Excerpts from Anant Patil's message of 2015-08-30 23:01:29 -0700: > Hi Angus, > > Thanks for doing the tests with convergence. We are now assured that > convergence has not impacted the performance in a negative way. Given > that, in convergence, a stack provisioning process goes through a lot of > RPC calls, it puts a lot of load on the message broker and the request > looses time in network traversal etc., and in effect would hamper the > performance. As the results show, having more than 2 engines will always > yield better results with convergence. Since the deployments usually > have 2 or more engines, this works in favor of convergence. > > I have always held that convergence is more for scale (how much/many) > than for performance (response time), due to it's design of distributing > load (resource provisioning from single stack) among heat engines and > also due to the fact that heat actually spends a lot of time waiting for > the delegated resource request to be completed, not doing much > computation. However, with these tests, we can eliminate any > apprehension of performance issues which would have inadvertently > sneaked in, with our focus more on scalability and reliability, than on > performance. > > I was thinking we should be doing some scale testing where we have many > bigger stacks provisioned and compare the results with legacy, where we > measure memory, CPU and network bandwidth. >
Convergence would be worth it if it was 2x slower in response time, and scaled 10% worse. Because while scalability is super important, the main point is resilience to failure of an engine. Add in engine restarts, failures, etc, to these tests, and I think the advantages will be quite a bit more skewed toward convergence. Really nice work everyone! __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
