Re: disabling group leader perf_event

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> No, I want the ability to terminate the code at any time and clean up 
> any resources used.  We have exactly the same requirements for ordinary 
> userspace.

So you intend to prevent its use at any point where we have a kernel only
resource held in any way manner or form ? Remember we don't hold locks or
many kinds of kernel resource across syscalls. Likewise I'm interested
how you will keep it compatible with real time ?

> > - bounded memory use
> > - trustable behaviour for access
> 
> Right.
> 
> > and usually minimal side effects since you want to optimise very
> > heavily and side effects stop that (which is also why Fortran still kicks
> > C's backside for crunching)
> >
> > Not sure you need/want to do the conversion in kernel.
> 
> I prefer bytecode as well.
> 
> > I'd have thought a
> > sane way to handle it would have been to throw stuff at the kernel in
> > some kind of semi-sane byte code that can be interpreted by a noddy
> > interpreter but firstly when you get it have the kernel try and run a
> > helper to compile it.
> 
> So you do want to jit?

Depends what you mean by jit. JIT normally implies compiling/recompiling
as you go. Do we want to compile it once at load time - probably,
assuming the tool is present.