On Fri, Apr 6, 2012 at 2:25 PM, Masoud Moshref Javadi <masood.moshre...@gmail.com> wrote: > On 4/6/2012 9:20 AM, Jesse Gross wrote: >> >> On Thu, Apr 5, 2012 at 7:16 PM, Masoud Moshref Javadi >> <masood.moshre...@gmail.com> wrote: >>> >>> I have the following experiment and whenever I check ovs-dpctl >>> dump-flows, >>> it gives me less than 7k entries: >>> There are three machines A,B, and C. B runs openvswitch and connect the >>> other two. A and B send 10k packets each second from different flows to >>> the >>> other node. I don't use TCP so there is no ack. There should be 20k >>> entries >>> there after a second but I get at most 7k and the value changes. It seems >>> that the facet cache cannot hold enough facets, so it replaces them so >>> often. The high cpu usage for ovs-vswitchd process also confirms this >>> claim >>> that the cache cannot hold all entries. >> >> As I said before, userspace generally tries to keep the number of >> flows installed in the kernel to a few thousand to avoid maintenance >> overhead. The contents of the kernel flow cache is an implementation >> detail and there's no requirement that it hold everything. If you >> want to try different values you can set flow-eviction-threshold in >> the config database. > > > Thank you. > Now suppose that because of this maintenance process and the large number of > active flows we need to go to the userspace so often and this makes high CPU > usage. What will happen to the packets if the machine cannot handle them > with 100% CPU. Is there any DropTail queue there?
There's a queue from kernel to userspace. If the buffer size is exceeded then packets will be dropped. _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
