[ovs-discuss] If ovs doesn't masking process in flow_tbl_lookup, What are the disadvantages ?

Heung Sik Choi hschoi at os.korea.ac.kr
Fri Jun 9 03:22:09 UTC 2017


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 <blp at 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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