Messages in this thread | | | Date | Fri, 19 Dec 2014 20:56:23 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] tick/powerclamp: Remove tick_nohz_idle abuse |
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On Fri, 19 Dec 2014, Jacob Pan wrote:
> On Thu, 18 Dec 2014 22:12:57 +0100 (CET) > Thomas Gleixner <tglx@linutronix.de> wrote: > > > On Thu, 18 Dec 2014, Jacob Pan wrote: > > > OK I agree, also as I mentioned earlier, Peter already has a patch > > > for consolidated idle loop and remove tick_nohz_idle_enter/exit > > > call from powerclamp driver. I have been working on a few tweaks to > > > maintain the functionality and efficiency with the consolidated > > > idle loop. We can apply the patches on top of yours. > > > > No. This is equally wrong as I pointed out before. The 'unified' idle > > loop is still fake and just pretending to be idle. > > > In terms of efficiency, the consolidated idle loop will allow turning > off sched tick during idle injection period. If we just take out the > tick_nohz_idle_xxx call, the effectiveness of powerclamp is going down > significantly. I am not arguing the design but from fixing regression > perspective or short term solution.
There is no perspective. Period.
Its violates every rightful assumption of the nohz_IDLE_* code and just ever worked by chance. There is so much subtle wreckage lurking there that the only sane solution is to forbid it. End of story.
Thanks,
tglx
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