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

[Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

(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.

Thanks,
-Kame


>> +	cpumask_set_cpu(cpu, wq_numa_possible_cpumask[node]);
>> +}
>> +/*
>> + * When a cpu is physically added, cpu<->node relationship is established.
>> + * We can catch the whole view when a new NODE_DATA() coming up.
>> + * Update cpumask used for sched affinity of workers.
>> + */
>> +void workqueue_node_register(int node)
>> +{
>> +	int cpu;
>> +	mutex_lock(&wq_pool_mutex);
>> +	for_each_possible_cpu(cpu) {
>> +		if (node == cpu_to_node(cpu))
>> +			reflesh_wq_possible_mask(cpu, node);
>> +	}
>> +	mutex_unlock(&wq_pool_mutex);
>> +}
>> +
>> +#endif
>>
>>   /*
>>    * Workqueues should be brought up before normal priority CPU notifiers.
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 1bf4807..d0c1ebb 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -1121,6 +1121,10 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
>>   	 * online_pages() and offline_pages().
>>   	 */
>>   	reset_node_present_pages(pgdat);
>> +	/*
>> +	 * Update workqueue's cpu/node affinity info.
>> +	 */
>> +	workqueue_node_register(nid);
>>
>>   	return pgdat;
>>   }
>