Am Montag, den 08.09.2008, 14:07 +0200 schrieb Yann Dupont: > Fabian Deutsch a écrit : > > Hey. > > > > When running a guest in the following setup, I observ a "massive" > > performance decrease after a couple of gigabytes of transfrerred data. > > > > other guests keep running fine (no regressions) and nothing unusual is > > observed on the host. > > > > fedora 8 host, kvm-72 (user and module) > > > > fedora 9 guest, all updates. > > nic 0, vtio: > > subnet a > > samba listening > > > > nic 1, vtio: > > subnet b > > iscsi initiator running > > > > samba shares a mount point, pointing to an iscsi target. > > > > > > now pulling/pushing about 80GB over samba results in a drop from about > > 60/70Mbit to about 1/2Mbit of troughput. > > > > The problem is reproducible. > > The problem is solved after a reboot of the guest. Just restarting > > networking doesn't help. > > Guest's dmesg doesn't say anything about problems. No errors in > > ifconfig. > > > > Has someone observed something similar? > > > > > > Greetings > > - fabian > > > > -- > > To unsubscribe from this list: send the line "unsubscribe kvm" in > > the body of a message to [EMAIL PROTECTED] > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > We just saw the very same issue. > guest & host : 2.6.25.3, debian etch 64 bits > > KVM 70 on this machine. > > As fabian said, rebooting the kernel doesn't help, but rebooting the > whole kvm guest does. > > No error messages as far as I can tell. The kvm guest is a clonezilla > server and send lots of data. > It began to crawl after 2/3 weeks of usage.
Are you also using model=vortio? If so, you might want to switch to e1000. Less performance but stable. The issues seems to be related to virtio/tap. And a little bit more to the tap itnerface/implementation, because of the reboot-observation. fabian -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
