Cc: Chuck Ebbert <cebbert@...>, Antoine Martin <antoine@...>, Satyam Sharma <satyam.sharma@...>, Linux Kernel Development <linux-kernel@...>, Peter Zijlstra <a.p.zijlstra@...>, Linus Torvalds <torvalds@...>
Certainly this is reasonable for applications for which the source is
available and readily recompilable. However, there are legacy
closed-source apps out there expecting sched_yield() to result in a
reasonable amount of time passing before the task is scheduled again.
Also, there are installed bases of people that may have older versions
of code that may wish to upgrade to newer kernels without upgrading the
rest of the system. It seems odd to force them to update userspace apps
just because we don't like the undefined semantics.
<snip>
I've always understood one of the kernel's basic tenets to be that we
don't break userspace without a good reason. If there are apps out
there that expect sched_yield() to give up the cpu, it seems
counter-intuitive to ignore that expectation.
Personally, I'd be in favour of making the context-switch be the default
behaviour, but at the very least it should be possible to enable a
"backwards-compatibility mode" for sched_yield().
Chris
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