On Tue, Mar 03, 2009 at 01:13:41PM -0700, Alex Williamson wrote: > It seems like something happens around the 5 minute uptime in the guest > that causes virtio-net throughput to plummet. Here's the scenario: > > guest started as: > > taskset -c 4 /usr/local/bin/qemu-system-x86_64 -hda /dev/sdb -m > 2048 -vnc :1 -net nic,macaddr=02:00:10:91:73:02,model=virtio > -net tap,script=$HOME/bin/null-ifup -serial > tcp::1234,server,nowait -mem-path /hugepages/ > > null-ifup looks like this: > > #!/bin/sh > /sbin/ifconfig $1 192.168.0.1 > /sbin/route add -net 192.168.0.0/24 gw 192.168.0.1 > > The guest gets a static IP of 192.168.0.2. > > netserver (part of netperf) in the host is pinned to CPU0, which shares > cache with CPU4 from the above taskset. > > When the guest boots, I run: > > netperf -c -C -H 192.168.0.1 -t TCP_STREAM -- -m 64k > > This results in ~13.5Gbps (note you won't get close to this if you don't > get the tasksets correct) > > Wait 5 minutes, retry. Now I get ~4Gbps. The only way I can get > 13.5Gbps again is by rebooting the guest within the same qemu context, > or of course restarting it completely. > > Any guesses as to what might be going on? Can anyone reproduce? I'm > hoping that I'm doing something dumb, but can't figure out what it is. > The system is running v2.6.29-rc6-121-g64e7130 in the guest, > v2.6.29-rc6-123-gbd7b3b4 on the host, kvm module kvm-84-620-g5bffffc and > userspace kvm-84-95-gea1b668. Thanks, Nope. Collect kvm_stat -l before/after the slowdown? -- 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
