Re: [PATCH 2/5] xen: events: Make last processed event channel a per-cpu variable.

[Ian Campbell <Ian.Campbell@eu.citrix.com>]

On Wed, 2011-03-09 at 20:32 +0000, Konrad Rzeszutek Wilk wrote:
> On Thu, Mar 03, 2011 at 05:10:12PM +0000, Ian Campbell wrote:
> > Signed-off-by: Ian Campbell <ian.campbell@xensource.com>
> > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> 
> You cloned yourself?

The first is from the original linux-2.6.18-xen.hg commit.

The second is from today as I forward the change upstream.

I wasn't really sure what to do with the historical signed-off-by so I
decided to leave it, just as I would have done if it had been someone
else's.

Ian.

> 
> > [ijc: forward ported from linux-2.6.18-xen.hg 325:b2768401db94]
> > ---
> >  drivers/xen/events.c |   13 ++++++-------
> >  1 files changed, 6 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> > index 75cc6f5..1fc3192 100644
> > --- a/drivers/xen/events.c
> > +++ b/drivers/xen/events.c
> > @@ -1026,6 +1026,8 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
> >  }
> >  
> >  static DEFINE_PER_CPU(unsigned, xed_nesting_count);
> > +static DEFINE_PER_CPU(unsigned int, last_word_idx) = { BITS_PER_LONG - 1 };
> > +static DEFINE_PER_CPU(unsigned int, last_bit_idx) = { BITS_PER_LONG - 1 };
> >  
> >  /*
> >   * Mask out the i least significant bits of w
> > @@ -1043,8 +1045,6 @@ static DEFINE_PER_CPU(unsigned, xed_nesting_count);
> >   */
> >  static void __xen_evtchn_do_upcall(void)
> >  {
> > -	static unsigned int last_word_idx = BITS_PER_LONG - 1;
> > -	static unsigned int last_bit_idx = BITS_PER_LONG - 1;
> >  	int word_idx, bit_idx;
> >  	int cpu = get_cpu();
> >  	struct shared_info *s = HYPERVISOR_shared_info;
> > @@ -1065,8 +1065,8 @@ static void __xen_evtchn_do_upcall(void)
> >  #endif
> >  		pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
> >  
> > -		word_idx = last_word_idx;
> > -		bit_idx = last_bit_idx;
> > +		word_idx = __this_cpu_read(last_word_idx);
> > +		bit_idx = __this_cpu_read(last_bit_idx);
> >  
> >  		while (pending_words != 0) {
> >  			unsigned long pending_bits;
> > @@ -1121,9 +1121,8 @@ static void __xen_evtchn_do_upcall(void)
> >  				 * If this is the final port processed, we'll
> >  				 * pick up here+1 next time.
> >  				 */
> > -				last_word_idx = word_idx;
> > -				last_bit_idx = bit_idx;
> > -
> > +				__this_cpu_write(last_word_idx, word_idx);
> > +				__this_cpu_write(last_bit_idx, bit_idx);
> >  			} while (bit_idx != BITS_PER_LONG - 1);
> >  
> >  			pending_bits = active_evtchns(cpu, s, word_idx);
> > -- 
> > 1.5.6.5
> > 
> > 
> > _______________________________________________
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> > http://lists.xensource.com/xen-devel