> > > > Please consider s390 and (x86/arm) KVM. Once we have a few, more can > > > > follow later, but I think its important to not only have PPC support for > > > > this. > > > > > > Actually the s390 preemted check via sigp sense running is available for > > > all hypervisors (z/VM, LPAR and KVM) which implies everywhere as you can > > > no longer buy s390 systems without LPAR. > > > > > > As Heiko already pointed out we could simply use a small inline function > > > that calls cpu_is_preempted from arch/s390/lib/spinlock (or > > > smp_vcpu_scheduled from smp.c) > > > > Sure, and I had vague memories of Heiko's email. This patch set however > > completely fails to do that trivial hooking up. > > sorry for that. > I will try to work it out on x86. x86 has no hypervisor support, and I'd like to understand the desired semantics first, so I don't think it should block this series. In particular, there are at least the following choices: 1) exit to userspace (5-10.000 clock cycles best case) counts as lock holder preemption 2) any time the vCPU thread not running counts as lock holder preemption To implement the latter you'd need a hypercall or MSR (at least as a slow path), because the KVM preempt notifier is only active during the KVM_RUN ioctl. Paolo _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
