On Fri, Jan 18, 2019 at 03:32:34PM +0530, Viresh Kumar wrote: > On 17-01-19, 17:03, Matthias Kaehlcke wrote: > > On Fri, Jan 11, 2019 at 02:48:34PM +0530, Viresh Kumar wrote: > > > +static void fcs_update(struct freq_constraints *fcs, struct freq_pair > > > *freq, > > > + enum fc_event event) > > > +{ > > > + mutex_lock(&fcs->lock); > > > + > > > + if (_fcs_update(fcs, freq, event)) { > > > + if (fcs->callback) > > > + schedule_work(&fcs->work); > > > > IIUC the constraints aren't applied until the callback is executed. I > > wonder if a dedicated workqueue should be used instead of the system > > one, to avoid longer delays from other kernel entities that might > > 'misbehave'. Especially for thermal constraints we want a quick > > response. > > I thought the system workqueue should be fast enough, it contains > multiple threads which can all run in parallel and service this work.
Ok, I was still stuck at the old one thread per CPU model, where a slow work would block other items in the same workqueue until it finishes execution. After reading a bit through Documentation/core-api/workqueue.rst I agree that a system workqueue is probably fast enough. It might be warranted though to use system_highpri_wq here. Cheers Matthias