Hi Pasi, Do you know if ubuntu 12.04 has these optimized drivers or not?
thanx -- Sebastien E. Le 30 avr. 2012 à 11:06, Pasi Kärkkäinen <[email protected]> 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 > >
