On Mon, Apr 30, 2012 at 12:19:26PM +0200, Sebastien Estienne wrote: > Hi Pasi, > > Do you know if ubuntu 12.04 has these optimized drivers or not? >
I think Canonical developers are going to add the drivers later in some update to Ubuntu 12.04 packages. The drivers are not yet in 12.04. I saw some discussion from Canonical guys on xen-devel about that. -- Pasi > thanx > > -- > Sebastien E. > > > Le 30 avr. 2012 à 11:06, Pasi Kärkkäinen <pa...@iki.fi> a écrit : > > > On Sun, Apr 29, 2012 at 06:18:52PM +0200, Willy Tarreau wrote: > >> > >>> I'm using VPS machines from Linode.com, they are quite powerful. They're > >>> based on Xen. I don't see the network card saturated. > >> > >> OK I see now. There's no point searching anywhere else. Once again you're > >> a victim of the high overhead of virtualization that vendors like to > >> pretend > >> is almost unnoticeable :-( > >> > >>> As for nf_conntrack, I have iptables enabled with rules as a firewall on > >>> each machine, I stopped it on all involved machines and I still get those > >>> results. nf_conntrack is compiled to the kernel (it's a kernel provided by > >>> Linode) so I don't think I can disable it completely. Just not use it (and > >>> not use any firewall between them). > >> > >> It's having the module loaded with default settings which is harmful, so > >> even unloading the rules will not change anything. Anyway, now I'm pretty > >> sure that the overhead caused by the default conntrack settings is nothing > >> compared with the overhead of Xen. > >> > >>> Even if 6-7K is very low (for nginx directly), why is haproxy doing half > >>> than that? > >> > >> That's quite simple : it has two sides so it must process twice the number > >> of packets. Since you're virtualized, you're packet-bound. Most of the time > >> is spent communicating with the host and with the network, so the more the > >> packets and the less performance you get. That's why you're seeing a 2x > >> increase even with nginx when enabling keep-alive. > >> > >> I'd say that your numbers are more or less in line with a recent benchmark > >> we conducted at Exceliance and which is summarized below (each time the > >> hardware was running a single VM) : > >> > >> > >> http://blog.exceliance.fr/2012/04/24/hypervisors-virtual-network-performance-comparison-from-a-virtualized-load-balancer-point-of-view/ > >> > >> (BTW you'll note that Xen was the worst performer here with 80% loss > >> compared to native performance). > >> > > > > Note that Ubuntu 11.10 kernel is lacking important drivers such as the > > Xen ACPI power management / cpufreq drivers so it's not able to use the > > better performing CPU states. That driver is merged to recent upstream > > Linux 3.4 (-rc). > > Also the xen-netback dom0 driver is still unoptimized in the upstream Linux > > kernel. > > > > Using RHEL5/CentOS5 as Xen host/dom0, or SLES11 or OpenSuse is a better > > idea today > > for benchmarking because those have the "fully optimized" kernel/drivers. > > Upstream Linux will get the optimizations in small steps (per the Linux > > development model). > > > > Citrix XenServer 6 is using the optimized kernel/drivers so that explains > > the difference > > in the benchmark compared to Ubuntu Xen4.1. > > > > I just wanted to hilight that. > > > > -- Pasi > > > >
