* Re: [Question or BUG] [NUMA]: I feel puzzled at the function cpumask_of_node
[not found] <5937C608.7010905@huawei.com>
@ 2017-06-08 14:12 ` Michal Hocko
[not found] ` <20170608141214.GJ19866-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
0 siblings, 1 reply; 2+ messages in thread
From: Michal Hocko @ 2017-06-08 14:12 UTC (permalink / raw)
To: Leizhen (ThunderTown)
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Catalin Marinas,
Will Deacon, linux-arm-kernel, linux-mm, linux-kernel,
chenchunxiao, x86l, linux-api
[CC linux-api]
On Wed 07-06-17 17:23:20, Leizhen (ThunderTown) wrote:
> When I executed numactl -H(print cpumask_of_node for each node), I got
> different result on X86 and ARM64. For each numa node, the former
> only displayed online CPUs, and the latter displayed all possible
> CPUs. Actually, all other ARCHs is the same to ARM64.
>
> So, my question is: Which case(online or possible) should function
> cpumask_of_node be? Or there is no matter about it?
Unfortunatelly the documentation is quite unclear
What: /sys/devices/system/node/nodeX/cpumap
Date: October 2002
Contact: Linux Memory Management list <linux-mm@kvack.org>
Description:
The node's cpumap.
not really helpeful, is it? Semantically I _think_ printing online cpus
makes more sense because it doesn't really make much sense to bind
anything on offline nodes. Generic implementtion of cpumask_of_node
indeed provides only online cpus. I haven't checked specific
implementations of arch specific code but listing offline cpus sounds
confusing to me.
--
Michal Hocko
SUSE Labs
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Question or BUG] [NUMA]: I feel puzzled at the function cpumask_of_node
[not found] ` <20170608141214.GJ19866-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
@ 2017-06-15 2:00 ` Leizhen (ThunderTown)
0 siblings, 0 replies; 2+ messages in thread
From: Leizhen (ThunderTown) @ 2017-06-15 2:00 UTC (permalink / raw)
To: Michal Hocko
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Catalin Marinas,
Will Deacon, linux-arm-kernel, linux-mm, linux-kernel,
chenchunxiao, x86l, linux-api-u79uwXL29TY76Z2rM5mHXA
On 2017/6/8 22:12, Michal Hocko wrote:
> [CC linux-api]
>
> On Wed 07-06-17 17:23:20, Leizhen (ThunderTown) wrote:
>> When I executed numactl -H(print cpumask_of_node for each node), I got
>> different result on X86 and ARM64. For each numa node, the former
>> only displayed online CPUs, and the latter displayed all possible
>> CPUs. Actually, all other ARCHs is the same to ARM64.
>>
>> So, my question is: Which case(online or possible) should function
>> cpumask_of_node be? Or there is no matter about it?
>
> Unfortunatelly the documentation is quite unclear
> What: /sys/devices/system/node/nodeX/cpumap
> Date: October 2002
> Contact: Linux Memory Management list <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>
> Description:
> The node's cpumap.
>
> not really helpeful, is it? Semantically I _think_ printing online cpus
> makes more sense because it doesn't really make much sense to bind
> anything on offline nodes. Generic implementtion of cpumask_of_node
> indeed provides only online cpus. I haven't checked specific
> implementations of arch specific code but listing offline cpus sounds
> confusing to me.
>
OK, thank you very much. So, how about we directly add "cpumask_and with cpu_online_mask", as below:
diff --git a/drivers/base/node.c b/drivers/base/node.c
index b10479c..199723d 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -28,12 +28,14 @@ static struct bus_type node_subsys = {
static ssize_t node_read_cpumap(struct device *dev, bool list, char *buf)
{
struct node *node_dev = to_node(dev);
- const struct cpumask *mask = cpumask_of_node(node_dev->dev.id);
+ struct cpumask mask;
+
+ cpumask_and(&mask, cpumask_of_node(node_dev->dev.id), cpu_online_mask);
/* 2008/04/07: buf currently PAGE_SIZE, need 9 chars per 32 bits. */
BUILD_BUG_ON((NR_CPUS/32 * 9) > (PAGE_SIZE-1));
- return cpumap_print_to_pagebuf(list, buf, mask);
+ return cpumap_print_to_pagebuf(list, buf, &mask);
}
static inline ssize_t node_read_cpumask(struct device *dev,
--
Thanks!
BestRegards
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2017-06-08 14:12 ` [Question or BUG] [NUMA]: I feel puzzled at the function cpumask_of_node Michal Hocko
[not found] ` <20170608141214.GJ19866-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2017-06-15 2:00 ` Leizhen (ThunderTown)
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