Messages in this thread | | | Date | Wed, 13 May 2015 09:52:54 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH 4/5] workqueue: don't expose workqueue_attrs to users |
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Hello, Lai.
On Wed, May 13, 2015 at 09:43:19AM +0800, Lai Jiangshan wrote: > >> I think the workqueue.c has too much complicated and rarely used APIs > >> and exposes too much in this way. No one can set the nice value > >> and the cpuallowed of a task atomically. > > > > What do you mean no one can? > > normal/general task. not kworker. > > no one can set the nice value and the cpumallowed of a normal task atomically. > > The kernel doesn't have such APIs: > > lock_and_get_task_cpus_allowed(task); > /* modify cpumask */ > set_cpus_allowed_ptr_and_unlock();
I'm still not following. What are you trying to say?
> > So, we're now requiring workqueue users to take care of > > synchronization, disabling and reinstating WQ_SYSFS (what if userland > > hits those knobs at the same time?) > > I think there is no userland knobs when !WQ_SYSFS.
So, fail apply attrs calls if the workqueue is exposed to userland? Are you serious?
> > and poking into workqueue struct to determine the current values of the > > I think the copy version of cpumask, nice, numa values are same as > the workqueue struct have. No poking is required. > (Its own lock-protect-region is the ONLY entry to call apply_workqueue_attrs()).
And how would the caller know the current values?
Thanks.
-- tejun
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