On 03/05/13 11:43, Stefano Stabellini wrote: > On Thu, 2 May 2013, Christopher Covington wrote: >>> So the virtual timer should appear to have been running even while time >>> is being stolen and therefore stolen time needs to be accounted via some >>> other means. >> >> Something that's not currently obvious to me is that given that the stolen >> cycle accounting should be done, what makes the architected timer interrupt >> handler the ideal place to do it? > > That is a good question and I would appreciate suggestions to improve > the patch. > > Given that Xen x86 and ia64 does stolen time accounting from the timer > interrupt handler: > > arch/x86/xen/time.c:xen_timer_interrupt > arch/ia64/kernel/time.c:timer_interrupt > > and given that the arch_timer is the only timer used by Xen on ARM and > that it includes a virt_timer that is made on purpose to be used by > virtual machines, I thought that it might be a good place for it. > > I also thought that doing it this way, KVM should be able to reuse the > same hook.
Indeed. I just need to understand how time stealing works there ;-). Now, KVM is not necessarily limited to arch_timers, and we've run KVM using a QEMU-provided timer in the past. Can you think of a more generic location for this hook? Possibly something that would satisfy the requirements of other architectures while we're at it? M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/