insert, to
> make it coherent with the fact that the weight sum used by QFQ+ can
> now be lower than the maximum possible value.
> 
> [1] P. Valente, "Extending WF2Q+ to support a dynamic traffic mix",
> Proceedings of AAA-IDEA'05, June 2005.
> 
> Signed-off-by: Paolo Valente <paolo.valente@unimore.it>

Thank you for this amazing commit message.

Since you explained everything, even if I don't understand all of the
details of QFQ/QFQ+ I can in fact be confident in your change.

Applied and queued up for -stable, thanks!