Re: [Xen-devel] Bug report and patch about IRQ freezing after gic_restore_state

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2013-05-21 at 11:13 +0000, ììì wrote:
> > > Signed-off-by: Jaeyong Yoo 
> > > --- 
> > >  xen/arch/arm/domain.c |    4 ++-- 
> > >  xen/arch/arm/gic.c    |    4 ++-- 
> > >  2 files changed, 4 insertions(+), 4 deletions(-) 
> > > diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c 
> > > index f71b582..2c3b132 100644 
> > > --- a/xen/arch/arm/domain.c 
> > > +++ b/xen/arch/arm/domain.c 
> > > @@ -141,6 +141,8 @@ static void ctxt_switch_to(struct vcpu *n) 
> > >      /* VGIC */ 
> > >      gic_restore_state(n); 
> > > +    local_irq_enable(); 
> > > +
> > 
> > Could you move the local_irq_enable right after ctxt_switch_to?
> 
> Of course.
> Just one small concern:
> Would it be more efficient (i.e., less scheduling latency) if we
> enable irq right after gic_restore state similar to lock-breaking
> effect?

Perhaps, but I think at this stage we should aim for obvious
correctness.

Optimising things for IRQ/scheduler latency is a complete project in its
own right.

Ian.


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