Messages in this thread | | | Date | Wed, 7 Apr 2021 11:54:37 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3] sched/fair: bring back select_idle_smt, but differently |
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On Wed, Apr 07, 2021 at 11:42:17AM +0200, Vincent Guittot wrote: > I would really prefer to keep that out of select_idle_cpu which aims to merge in one > single loop the walk through sd_llc. In the case of select_idle_smt, this is done outside > the loop:
Fair enough.
> @@ -6317,11 +6339,21 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) > } > } > > + if (static_branch_likely(&sched_smt_present)) { > + smt = test_idle_cores(target, false); > + if (!smt && cpus_share_cache(prev, target)) { > + /* No idle core. Check if prev has an idle sibling. */ > + i = select_idle_smt(p, sd, prev); > + if ((unsigned int)i < nr_cpumask_bits) > + return i; > + } > + } > + > sd = rcu_dereference(per_cpu(sd_llc, target)); > if (!sd) > return target;
It needs to be here, otherwise you're using @sd uninitialized.
> - i = select_idle_cpu(p, sd, target); > + i = select_idle_cpu(p, sd, smt, target); > if ((unsigned)i < nr_cpumask_bits) > return i;
Let me have another poke at it.
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