[Cbe-oss-dev] [PATCH 2/2] spufs: Remove spurious WARN_ON for spu_deactivate for NOSCHED contexts

[Arnd Bergmann]

On Tuesday 17 July 2007, Jeremy Kerr wrote:
> > It was introduced for isolated  tasks, which simply break if you try
> > to read the registers. 
> 
> Then we make the register accesses conditional on !ISOLATE, rather 
> than !NOSCHED.

But that would be doing the opposite of what we created the NOSCHED
flag for in the first place. The idea was to minimize the difference
between an ISOLATE thread and a regular one running without the
ISOLATE flag, but splitting the isolation into the NOSCHED property,
which makes the kernel behave differently regarding scheduling and
debuggability, and the actual ISOLATE flag that only changes how
the hardware acts and how it interfaces to the kernel.

> However, the main problem is that we'd need to implement the reservation 
> scheme - and that requires time :D

Given unlimited time, I'd rather have an implementation of isolated
threads without relying on NOSCHED. That would make fewer people
rely on the odd behaviour of NOSCHED rather than adding more
complexity to it.

	Arnd <><