[ovs-discuss] ovsdb behavior under ovn management plane scaling

[Han Zhou]

On Thu, Jan 28, 2016 at 2:39 PM, Andy Zhou <azhou at ovn.org> wrote:

>
>
> On Thu, Jan 28, 2016 at 2:31 PM, Russell Bryant <russell at ovn.org> wrote:
>
>> On 01/28/2016 05:25 PM, Andy Zhou wrote:
>> >
>> >
>> > On Thu, Jan 28, 2016 at 11:35 AM, Ryan Moats <rmoats at us.ibm.com
>> > <mailto:rmoats at us.ibm.com>> wrote:
>> >
>> >     As promised on today's OVN IRC meeting...
>> >
>> >     We're in the process of testing OVN at scale as well as looking at
>> >     the performance of the various planes of OVN.
>> >
>> >     One of the initial management plane scaling tests is to
>> >
>> >     1. Create OpenStack external etwork x1 with IPv4 subnet xs1 (we
>> >     aren't testing the data plane, so we don't have to worry about NAT)
>> >     2. Replicate the following template 400 times
>> >     a. Create OpenStack project p(i) and then in p(i):
>> >     b. create a network n1 and assign an IPv4 subnet s1 to it
>> >     c. create a router, assign an interface to s1 and set the router's
>> >     external gateway to xs1
>> >     d. launch a compute instance i1, attached to n1
>> >
>> >     [in a network line diagram: i1 -- n1(s1) -- r1 -- x1(xs1)]
>> >
>> >     When doing this with on a four VM cloud (each VM has four CPU cores
>> >     and 16 GB of memory), we are seeing the steps "assign an interface
>> >     to s1" and "set the router's external gateway to xs1" take longer
>> >     amounts of time as the number of templates increases.
>> >
>> >     Looking at the ovsdb server logs during this test, one can break
>> >     down OVN_Northbound operations into three buckets:
>> >     (1) pure insert operations
>> >     (2) operations that combine and insert and an update
>> >     (3) pure update operations
>> >
>> >     Data from buckets (1) and (2) were combined and plotted in
>> >     http://ibin.co/2V2VVrQYDKyI - The vertical axis is in seconds, and
>> >     the horizontal axis is "transaction during the test", so while I
>> >     can't tell you exactly where in the test a particular point
>> >     occurred, one can look at the graph and say with some level
>> >     of confidence that inserting rows into a table isn't all that
>> >     expensive an operation.
>> >
>> >     Data from bucket (3) was plotted as http://ibin.co/2V2Vjb9rVqUK -
>> >     Again, the vertical axis is in seconds, and the horizontal axis is
>> >     "transaction during the test". All of these operations are updates
>> >     to port state in the Logical_Ports table and I read this plot as
>> >     saying that as we have more and more ports in the Logical_Ports
>> >     table, update operations can take longer and longer. Given the OVN
>> >     scale I am looking at (the current test cloud is 125 hypervisors),
>> >     any linearity in time (even via increased variability) is something
>> >     I'd like to see if we can improve...
>> >
>> >  Thanks for sharing the data.  The master branch supports "monitor2" and
>> > "update2"  JSONRPC messages. Do you know if they are being used?
>>
>> That's the default unless you explicitly turn it off, right?
>>
>> Yes for C IDL. "monitor" is still supported.  Just want to confirm.
>
>>
>>
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I don't think monitor2 is being used now by networking-ovn plugin,
otherwise we would not hit the ovsdb problem earlier caused by mixed
monitor & mintor2 caches.

-- 
Best regards,
Han
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