Re: [PATCH V9] workqueue: Allow modifying low level unbound workqueue cpumask

[Tejun Heo <tj@kernel.org>]

On Thu, Apr 30, 2015 at 05:16:12PM +0800, Lai Jiangshan wrote:
> Allow to modify the low-level unbound workqueues cpumask through
> sysfs. This is performed by traversing the entire workqueue list
> and calling apply_wqattrs_prepare() on the unbound workqueues
> with the new low level mask. Only after all the preparation are done,
> we commit them all together.
> 
> Ordered workqueues are ignored from the low level unbound workqueue
> cpumask, it will be handled in near future.
> 
> All the (default & per-node) pwqs are mandatorily controlled by
> the low level cpumask. If the user configured cpumask doesn't overlap
> with the low level cpumask, the low level cpumask will be used for the
> wq instead.
> 
> The comment of wq_calc_node_cpumask() is updated and explicitly
> requires that its first argument should be the attrs of the default
> pwq.
> 
> The default wq_unbound_cpumask is cpu_possible_mask.  The workqueue
> subsystem doesn't know its best default value, let the system manager
> or the other subsystem set it when needed.
> 
> Changed from V8:
>   merge the calculating code for the attrs of the default pwq together.
>   minor change the code&comments for saving the user configured attrs.
>   remove unnecessary list_del().
>   minor update the comment of wq_calc_node_cpumask().
>   update the comment of workqueue_set_unbound_cpumask();
> 
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Kevin Hilman <khilman@linaro.org>
> Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
> Cc: Mike Galbraith <bitbucket@online.de>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Viresh Kumar <viresh.kumar@linaro.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Original-patch-by: Frederic Weisbecker <fweisbec@gmail.com>
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>

Applied to wq/for-4.2 and yeah the prepare function looks better now.

Thanks a lot for the persistence.

-- 
tejun