Re: [PATCH 3/4] workqueue: Update workqueue's possible cpumask when a new node, coming up.

Kamezawa Hiroyuki
2014-12-16T08:18:28Z

(2014/12/16 17:10), Kamezawa Hiroyuki wrote:
> (2014/12/16 16:49), Lai Jiangshan wrote:
>> On 12/15/2014 07:18 PM, Kamezawa Hiroyuki wrote:
>>> Workqueue keeps cpu<->node relationship including all possible cpus.
>>> The original information was made at boot but it may change when
>>> a new node is added.
>>>
>>> Update information if a new node is ready with using node-hotplug callback.
>>>
>>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>>> ---
>>> include/linux/memory_hotplug.h | 2 ++
>>> kernel/workqueue.c | 28 +++++++++++++++++++++++++++-
>>> mm/memory_hotplug.c | 4 ++++
>>> 3 files changed, 33 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
>>> index 8f1a419..cd3cb67 100644
>>> --- a/include/linux/memory_hotplug.h
>>> +++ b/include/linux/memory_hotplug.h
>>> @@ -270,4 +270,6 @@ extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
>>> extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
>>> unsigned long pnum);
>>>
>>> +/* update for workqueues */
>>> +void workqueue_node_register(int node);
>>> #endif /* __LINUX_MEMORY_HOTPLUG_H */
>>> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
>>> index 2fd0bd7..5499b76 100644
>>> --- a/kernel/workqueue.c
>>> +++ b/kernel/workqueue.c
>>> @@ -266,7 +266,7 @@ struct workqueue_struct {
>>> static struct kmem_cache *pwq_cache;
>>>
>>> static cpumask_var_t *wq_numa_possible_cpumask;
>>> - /* possible CPUs of each node */
>>> + /* PL: possible CPUs of each node */
>>>
>>> static bool wq_disable_numa;
>>> module_param_named(disable_numa, wq_disable_numa, bool, 0444);
>>> @@ -4559,6 +4559,32 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
>>> WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
>>> pool->attrs->cpumask) < 0);
>>> }
>>> +#ifdef CONFIG_MEMORY_HOTPLUG
>>> +
>>> +static void reflesh_wq_possible_mask(int cpu, int node)
>>> +{
>>> + int oldnode;
>>> + for_each_node_state(oldnode, N_POSSIBLE)
>>> + cpumask_clear_cpu(cpu, wq_numa_possible_cpumask[oldnode]);
>>
>> You need to check and update all the wq->numa_pwq_tbl[oldnode]
>>
>
> you mean : if I drop patch 1/4, it will be required. Right ?
> I'll add that check.

Ah, isn't it handled by wq_update_unbound_numa() called at workqueue_cpu_down_callback() ?
Because node's online cpumask will be empty, new pwq will be attached.

Thanks
-Kame