Messages in this thread | | | Date | Mon, 14 Oct 2013 16:10:47 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] mm: Set N_CPU to node_states during boot |
| |
On Mon, 14 Oct 2013 14:04:56 -0600 Toshi Kani <toshi.kani@hp.com> wrote:
> After a system booted, N_CPU is not set to any node as has_cpu > shows an empty line. > > # cat /sys/devices/system/node/has_cpu > (show-empty-line) > > setup_vmstat() registers its CPU notifier callback, > vmstat_cpuup_callback(), which marks N_CPU to a node when > a CPU is put into online. However, setup_vmstat() is called > after all CPUs are launched in the boot sequence. > > Change setup_vmstat() to mark N_CPU to the nodes with online > CPUs at boot. > > ... > > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -1276,8 +1276,10 @@ static int __init setup_vmstat(void) > > register_cpu_notifier(&vmstat_notifier); > > - for_each_online_cpu(cpu) > + for_each_online_cpu(cpu) { > start_cpu_timer(cpu); > + node_set_state(cpu_to_node(cpu), N_CPU); > + } > #endif > #ifdef CONFIG_PROC_FS > proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
This seems a bit hacky. Would it not be better to register vmstat_notifier() before bringing up CPUs?
And this patch might be racy as well - what happens if a CPU comes up and goes down again before setup_vmstat() is called?
(Where does N_CPU get cleared? It doesn't, afaict. Should we clear it if a node's final CPU goes offline?)
| |