On 2020-12-21 16:35, Bjorn Andersson wrote:
On Thu 17 Dec 12:49 CST 2020, Alex Elder wrote:
On 12/17/20 12:21 PM, rishabhb@xxxxxxxxxxxxxx wrote:
> On 2020-12-17 08:12, Alex Elder wrote:
> > On 12/15/20 4:55 PM, Bjorn Andersson wrote:
> > > On Sat 12 Dec 14:48 CST 2020, Rishabh Bhatnagar wrote:
> > >
> > > > Create an unbound high priority workqueue for recovery tasks.
> >
> > I have been looking at a different issue that is caused by
> > crash notification.
> >
> > What happened was that the modem crashed while the AP was
> > in system suspend (or possibly even resuming) state. And
> > there is no guarantee that the system will have called a
> > driver's ->resume callback when the crash notification is
> > delivered.
> >
> > In my case (in the IPA driver), handling a modem crash
> > cannot be done while the driver is suspended; i.e. the
> > activities in its ->resume callback must be completed
> > before we can recover from the crash.
> >
> > For this reason I might like to change the way the
> > crash notification is handled, but what I'd rather see
> > is to have the work queue not run until user space
> > is unfrozen, which would guarantee that all drivers
> > that have registered for a crash notification will
> > be resumed when the notification arrives.
> >
> > I'm not sure how that interacts with what you are
> > looking for here. I think the workqueue could still
> > be unbound, but its work would be delayed longer before
> > any notification (and recovery) started.
> >
> > -Alex
> >
> >
> In that case, maybe adding a "WQ_FREEZABLE" flag might help?
Yes, exactly. But how does that affect whatever you were
trying to do with your patch?
I don't see any impact on Rishabh's change in particular, syntactically
it would just be a matter of adding another flag and the impact would
be
separate from his patch.
In other words, creating a separate work queue to get the long running
work off the system_wq and making sure that these doesn't run during
suspend & resume seems very reasonable to me.
The one piece that I'm still contemplating is the HIPRIO, I would like
to better understand the actual impact - or perhaps is this a result of
everyone downstream moving all their work to HIPRIO work queues,
starving the recovery?
Hi Bjorn,
You are right, this is a result of downstream having HIPRIO workqueues
therefore starving recovery. I don't have actual data to support the
flag
as of now. If needed for now we can skip this flag and add it later with
sufficient data?
Regards,
Bjorn
