Re: [Xen-devel] [PATCH 1/5] xen: use masking operation instead of test_bit for RTDS bits

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 02/10/15 05:40, Juergen Gross wrote:
> Use a bit mask for testing of a set bit instead of test_bit in case no
> atomic operation is needed, as this will lead to smaller and more
> effective code.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>

> ---
>  xen/common/sched_rt.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/common/sched_rt.c b/xen/common/sched_rt.c
> index 4b5c5e4..6a341b1 100644
> --- a/xen/common/sched_rt.c
> +++ b/xen/common/sched_rt.c
> @@ -931,7 +931,7 @@ rt_vcpu_sleep(const struct scheduler *ops, struct vcpu 
> *vc)
>          cpu_raise_softirq(vc->processor, SCHEDULE_SOFTIRQ);
>      else if ( __vcpu_on_q(svc) )
>          __q_remove(svc);
> -    else if ( test_bit(__RTDS_delayed_runq_add, &svc->flags) )
> +    else if ( svc->flags & RTDS_delayed_runq_add )
>          clear_bit(__RTDS_delayed_runq_add, &svc->flags);
>  }
>  
> @@ -1064,7 +1064,7 @@ rt_vcpu_wake(const struct scheduler *ops, struct vcpu 
> *vc)
>       * the Runqueue/DepletedQ. Instead, we set a flag so that it will be
>       * put on the Runqueue/DepletedQ after the context has been saved.
>       */
> -    if ( unlikely(test_bit(__RTDS_scheduled, &svc->flags)) )
> +    if ( unlikely(svc->flags & RTDS_scheduled) )
>      {
>          set_bit(__RTDS_delayed_runq_add, &svc->flags);
>          return;
> 


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