On Thu, 9 May 2013 12:43:20 -0700
Chegu Vinod <chegu_vi...@hp.com> wrote:
> If a user chooses to turn on the auto-converge migration capability
> these changes detect the lack of convergence and throttle down the
> guest. i.e. force the VCPUs out of the guest for some duration
> and let the migration thread catchup and help converge.
>
[...]
> +
> +static void mig_delay_vcpu(void)
> +{
> + qemu_mutex_unlock_iothread();
> + g_usleep(50*1000);
> + qemu_mutex_lock_iothread();
> +}
> +
> +/* Stub used for getting the vcpu out of VM and into qemu via
> + run_on_cpu()*/
> +static void mig_kick_cpu(void *opq)
> +{
> + mig_delay_vcpu();
> + return;
> +}
> +
> +/* To reduce the dirty rate explicitly disallow the VCPUs from spending
> + much time in the VM. The migration thread will try to catchup.
> + Workload will experience a performance drop.
> +*/
> +void migration_throttle_down(void)
> +{
> + if (throttling_needed()) {
> + CPUArchState *penv = first_cpu;
> + while (penv) {
> + qemu_mutex_lock_iothread();
Locking it here and the unlocking it inside of queued work doesn't look nice.
What exactly are you protecting with this lock?
> + async_run_on_cpu(ENV_GET_CPU(penv), mig_kick_cpu, NULL);
> + qemu_mutex_unlock_iothread();
> + penv = penv->next_cpu;
> + }
> + }
> +}
--
Regards,
Igor
