Messages in this thread | | | Date | Thu, 6 Mar 2014 06:25:50 -0800 (PST) | From | David Lang <> | Subject | Re: [RFC] [PATCH] Pre-emption control for userspace |
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On Thu, 6 Mar 2014, Kevin Easton wrote:
> On Tue, Mar 04, 2014 at 04:51:15PM -0800, Andi Kleen wrote: >> Anything else? > > If it was possible to make the time remaining in the current timeslice > available to userspace through the vdso, the thread could do something like: > > if (sys_timeleft() < CRITICAL_SECTION_SIZE) > yield(); > lock(); > > to avoid running out of timeslice in the middle of the critical section.
but won't the system call result in context switches? According to Kevin, even a context switch to another thread and back immediatly is bad enough to need to be avoided, so replacing that with the context switch to the kernel and back isn't a subtantial win.
David Lang
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