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

[Russell Bryant]

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?

-- 
Russell Bryant