On Tue, Aug 20, 2013 at 11:51:23AM +0800, Chen Gang wrote:
>
>
> If 'hc' is false, 'al' will never be false, either (only need check
> "irdp->qlen != rdp->qlen_lazy' when 'rdp->nxtlist' existance).
>
> Recommend to improve the related code, like the diff below.
Are you sure that this represents an improvement? If so, why?
Or to put it another way, I see a patch that increases the size of the
kernel by three lines. What is the corresponding benefit given common
kernel workloads?
Thanx, Paul
> ----------------------------------diff
> begin------------------------------------
>
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 5b53a89..421caf0 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -2719,10 +2719,13 @@ static int rcd'_cpu_has_callbacks(int cpu, bool
> *all_lazy)
>
> for_each_rcu_flavor(rsp) {
> rdp = per_cpu_ptr(rsp->rda, cpu);
> - if (rdp->qlen != rdp->qlen_lazy)
> - al = false;
> - if (rdp->nxtlist)
> + if (rdp->nxtlist) {
> hc = true;
> + if (rdp->qlen != rdp->qlen_lazy) {
> + al = false;
> + break;
> + }
> + }
> }
> if (all_lazy)
> *all_lazy = al;
>
> ----------------------------------diff
> end--------------------------------------
>
>
> On 08/20/2013 11:50 AM, Chen Gang wrote:
> > According to the comment above rcu_cpu_has_callbacks(): "If there are
> > no callbacks, all of them are deemed to be lazy".
> >
> > So when both 'hc' and 'al' are false, '*all_lazy' should be true, not
> > false.
> >
> >
> > Signed-off-by: Chen Gang <[email protected]>
> > ---
> > kernel/rcutree.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> > index 5b53a89..9ee9565 100644
> > --- a/kernel/rcutree.c
> > +++ b/kernel/rcutree.c
> > @@ -2725,7 +2725,7 @@ static int rcu_cpu_has_callbacks(int cpu, bool
> > *all_lazy)
> > hc = true;
> > }
> > if (all_lazy)
> > - *all_lazy = al;
> > + *all_lazy = !hc ? true : al;
> > return hc;
> > }
> >
> >
>
>
> --
> Chen Gang
>
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