On Thu, Jun 08, 2017 at 03:02:43PM +0100, Juri Lelli wrote:
> On 07/06/17 09:14, Byungchul Park wrote:
> > On Wed, Jun 07, 2017 at 08:42:24AM +0900, Byungchul Park wrote:
> > > On Tue, Jun 06, 2017 at 04:12:25PM +0100, Juri Lelli wrote:
> > > > Hi,
> > > >
> > > > On 02/06/17 16:31, Byungchul Park wrote:
>
> [...]
>
> > > > >
> > > > > static inline int cpudl_maximum_cpu(struct cpudl *cp)
> > > > > {
> > > > > - return cp->elements[0].cpu;
> > > > > + int cpu = cp->elements[0].cpu;
> > > > > + return cp->elements[cpu].idx == IDX_INVALID ? -1 : cpu;
> > > >
> > > > Mmm, don't we get a WARN from cpumask_check() if we return -1 here?
> > >
> > > The function does not return -1 without my patch.
> > >
> > > Right?
> >
>
> That's actually my point: with the change you are proposing we will
> start returning -1 and it looks to me that the WARN will start to fire.
Hi,
I see what you talk about. You are talking about WARN in cpumask_check().
Sorry for missing your words.
> What about the below instead (properly splitted in 2 patches I guess,
> and I'm not sure at all the macro thing is pretty at all) ?
>
> --->8---
> kernel/sched/cpudeadline.c | 19 +++++++++++++------
> 1 file changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
> index fba235c7d026..32e3dcef2b81 100644
> --- a/kernel/sched/cpudeadline.c
> +++ b/kernel/sched/cpudeadline.c
> @@ -108,11 +108,17 @@ static void cpudl_heapify(struct cpudl *cp, int idx)
> cpudl_heapify_down(cp, idx);
> }
>
> -static inline int cpudl_maximum(struct cpudl *cp)
> -{
> - return cp->elements[0].cpu;
> +#define cpudl_maximum(field) \
> +static inline int cpudl_maximum_##field \
> +(struct cpudl *cp) \
> +{ \
> + return cp->elements[0].field; \
> }
>
> +cpudl_maximum(cpu);
> +cpudl_maximum(dl);
> +cpudl_maximum(idx);
> +
> /*
> * cpudl_find - find the best (later-dl) CPU in the system
> * @cp: the cpudl max-heap context
> @@ -131,9 +137,10 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
> cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) {
> best_cpu = cpumask_any(later_mask);
> goto out;
> - } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) &&
> - dl_time_before(dl_se->deadline, cp->elements[0].dl)) {
> - best_cpu = cpudl_maximum(cp);
> + } else if (cpudl_maximum_idx(cp) != IDX_INVALID &&
> + cpumask_test_cpu(cpudl_maximum_cpu(cp), &p->cpus_allowed) &&
> + dl_time_before(dl_se->deadline, cpudl_maximum_dl(cp))) {
> + best_cpu = cpudl_maximum_cpu(cp);
This would also work and avoid unnecessary warning. I missed the check
to avoid it. https://lkml.org/lkml/2017/3/23/175 was an original patch
doing it.
By the way, frankly speaking, I don't like accessing the cpudl instant
several times without protection. I rather prefer the following..
But whatever. I like both.
Thnaks,
Byungchul
----->8-----
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index 9b314a9..1d369cf 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -137,11 +137,17 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p,
cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) {
best_cpu = cpumask_any(later_mask);
goto out;
- } else if (cpumask_test_cpu(cpudl_maximum_cpu(cp), &p->cpus_allowed) &&
- dl_time_before(dl_se->deadline, cpudl_maximum_dl(cp))) {
- best_cpu = cpudl_maximum_cpu(cp);
- if (later_mask)
- cpumask_set_cpu(best_cpu, later_mask);
+ } else {
+ int max_cpu = cpudl_maximum_cpu(cp);
+ u64 max_dl = cpudl_maximum_dl(cp);
+
+ if (max_cpu != -1 &&
+ cpumask_test_cpu(max_cpu, &p->cpus_allowed) &&
+ dl_time_before(dl_se->deadline, max_dl)) {
+ best_cpu = max_cpu;
+ if (later_mask)
+ cpumask_set_cpu(best_cpu, later_mask);
+ }
}
out:
