On 10 September 2014 15:50, Peter Zijlstra peterz@infradead.org wrote:
On Sat, Aug 30, 2014 at 10:37:40PM +0530, Preeti U Murthy wrote:
- if ((sd->flags & SD_SHARE_CPUCAPACITY) && weight > 1) {
if (sched_feat(ARCH_CAPACITY))Aren't you missing this check above? I understand that it is not crucial, but that would also mean removing ARCH_CAPACITY sched_feat altogether, wouldn't it?
Yes he's missing that, I added the below bit on top.
FWIW, your changes are fine for me
So the argument last time: lkml.kernel.org/r/20140709105721.GT19379@twins.programming.kicks-ass.net was that you cannot put sched_feat(ARCH_CAPACITY) inside a weak arch_* function. The test has to be outside, seeing how it needs to decide to call the arch function at all (or revert to the default implementation).
--- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5700,7 +5700,7 @@ unsigned long __weak arch_scale_freq_cap return default_scale_capacity(sd, cpu); }
-unsigned long __weak arch_scale_cpu_capacity(struct sched_domain *sd, int cpu) +static unsigned long default_scale_cpu_capacity(struct sched_domain *sd, int cpu) { if ((sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1)) return sd->smt_gain / sd->span_weight; @@ -5708,6 +5708,11 @@ unsigned long __weak arch_scale_cpu_capa return SCHED_CAPACITY_SCALE; }
+unsigned long __weak arch_scale_cpu_capacity(struct sched_domain *sd, int cpu) +{
return default_scale_cpu_capacity(sd, cpu);+}
static unsigned long scale_rt_capacity(int cpu) { struct rq *rq = cpu_rq(cpu); @@ -5747,7 +5752,10 @@ static void update_cpu_capacity(struct s unsigned long capacity = SCHED_CAPACITY_SCALE; struct sched_group *sdg = sd->groups;
capacity *= arch_scale_cpu_capacity(sd, cpu);
if (sched_feat(ARCH_CAPACITY))capacity *= arch_scale_cpu_capacity(sd, cpu);elsecapacity *= default_scale_cpu_capacity(sd, cpu); capacity >>= SCHED_CAPACITY_SHIFT;