Messages in this thread | | | From | Fredrik Markström <> | Date | Mon, 22 May 2017 15:07:12 +0200 | Subject | Core isolation, cpu hotplug and stop_machine |
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Hello,
As I understand it the recommended way to force pending timers of a core when trying to isolate it (runtime) is to use cpu hotplug. The current implementation of cpu hotplug has a serious drawback in that it uses stop_machine() which disturbs already isolated cores. This is a serious problem in our usecase.
I would guess we are not the only ones with this problem, but as far as I can see there is currently no solution for this in the latest next. There was a patchset back in 2013 that implemented stop_machine-free hotplug, but that was never accepted. (https://lwn.net/Articles/538819/)
So is there any ongoing work to solve this problem and what is the preferred way to solve it, is it:
1) stop_machine() free hotplug. It seems to be quite complex but probably solves more problems then the one above. 2) Invent some new mechanism/interface separate from hotplug to migrate timers and hrtimers. 3) Don't, because this isn't a use-case that linux should support.
/Fredrik
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