Messages in this thread |  | | Subject | Re: [RESEND PATCH] sched/fair: consider RT/IRQ pressure in select_idle_sibling | From | Rohit Jain <> | Date | Fri, 9 Feb 2018 14:05:17 -0800 |
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On 02/09/2018 07:46 AM, Dietmar Eggemann wrote: > On 02/09/2018 01:53 PM, Peter Zijlstra wrote: >> On Mon, Jan 29, 2018 at 03:27:09PM -0800, Rohit Jain wrote: > > [...] > >>> @@ -6173,8 +6183,15 @@ static int select_idle_cpu(struct task_struct >>> *p, struct sched_domain *sd, int t >>> return -1; >>> if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) >>> continue; >>> + if (idle_cpu(cpu)) { >>> + if (full_capacity(cpu)) { >>> + best_cpu = cpu; >>> + break; >>> + } else if (capacity_of(cpu) > best_cap) { >>> + best_cap = capacity_of(cpu); >>> + best_cpu = cpu; >>> + } >>> + } >> >> No need for the else. And you'll note you're once again inconsistent >> with your previous self. >> >> But here I worry about big.little a wee bit. I think we're allowed big >> and little cores on the same L3 these days, and you can't directly >> compare capacity between them. >> >> Morten / Dietmar, any comments? > > Yes, for DynamIQ (big.little successor) systems, those cpus can have > different capacity_orig_of() values already. >
OK, given that there are asymmetric capacities in L3 cores, we would probably have something like the below(?) in select_idle_cpu:
if (!cpumask_test_cpu(cpu, &p->cpus_allowed)) continue; + if (idle_cpu(cpu) && !reduced_capacity(cpu)) + break;
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