On 18-10-22 19:15:16, Peter Zijlstra wrote: > > Firstly, who come a patch that is grubbing around in kernel/locking/ has > an x86/hyperv subject and isn't Cc'ed to the locking maintainers? > I am sorry. That is my fault to forget to add locking maintainers.
> On Mon, Oct 22, 2018 at 12:31:45PM -0400, Waiman Long wrote: > > On 10/22/2018 03:32 AM, Juergen Gross wrote: > > > On 22/10/2018 03:53, Yi Sun wrote: > > >> On 18-10-19 16:20:52, Juergen Gross wrote: > > >>> On 19/10/2018 15:13, Yi Sun wrote: > > >> [...] > > >> > > >>>> diff --git a/kernel/locking/qspinlock_paravirt.h > > >>>> b/kernel/locking/qspinlock_paravirt.h > > >>>> index 0130e48..9e88c7e 100644 > > >>>> --- a/kernel/locking/qspinlock_paravirt.h > > >>>> +++ b/kernel/locking/qspinlock_paravirt.h > > >>>> @@ -7,6 +7,8 @@ > > >>>> #include <linux/bootmem.h> > > >>>> #include <linux/debug_locks.h> > > >>>> > > >>>> +#include <asm/mshyperv.h> > > >>>> + > > >>>> /* > > >>>> * Implement paravirt qspinlocks; the general idea is to halt the > > >>>> vcpus instead > > >>>> * of spinning them. > > >>>> @@ -305,6 +307,10 @@ static void pv_wait_node(struct mcs_spinlock > > >>>> *node, struct mcs_spinlock *prev) > > >>>> wait_early = true; > > >>>> break; > > >>>> } > > >>>> +#if defined(CONFIG_X86_64) && defined(CONFIG_PARAVIRT_SPINLOCKS) && > > >>>> IS_ENABLED(CONFIG_HYPERV) > > >>>> + if (!hv_notify_long_spin_wait(SPIN_THRESHOLD - > > >>>> loop)) > > >>>> + break; > > >>>> +#endif > > Secondly; how come you thought that was acceptable in any way shape or > form? > Sorry for that. Will try another way. > > > vcpu_is_preempted() is already part of this loop. And this is a paravirt > > > hook. Can't you make use of that? This might require adding another > > > parameter to this hook, but I'd prefer that over another pv-spinlock > > > hook. > > > I agree with Juergen on that. I would suggest rename the > > vcpu_is_preempted hook into a more generic vcpu_stop_spinning, perhaps, > > so different hypervisors can act on the information accordingly. Adding > > an extra parameter is fine. > > No; no extra parameters. vcpu_is_preempted() is a simple and intuitive > interface. Why would we want to make it complicated?
