Thanks to reply. Regarding your second question, which flow rules are you asking about?
I just want to know that when ovs had only an in-kernel microflow cache, How many in-kernel cache miss there are, and also how much improving there are when using megaflow. And I have a last question. short-lived flows were main problem when there was micro flow cache. I don't know the circumstance where short lived connection happen often. can you let me know about it? Thanks!! 2017-06-09 13:29 GMT+09:00 Ben Pfaff <b...@ovn.org>: > When OVS had only an in-kernel microflow cache, there were at least two > reasons for performance problems with many short-lived flows. The first > was the cost of sending packets to userspace. The second was the cost > of translating the packets through the entire OpenFlow pipeline. The > megaflow cache solves both problems: it eliminates both the > kernel-to-user-to-kernel transition and (if the megaflow cache is > effective) the additional OpenFlow translations. > > Regarding your second question, which flow rules are you asking about? > > On Fri, Jun 09, 2017 at 12:22:09PM +0900, Heung Sik Choi wrote: > > What does "if only the microflow cache works" mean? > > > > sorry to confuse you. I'm not good at English. > > > > In the paper, the authors say that at start of ovs implementation, there > > has been microflow cache(EMC), but megaflow wasn't implemented. > > > > At that time, they say there was a problem caused by short lived > > connections. > > > > I want to know the problem detail. I guess that the problem made ovs get > > flow rules from userlevel, and that made performance degradation. > > > > also I want to know that when not using megaflow, are there big > difference > > in aspect of number of flow rules.If there are the big difference, can > you > > tell me the difference in numbers? > > > > > > > > 2017-06-09 0:43 GMT+09:00 Ben Pfaff <b...@ovn.org>: > > > > > On Thu, Jun 08, 2017 at 04:33:54PM +0900, Heung Sik Choi wrote: > > > > 1. If only microflow cache works and there are many short lived > > > > connections, does it make many tuples in table, and does it suffers > > > serious > > > > performance degradation by the many tuples(very many tuple makes > context > > > > switching to Userlevel)? > > > > > > What does "if only the microflow cache works" mean? > > > > > > > 2. I know that OVS uses hash for table index. if only microflow > cache and > > > > there are small amount of entries in the table, is it possible to > find > > > > entry in O(1) time? > > > > > > Yes. > > > > > > > 3. In paper, microflow and megaflow use the word 'cache'. However, > when I > > > > open the OVS code, it looks like they are in main memory area. > doesn't > > > the > > > > 'cache' mean hardware cache? > > > > > > No. > > > >
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