On Thu, Nov 10, 2011 at 10:20:24AM +0900, Simon Horman wrote: > On Wed, Nov 09, 2011 at 01:19:42PM -0800, Ben Pfaff wrote: > > On Mon, Nov 07, 2011 at 04:20:19PM +0900, Simon Horman wrote: > > > Although a very simple and possibly na??ve approach, I wonder if > > > dynamically extending the interval at which statistics are collected is > > > a worthwhile approach to mitigating the performance impact of statistics > > > collection. > > > > It's one approach. It has the nice property of being very simple. > > > > Another approach that I've been pondering myself is, when there are many > > datapath flows, to read out the kernel stats for only some of them at a > > time and apply the expiration algorithm to just those. We could run > > expiration just as frequently overall, but it would apply to any given > > flow less frequently. > > I had also considered that and I think it an approach worth investigating. > It seems to me that the main challenge will be arrange things such that a > partial statistics update can occur while still allowing all statistics to > be updated over time. I wonder if partitioning the flow hash would be a > reasonable way to achieve this.
I think that it works OK already. Just start the flow dump and read as many flows as you want to deal with at a time, then stop, keeping the dump in progress. Then when you want to keep going later, just keep reading the dump. I'd have to go look for the exact behavior when the flow table resizes (perhaps some flows would be lost or seen twice?), but I'm not sure that those are a big deal. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
