[ovs-discuss] Communicate flow-mod info to kernel module

Jesse Gross jesse at nicira.com
Thu May 29 00:27:22 UTC 2014


On Mon, May 26, 2014 at 5:03 PM, Madhu Challa <challa at noironetworks.com> wrote:
> Jesse,
>
> I ran an iperf test (4 client server pairs) with and without the stats and
> there was no noticeable difference in the measured bandwidth. However as I
> increase the number of connections from 1 to 4 I do see the spin lock
> overhead for this call stack (as a percent of total spin lock overhead on
> the system) go up from 6% to 16%. I have 2 numa nodes on my system and 32
> cores. But yes it is not affecting bandwidth.

Do you notice a difference in the total CPU usage with stats on vs.
off? The significance of the relatively percentage depends on how big
the total spinlock overhead is, presumably.

Also, did you try it with updating last used but not packets/bytes?

Overall, I'm not too excited about going down this path unless there
is a really strong performance justification. The potential to be a
pain in the future seems high...



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