On Tue, Mar 29 2011 at 3:13pm -0400, Shyam_Iyer@xxxxxxxx <Shyam_Iyer@xxxxxxxx> wrote: > > > > Above is pretty generic. Do you have specific needs/ideas/concerns? > > > > > > > > Thanks > > > > Vivek > > > Yes.. if I limited by Ethernet b/w to 40% I don't need to limit I/O > > b/w via cgroups. Such bandwidth manipulations are network switch driven > > and cgroups never take care of these events from the Ethernet driver. > > > > So if IO is going over network and actual bandwidth control is taking > > place by throttling ethernet traffic then one does not have to specify > > block cgroup throttling policy and hence no need for cgroups to be > > worried > > about ethernet driver events? > > > > I think I am missing something here. > > > > Vivek > Well.. here is the catch.. example scenario.. > > - Two iSCSI I/O sessions emanating from Ethernet ports eth0, eth1 multipathed together. Let us say round-robin policy. > > - The cgroup profile is to limit I/O bandwidth to 40% of the multipathed I/O bandwidth. But the switch may have limited the I/O bandwidth to 40% for the corresponding vlan associated with one of the eth interface say eth1 > > The computation that the bandwidth configured is 40% of the available bandwidth is false in this case. What we need to do is possibly push more I/O through eth0 as it is allowed to run at 100% of bandwidth by the switch. > > Now this is a dynamic decision and multipathing layer should take care of it.. but it would need a hint.. No hint should be needed. Just use one of the newer multipath path selectors that are dynamic by design: "queue-length" or "service-time". This scenario is exactly what those path selectors are meant to address. Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
