Re: [Xen-devel] [PATCH] xen: Send spinlock IPI to all waiters

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-02-15 at 11:26 +0000, Jan Beulich wrote:
> >>> On 15.02.13 at 12:10, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Fri, 2013-02-15 at 10:52 +0000, Stefan Bader wrote:
> >> diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
> >> index 83e866d..f7a080e 100644
> >> --- a/arch/x86/xen/spinlock.c
> >> +++ b/arch/x86/xen/spinlock.c
> >> @@ -328,7 +328,6 @@ static noinline void xen_spin_unlock_slow(struct 
> > xen_spinlock *xl)
> >>            if (per_cpu(lock_spinners, cpu) == xl) {
> >>                    ADD_STATS(released_slow_kicked, 1);
> >>                    xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
> >> -                  break;
> > 
> > It would be more efficient to build a mask and use xen_send_IPI_mask().
> 
> In order for __xen_send_IPI_mask() to then take the list apart
> again and call xen_send_IPI_one()? There's no batching
> implemented currently...

Oh, I simply assumed it must obviously do that!

Ian.


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