Avi Kivity wrote: > On 02/18/2010 11:12 AM, Jan Kiszka wrote: >> Thomas Gleixner wrote: >> >>> The i8254/i8259 locks need to be real spinlocks on preempt-rt. Convert >>> them to raw_spinlock. No change for !RT kernels. >>> >> Last time I ran KVM over RT, I also had to convert requests_lock (struct >> kvm): make_all_cpus_request assumes that this lock prevents migration. >> >> > > True. Will commit something to that effect. > > Meanwhile, if anyone has any idea how to kill this lock, I'd love to see it. > What concurrency does it resolve in the end? On first glance, it only synchronize the fiddling with pre-VCPU request bits, right? What forces us to do this? Wouldn't it suffice to disable preemption (thus migration) and the let concurrent requests race for setting the bits? I mean if some request bit was already set on entry, we don't include the related VCPU in smp_call_function_many anyway. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- 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
