From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Leizhen (ThunderTown)" Subject: Re: [Question or BUG] [NUMA]: I feel puzzled at the function cpumask_of_node Date: Thu, 15 Jun 2017 10:00:25 +0800 Message-ID: <5941EA39.8090501@huawei.com> References: <5937C608.7010905@huawei.com> <20170608141214.GJ19866@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170608141214.GJ19866-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org 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@public.gmane.org List-Id: linux-api@vger.kernel.org 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 > 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