On Thu, May 21, 2015 at 03:51:43PM +0200, Paolo Bonzini wrote: > Some of you may have heard about the "Clear Containers" initiative from > Intel, which couple KVM with various kernel tricks to create extremely > lightweight virtual machines. The experimental Clear Containers setup > requires only 18-20 MB to launch a virtual machine, and needs about 60 > ms to boot. > > Now, as all of you probably know, "QEMU is great for running Windows or > legacy Linux guests, but that flexibility comes at a hefty price. Not > only does all of the emulation consume memory, it also requires some > form of low-level firmware in the guest as well. All of this adds quite > a bit to virtual-machine startup times (500 to 700 milliseconds is not > unusual)". > > Right? In fact, it's for this reason that Clear Containers uses kvmtool > instead of QEMU. > > No, wrong! In fact, reporting bad performance is pretty much the same > as throwing down the gauntlet. > > Enter qboot, a minimal x86 firmware that runs on QEMU and, together with > a slimmed-down QEMU configuration, boots a virtual machine in 40 > milliseconds[2] on an Ivy Bridge Core i7 processor. Hi Paolo, I'm curious if you've tried profiling SeaBIOS to see where it is spending unnecessary time? I wonder if a stripped down SeaBIOS could obtain sufficient performance. The page at http://seabios.org/Debugging#Timing_debug_messages describes how to do basic profiling via timing of debug messages. The default SeaBIOS build takes ~180ms on my (old AMD) system. But, by removing drivers and options via Kconfig I was able to bring it down to ~25ms. I suspect some additional Kconfig settings and a few optimizations would make it possible to significantly reduce this time. Cheers, -Kevin -- 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
