On 1/21/14 6:17 PM, "Ben Pfaff" <b...@nicira.com> wrote:
>Please don't drop the mailing list. My apologies for dropping the mailing list. > >I'd expect a dramatic drop in CPU consumption in that case. There are >a few special cases where the upgrade wouldn't help. One is if >in-band control is in use, another is if NetFlow is turned on, a third >is if LACP bonds with L4 port based hashing are turned on, and there >are probably a few others that don't come to mind immediately. I plan to rerun the test to rule out some mistake on my part. Could you provide more information about the nature of the change made in 1.11 that improves performance for this type of traffic? Is the kernel module able to forward UDP DNS packets without sending them to userspace, or was it an optimization of the userspace processing? What roughly is the level of performance I should see? > >Version 2.0 helped with this more, too. > >On Tue, Jan 21, 2014 at 11:14:03PM +0000, McGarvey, Kevin wrote: >> Sorry, I left out details in order to get an answer about whether kernel >> forwarding of single packet flows like this is even possible. >> >> I was initially using the version that ships with RHEL 6.4, but I >>upgraded >> to openvswitch-1.11.0_8ce28d-1.el6ost.x86_64 and upgraded the kernel to >> 2.6.32-358.123.4.openstack.el6.x86_64. I upgraded the kernel first, at >> the recommendation of one of our engineers who has been working a lot >>with >> OpenStack. When that didn't reduce the CPU consumption I upgraded Open >> vSwitch. But I didn't notice a drop in CPU consumption. >> >> Some additional details: >> >> The server is a Dell 710 >> The NICs are Broadcom bcm5709 >> We have 2 bridges configured, one for each NIC >> We are using VLANs >> >> Kevin >> >> On 1/21/14 5:55 PM, "Ben Pfaff" <b...@nicira.com> wrote: >> >> >On Tue, Jan 21, 2014 at 10:50:30PM +0000, McGarvey, Kevin wrote: >> >> I am sending UDP DNS queries to a KVM guest through Open vSwitch >> >> running on the RHEL hypervisor. With traffic of only 5K >> >> request/response pairs per second the CPU consumption of the >> >> ovs-vswitchd process is over 60%. The source IP and port change with >> >> each request, simulating normal UDP DNS traffic. It appears that >> >> each request is being handled as a new flow and is being sent to the >> >> userspace process. When I dump data flows with ovs-dpctl, there are >> >> thousands of flows that are never used. >> >> >> >> Is there a way to get reasonable performance from Open vSwitch with >> >> this type of traffic? I tried adding a flow with ovs-ofctl, >> >> specifying the destination MAC of the guest and everything else >> >> wildcarded, but I saw no change in the CPU consumption of >> >> ovs-vswitchd. >> > >> >You didn't say what version of OVS you're using. The CPU% used for >> >this kind of traffic should drop dramatically with an upgrade to 1.11 >> >or later. >> _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
