[ovs-dev] [ACL Meters 4/7] ovn: Add Meter and Meter_Band tables to the NB and SB databases.

Mark Michelson mmichels at redhat.com
Tue Jul 31 12:07:42 UTC 2018


On 07/30/2018 09:00 PM, Justin Pettit wrote:
> 
> 
>> On Jul 30, 2018, at 11:40 AM, Mark Michelson <mmichels at redhat.com> wrote:
>>
>> Hi Justin,
>>
>> I took a look through the patch series, and this is the only one that I had some immediate feedback on.
>>
>> First, it would be nice if we could refer to Meters by name when issuing DB commands. For instance `ovn-nbctl add Meter <meter_name> bands <band UUID>`.
> 
> Okay, I'll work on a follow-up patch to add that.  I didn't think it was a blocker for this series, though.
> 
>> Second, I noticed that the algorithm for computing southbound meter bands can result in a larger number of bands than is in the northbound table. For instance, you could issue the following:
>>
>> ovn-nbctl --id=@id create Meter_Band action=drop rate=1000 -- \
>> create Meter name=foo unit=kbps band=@id -- \
>> create Meter name=bar unit=kbps band=@id
>>
>> In the northbound database, you'll have one entry in the meter_band table. In the southbound database, you'll have two entries in the meter_band table. The algorithm does not take into account that multiple northbound meters may refer to the same meter_band. I'm not sure how big an issue this is (or really if it is an issue), but it surprised me a bit when I was playing around with it.
> 
> That's interesting, but I don't think it's a problem.  Let me know if you think of an issue with it, though.

I figured more than anything I should bring this to your attention in 
case you had not noticed it. Given that you provide an 'ovn-nbctl 
meter-add' command, it strikes me that most people will probably add 
meters this way. If they do it this way, then they won't run into any 
surprises.

> 
> Thanks for checking out the series, and please let me know if you have any other thoughts.
> 
> --Justin
> 
> 



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