Re: [PATCH 08/11] cpuset: separate configured masks and efffectivemasks

[Tejun Heo]

Hello, Li.

On Fri, Aug 23, 2013 at 03:46:47PM +0800, Li Zefan wrote:
> On 2013/8/21 22:08, Tejun Heo wrote:
> > On Wed, Aug 21, 2013 at 06:00:42PM +0800, Li Zefan wrote:
> >> @@ -2261,7 +2271,8 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
> >>  	/* synchronize mems_allowed to N_MEMORY */
> >>  	if (mems_updated) {
> >>  		mutex_lock(&callback_mutex);
> >> -		top_cpuset.mems_allowed = new_mems;
> >> +		if (!sane)
> >> +			top_cpuset.mems_allowed = new_mems;
> > 
> > Can you please further explain how the top cgroup behaves?
> > 
> 
> top_cpuset.cpus_allowed will always be cpu_active_mask if sane_behavior
> is not set, otherwise it will always be cpu_possible_mask. While
> top_cpuset.effective_cpus will always be cpu_active_mask in either
> case.

Just in case it wasn't clear, it'd be great if you can also explain
what's going on w.r.t. sane_behavior in the comments and patch
description.  Having dual modes of operation can always be quite
confusing so I think some documentation could be very beneficial.

Thanks!

-- 
tejun
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