Messages in this thread | | | Subject | Re: [RFC 09/16] kgr: mark task_safe in some kthreads | From | Mike Galbraith <> | Date | Thu, 15 May 2014 07:04:22 +0200 |
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On Thu, 2014-05-15 at 00:50 -0400, Tejun Heo wrote: > Hello, Mike. > > On Thu, May 15, 2014 at 06:46:18AM +0200, Mike Galbraith wrote: > > > I think it'd be healthier to identify the use cases and then provide > > > proper interface for it. Note that workqueue can now expose interface > > > to modify concurrency, priority and cpumask to userland which > > > writeback workers are already using. > > > > You can't identify a specific thing, any/all of it can land on the > > user's diner plate, so he should be able to make the decisions. Power > > to the user and all that, if he does something stupid, tuff titty. User > > getting to call the shots, and getting to keep the pieces when he fscks > > it all up is wonderful stuff, lets kernel people off the hook :) > > Do we know specific kthreads which need to be exposed with this way?
Soft/hard irq threads and anything having to do with IO mostly, which including workqueues. I had to give the user a rather fugly global prioritization option to let users more or less safely do the evil deeds they want to and WILL do whether I agree with their motivation to do so or not. I tell all users that realtime is real dangerous, but if they want to do that, it's their box, so by definition perfectly fine.
> If there are good enough reasons for specific ones, sure, but I don't > think "we can't change any of the kthreads because someone might be > diddling with it" is something we can sustain in the long term.
I think the opposite. Taking any control the user has is pure evil.
-Mike
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