Re: [PATCH] syscall latency improvement #1

[Alan Cox]

> NOTE! There are potentially other ways to do all of this, _without_ losing
> atomicity. For example, you can move the "flags" value into the slot saved
> for the CS segment (which, modulo vm86, will always be at a constant
> offset on the stack), and make CS=0 be the work flag. That will cause the
> CPU to trap atomically at the "iret".

Is the test even needed. Suppose we instead patch the return stack if we
set need_resched/sigpending, and do it on the rare occassion we set the
value.