I haven’t used Xen HVM until recently. When I was at Amazon and
\nhanging with the Xen provisioning folks, I recall complaints about the
\nperformance of network drivers on HVM instances. I’ve recently
\ndiscovered that this was due to the use of the ioemu virtual interface
\n(vif) system. In paravirtualized environments, Xen vif devices are
\nmore efficient because the guest kernel can talk to the hypervisor to
\nschedule I\/O. In hardware virtualized environments, the hypervisor
\nemulates the back end of a common network driver and the guest uses it
\nas if it is the real thing.<\/p>\n
The Xen team (or was it RedHat?) patched the 2.6.18 kernel such that
\nHVM guests got the best of both worlds. The guest ran in a HVM
\nenvironment, but also had a way of talking with the hypervisor by way
\nof the xen-vnif kernel driver
\n(kernel\/drivers\/xenpv_hvm\/netfront\/xen-vnif.ko).<\/p>\n
I may not be looking in the right places, but I can’t seem to find
\nsuch a paravirtualized network driver for any kernels more recent than
\n2.6.18. This has recently become a bit of an issue, since karmic (and probably sid)
\ndepends on udev 145, which depends on signalfd, and thus won’t run on
\nkernels before (something like) 2.6.25.<\/p>\n
Unless I miss my guess (which is quite possible =]), this means one of
\nthe following needs to happen:<\/p>\n
Has this already happened? Am I missing something?<\/p>\n\n