On Fri, Dec 04, 2015 at 09:02:26AM +0100, Ingo Molnar wrote: > > * Tejun Heo <[email protected]> wrote: > > > Hello, Ulrich. > > > > On Thu, Dec 03, 2015 at 03:12:20PM -0500, Ulrich Obergfell wrote: > > > I share Don's concern about connecting the soft lockup detector and the > > > workqueue watchdog to the same kernel parameter in /proc. I would feel > > > more comfortable if the workqueue watchdog had its dedicated parameter. > > > > Sure, separating the knobs out isn't difficult. I still don't like > > the idea of having multiple set of similar knobs controlling about the > > same thing tho. > > > > For example, let's say there's a user who boots with "nosoftlockup" > > explicitly. I'm pretty sure the user wouldn't be intending to keep > > workqueue watchdog running. The same goes for threshold adjustments, > > so here's my question. What are the reasons for the concern? What > > are we worrying about? > > As Don mentioned it already, we went through similar arguments (and pain) > with the > hard/soft lockup detectors and its various control knobs, it would be better > to > have new control knobs separated. > > As for the ease of use argument, we can add a new, obviously named control > knob > that controls _all_ lockup detectors: > > boot param: nolockupdetectors > matching Kconfig knob: CONFIG_BOOTPARAM_NO_LOCKUP_DETECTORS=0 > > but please don't artificially couple the control knobs of these various > lockup > detectors, as these internal assumptions are less than obvious to users. With > (effectively) 4 lockup detectors such coupling of interfaces is even more > confusing and damaging.
It might be worth tying them together with a generic knob and expanding the bit mask for the 'watchdog' variable. I can't figure out an easy way to do that right now. I don't think we want to go down the route of 'registering' detectors yet. :-) Cheers, Don -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
