[ovs-discuss] QoS Queue Priority Range

Ben Pfaff blp at ovn.org
Mon Jan 9 20:59:58 UTC 2017


On Mon, Jan 09, 2017 at 07:56:11PM +0100, Santhosh R P wrote:
> In the ovs-vswitchd.conf.db.5 manual, the range for "other_config :
> priority" in Queue table is mentioned as 0 to 4,294,967,295 (same as the
> number of queues that can be created).
> It is also mentioned that "Specific priority values are unimportant;
> only relative
> ordering matters."
> 
> The HTB qdisc, on the other hand, has queue priority ranging from 0 to 7. I
> am not very sure if HFSC can be configured with priority values for queues.
> 
> So, essentially if I create 6 queues from OVS with priority 1000, 1001,
> 1002, 1003, 1004 and 1005, by relative ordering, in tc-htb, the priority
> values must be 0 to 5 or 1 to 6.
> If this is not possible, I can use the HTB range directly, instead of
> choosing from a larger priority range.
> 
> What happens instead is, any priority value greater than 7 in OVS is
> assigned as 7 when I check that using tc, regardless of the number of
> queues created.
> 
> Is there an algorithm that provides the relative ordering for the priority?
> Is there a reason behind this design principle, instead of letting the user
> choose the range as in HTB?

OVS just passes this data through.  The range 0 to 4,294,967,295 is the
maximum range that the kernel interface supports.  For a qdisc that
doesn't support the full range, or that doesn't support priorities at
all, use only what it supports.


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