Messages in this thread | | | Date | Thu, 26 May 2022 16:32:54 +0800 | Subject | Re: [PATCH] sche/fair: static cpumasks for load balance | From | huangbing <> |
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On 5/26/22 01:04, Peter Zijlstra wrote: > On Mon, May 23, 2022 at 05:42:16PM +0800, Bing Huang wrote: >> The both cpu mask load_balance_mask and select_idle_mask just only used >> in fair.c, but allocation in core.c in CONFIG_CPUMASK_OFFSTACK=y case, >> and global via declare per cpu variations. More or less, it looks wired. >> >> Signed-off-by: Bing Huang <huangbing@kylinos.cn> >> --- >> kernel/sched/core.c | 13 +++---------- >> kernel/sched/fair.c | 18 ++++++++++++++++-- >> kernel/sched/sched.h | 4 ++++ >> 3 files changed, 23 insertions(+), 12 deletions(-) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index d58c0389eb23..64934c5e236d 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -9448,9 +9448,6 @@ LIST_HEAD(task_groups); >> static struct kmem_cache *task_group_cache __read_mostly; >> #endif >> >> -DECLARE_PER_CPU(cpumask_var_t, load_balance_mask); >> -DECLARE_PER_CPU(cpumask_var_t, select_idle_mask); >> - >> void __init sched_init(void) >> { >> unsigned long ptr = 0; >> @@ -9494,14 +9491,10 @@ void __init sched_init(void) >> >> #endif /* CONFIG_RT_GROUP_SCHED */ >> } >> + >> #ifdef CONFIG_CPUMASK_OFFSTACK >> - for_each_possible_cpu(i) { >> - per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( >> - cpumask_size(), GFP_KERNEL, cpu_to_node(i)); >> - per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( >> - cpumask_size(), GFP_KERNEL, cpu_to_node(i)); >> - } >> -#endif /* CONFIG_CPUMASK_OFFSTACK */ >> + init_working_cpumask(); >> +#endif > We already have init_sched_fair_class(), can't you use that?
OK, thanks for your review. I got it.
In addition, I notice that load_balance_mask and select_idle_mask are defined in CONFIG_SMP=y case in fair.c, so could be they moved inside CONFIG_SMP, or just outside ?
> >> >> init_rt_bandwidth(&def_rt_bandwidth, global_rt_period(), global_rt_runtime()); >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index a68482d66535..3a4b0dd1beb5 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -5831,8 +5831,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) >> #ifdef CONFIG_SMP >> >> /* Working cpumask for: load_balance, load_balance_newidle. */ >> -DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); >> -DEFINE_PER_CPU(cpumask_var_t, select_idle_mask); >> +static DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); >> +static DEFINE_PER_CPU(cpumask_var_t, select_idle_mask); >> >> #ifdef CONFIG_NO_HZ_COMMON >> >> @@ -7052,6 +7052,20 @@ balance_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) >> } >> #endif /* CONFIG_SMP */ >> >> +#ifdef CONFIG_CPUMASK_OFFSTACK >> +void __init init_working_cpumask(void) >> +{ >> + int i; >> + >> + for_each_possible_cpu(i) { >> + per_cpu(load_balance_mask, i) = (cpumask_var_t)kzalloc_node( >> + cpumask_size(), GFP_KERNEL, cpu_to_node(i)); >> + per_cpu(select_idle_mask, i) = (cpumask_var_t)kzalloc_node( >> + cpumask_size(), GFP_KERNEL, cpu_to_node(i)); >> + } >> +} >> +#endif > If you stick that #ifdef inside the function, you can remove it > everwhere else. Less #ifdef is more better. I will remove it, move them inside init_sched_fair_class().
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