On 10/12/2017 09:57 AM, Byungchul Park wrote: > On Tue, Oct 10, 2017 at 03:44:04PM +0900, Byungchul Park wrote: >> Currently, migrating tasks to cpu0 unconditionally happens when the >> heap is empty, since cp->elements[].cpu was initialized to 0(=cpu0). >> We have to distinguish between the empty case and cpu0 to avoid the >> unnecessary migrantions. Therefore, it has to return an invalid value
s/migrantions/migrations/ ? >> e.i. -1 in that case. > > This patch does what it should obviously do. Could you check this? > >> Signed-off-by: Byungchul Park <[email protected]> >> Acked-by: Steven Rostedt (VMware) <[email protected]> >> --- >> kernel/sched/cpudeadline.c | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c >> index 9f02035..bcf903f 100644 >> --- a/kernel/sched/cpudeadline.c >> +++ b/kernel/sched/cpudeadline.c >> @@ -138,6 +138,12 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, >> int best_cpu = cpudl_maximum_cpu(cp); >> WARN_ON(best_cpu != -1 && !cpu_present(best_cpu)); >> >> + /* >> + * The heap tree is empry for now, just return. s/empry/empty/ ? >> + */ >> + if (best_cpu == -1) >> + return 0; >> + >> if (cpumask_test_cpu(best_cpu, &p->cpus_allowed) && >> dl_time_before(dl_se->deadline, cpudl_maximum_dl(cp))) { >> if (later_mask) >> @@ -265,8 +271,10 @@ int cpudl_init(struct cpudl *cp) >> return -ENOMEM; >> } >> >> - for_each_possible_cpu(i) >> + for_each_possible_cpu(i) { >> + cp->elements[i].cpu = -1; >> cp->elements[i].idx = IDX_INVALID; >> + } >> >> return 0; >> } >> -- >> 1.9.1
