On Thu, Jun 16, 2011 at 8:24 AM, Ingo Molnar <mingo@xxxxxxx> wrote: > - executing AIO in the vcpu thread eats up precious vcpu execution > time: combined QCOW2 throughput would be limited by a single > core's performance, and any time spent on QCOW2 processing would > not be spent running the guest CPU. (In such a model we certainly > couldnt do more intelligent, CPU-intense storage solutions like on > the fly compress/decompress of QCOW2 data.) This has been a problem in qemu-kvm. io_submit(2) steals time from the guest (I think it was around 20us on the system I measured last year). Add the fact that the guest kernel might be holding a spinlock and it becomes a scalability problem for SMP guests. Anything that takes noticable CPU time should be done outside the vcpu thread. Stefan -- 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
