Messages in this thread | | | From | Nick Piggin <> | Subject | Re: [PATCH 6/6] sched: disabled rt-bandwidth by default | Date | Tue, 19 Aug 2008 21:17:51 +1000 |
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On Tuesday 19 August 2008 21:05, Ingo Molnar wrote: > * Peter Zijlstra <a.p.zijlstra@chello.nl> wrote: > > Disable bandwidth control by default. > > > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> > > --- > > kernel/sched.c | 17 +++++++---------- > > 1 file changed, 7 insertions(+), 10 deletions(-) > > > > Index: linux-2.6/kernel/sched.c > > =================================================================== > > --- linux-2.6.orig/kernel/sched.c > > +++ linux-2.6/kernel/sched.c > > @@ -824,9 +824,9 @@ static __read_mostly int scheduler_runni > > > > /* > > * part of the period that we allow rt tasks to run in us. > > - * default: 0.95s > > + * default: inf > > */ > > -int sysctl_sched_rt_runtime = 950000; > > +int sysctl_sched_rt_runtime = -1; > > The fixes look good to me, but this enabling of infinite RT task lockups > is not an improvement. > > The thing is, i got far more bugreports about locked up RT tasks where > the lockup was unintentional, than real bugreports about anyone > _intending_ for the whole box to come to a grinding halt because a > high-prio RT tasks is monopolizing the CPU.
Why are all these people running poorly written apps then?
We don't cater to poorly at the expense of the properly written code.
> In fact there's only been this artificial test so far.
No, someone reported that it broke their app.
> So could you please just increase the chunking to 10 seconds or so, from > the current 1 second? Anyone locking up the system for more than 10 > seconds via an RT task has to deal with many other issues already. > > I.e. keep the system borderline debuggable (up to 10 seconds delays are > _not_ nice so people will notice) - but it's still a marked improvement > from completly locked up desktops. > > And those who really need longer than 10 second periods can set it > higher, or even (if they want to live dangerously or run POSIX > conformance tests) make it infinite (set it to -1) - and will have to > deal with other things like the softlockup watchdog as well. > > Ok?
Nack. Let's retain our API specifications and backwards compatibilty by default. Advertise the sysrq switch and the setting of the sysctl to throttle, but don't break this by default please.
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