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. I > > > 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. It'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). The 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, > this is effectively the same as one of my hacks to the datapath > that I mentioned in an earlier mail. The result is that eth1 > "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. > 3) 2) + place a tc egress filter on eth1 > > Which mostly makes sense to me although I am a little confused about > why 1) needs a filter on dummy0 (a filter on eth1 has no effect) > but 3) needs a filter on eth1 (a filter on dummy0 has no effect, > even if the skb is sent to dummy0 last. > > I also had some limited success using CPU cgroups, though obviously > that targets CPU usage and thus the effect on throughput is fairly course. > In short, its a useful technique but not one that bares further > discussion here. > > -- > 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 > -- 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
