On Thu, Jan 13, 2011 at 10:45:38AM -0500, Jesse Gross wrote: > On Thu, Jan 13, 2011 at 1:47 AM, Simon Horman <horms@xxxxxxxxxxxx> wrote: > > On Mon, Jan 10, 2011 at 06:31:55PM +0900, Simon Horman wrote: > >> On Fri, Jan 07, 2011 at 10:23:58AM +0900, Simon Horman wrote: > >> > On Thu, Jan 06, 2011 at 05:38:01PM -0500, Jesse Gross wrote: > >> > > >> > [ snip ] > >> > > > >> > > I know that everyone likes a nice netperf result but I agree with > >> > > Michael that this probably isn't the right question to be asking. ÂI > >> > > don't think that socket buffers are a real solution to the flow > >> > > control problem: they happen to provide that functionality but it's > >> > > more of a side effect than anything. ÂIt's just that the amount of > >> > > memory consumed by packets in the queue(s) doesn't really have any > >> > > implicit meaning for flow control (think multiple physical adapters, > >> > > all with the same speed instead of a virtual device and a physical > >> > > device with wildly different speeds). ÂThe analog in the physical > >> > > world that you're looking for would be Ethernet flow control. > >> > > Obviously, if the question is limiting CPU or memory consumption then > >> > > that's a different story. > >> > > >> > Point taken. I will see if I can control CPU (and thus memory) consumption > >> > using cgroups and/or tc. > >> > >> I have found that I can successfully control the throughput using > >> the following techniques > >> > >> 1) Place a tc egress filter on dummy0 > >> > >> 2) Use ovs-ofctl to add a flow that sends skbs to dummy0 and then eth1, > >> Â Âthis is effectively the same as one of my hacks to the datapath > >> Â Âthat I mentioned in an earlier mail. The result is that eth1 > >> Â Â"paces" the connection. > > > > Further to this, I wonder if there is any interest in providing > > a method to switch the action order - using ovs-ofctl is a hack imho - > > and/or switching the default action order for mirroring. > > I'm not sure that there is a way to do this that is correct in the > generic case. It's possible that the destination could be a VM while > packets are being mirrored to a physical device or we could be > multicasting or some other arbitrarily complex scenario. Just think > of what a physical switch would do if it has ports with two different > speeds. Yes, I have considered that case. And I agree that perhaps there is no sensible default. But perhaps we could make it configurable somehow? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
