-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Wireshark was showing a huge amount of invalid packets (wrong checksum) - - that was the cause of the slowdown. Simply rebooting the host into 2.6.28.9 fixed *everything*, regardless of whether the guests use virtio or ne2k_pci/etc. The guests are still running 2.6.29.1, but I am not likely to try that release again on the host anytime soon! Ouch! Antoine Antoine Martin wrote: > Hi, > > I've got some hosts that were happily running the 2.6.25.x host kernel, > kvm-84, kernel.org kvm modules. > The guests were running 2.6.25 to 2.6.29.x quite happily. > Network was using virtio. > Since I upgraded one of the hosts (Intel dual core) to 2.6.29.x > yesterday, the virtio network performance of the guests on it dropped > dramatically. (for some reason another AMD host did not seem to be > affected...) > Here are the tests I performed using wget and scp: > * guest to guest: fast > * guest to host: fast > * host to internet: fast > * guest to internet: slow!!! > I was normally getting ~5MB/s to the host (speed to the internet was > limited by the capacity of the DSL line), but since the upgrade the > performance had dropped to around 20KB/s! > Strangely enough, I could open many new connections to the guest and get > more chunks all at 20KB/s! > I switched the guests to using ne2k_pci and the performance has been > restored... > > And this is where it gets even weirder... > UDP packets get corrupted using ne2k_pci and rtl8139cp but not with > virtio... > So I can get performance or UDP, but not both... > > Let me know if there is anything more I can provide to help fix this > regression. > I can reproduce the problem quite easily without causing problems on the > host. > > Cheers > Antoine > -- > 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 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEUEAREKAAYFAknmb/sACgkQGK2zHPGK1ruzgwCWPMvAJzToIMbrE7k2K2FHBQlk dQCcCpDrTufqIN4ZSQs/dMLTQMYtTAU= =lDW9 -----END PGP SIGNATURE----- -- 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
