Re: [PATCH 6/6] sched: disabled rt-bandwidth by default

[Mark Hounschell]

Thomas Gleixner wrote:
> On Tue, 26 Aug 2008, Nick Piggin wrote:
>
> > On Tuesday 26 August 2008 19:30, Ingo Molnar wrote:
> > > * Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
> > > > So... no reply to this? I'm really wondering how it's OK to break
> > > > documented standards and previous Linux behaviour by default for
> > > > something that it is trivial to solve in userspace? [...]
> > > I disagree
> > Your arguments were along the line of:
> >
> > * It probably doesn't break anything (except we had somebody report
> >   that it breaks their app)
>
> I'm a real-time oldtimer. An application which hogs the CPU for 9.9
> seconds with SCHED_FIFO priority is just broken. It's broken beyond
> all limits, whether POSIX allows to do that or Linux obeyed the
> request of the braindamaged application design.

Well, I've been working on RT hardware (mostly) and software since 1977.
With all due respect, thats crapola. I for one have this requirement and
there is _no_ way around it in my world. In fact it's the kernel thats broke
by stealing precious usecs from me.

> From my point of view, as an RT user, any kernel that supports SMP yet can't 
guarantee me %100 of even one _my_ processors is just a plainly broken kernel. 

> > * If it does break something then they must be doing something stupid
> >   (I refuted that because there are several legitimate ways to use rt
> >   scheduling that is broken by this)
> >
> > * We have many other APIs and tools that don't conform to posix (why
> >   is that a reason to break this one?)
>
> Simply because we use common sense instead of following every single
> POSIX brainfart by the letter.
>
> > * We should break the API to cater for stupid users and distros who
> >   create local DoS and/or lock up their boxes (except this is trivial
> >   to solve by setting sysctls or having a watchdog or using sysrq)
>
> For the vast majority of users and RT developers a sane default of
> sanity measures is useful and sensible. 
>
> If someone wants to shoot himself in the foot then it's not an
> unreasonable request that he needs to disable the safety guards before
> pulling the trigger.

Again that is also crapola. If i want to shoot myself in the foot, it's
none of your concern. I know perfectly well what will happen when 
I pull the trigger. 

My 2 cents
Regards
Mark
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