Messages in this thread | | | Date | Wed, 08 Aug 2012 16:03:41 -0700 (PDT) | Subject | Re: [PATCH RESEND] sched: add missing group change to qfq_change_class | From | David Miller <> |
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From: Paolo Valente <paolo.valente@unimore.it> Date: Tue, 7 Aug 2012 19:27:25 +0200
> [Resending again, as the text was corrupted by the email client] > > To speed up operations, QFQ internally divides classes into > groups. Which group a class belongs to depends on the ratio between > the maximum packet length and the weight of the class. Unfortunately > the function qfq_change_class lacks the steps for changing the group > of a class when the ratio max_pkt_len/weight of the class changes. > > For example, when the last of the following three commands is > executed, the group of class 1:1 is not correctly changed: > > tc disc add dev XXX root handle 1: qfq > tc class add dev XXX parent 1: qfq classid 1:1 weight 1 > tc class change dev XXX parent 1: classid 1:1 qfq weight 4 > > Not changing the group of a class does not affect the long-term > bandwidth guaranteed to the class, as the latter is independent of the > maximum packet length, and correctly changes (only) if the weight of > the class changes. In contrast, if the group of the class is not > updated, the class is still guaranteed the short-term bandwidth and > packet delay related to its old group, instead of the guarantees that > it should receive according to its new weight and/or maximum packet > length. This may also break service guarantees for other classes. > This patch adds the missing operations. > > Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Applied, thanks.
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