On Thu, Mar 17, 2016 at 12:19:44PM +0800, Zhao Lei wrote: > +static u64 __cpuusage_read(struct cgroup_subsys_state *css, > + enum cpuacct_usage_index index) > { > struct cpuacct *ca = css_ca(css); > u64 totalcpuusage = 0; > int i; > > for_each_present_cpu(i) > + totalcpuusage += cpuacct_cpuusage_read(ca, i, index); > > return totalcpuusage; > }
Ok, so while looking over this, it mostly uses for_each_present_cpu(), which is already dubious, but then cpuacct_stats_show() uses for_each_online_cpu(). Why is this? Why not always for_each_possible_cpu()? Surely, if you offline a cpu, you still want its stat to be included in your totals, otherwise your numbers will go backwards when you take a cpu offline. Could you double check the logic and maybe fix? Thanks!