Messages in this thread | | | Subject | Re: Runtime overhead of PREEMPT_DYNAMIC | From | Mike Galbraith <> | Date | Fri, 20 Oct 2023 16:34:20 +0200 |
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On Fri, 2023-10-20 at 16:11 +0200, Mike Galbraith wrote: > On Fri, 2023-10-20 at 15:40 +0200, Emanuele Rocca wrote: > > Hi Mike, > > > > Here is the full diff between the kernel configurations I used. The only > > change I made was setting CONFIG_PREEMPT_DYNAMIC=n, everything else was > > a consequence of that AFAICT, but please do let me know if you see > > anything that shouldn't be there. > > > > --- config-6.5.0-0.preempt-dynamic-amd64 2023-10-11 15:30:02.000000000 +0200 > > +++ config-6.5.0-0.a.test-amd64 2023-10-11 14:30:02.000000000 +0200 > > > > @@ -10597,7 +10596,6 @@ > > # end of Scheduler Debugging > > > > # CONFIG_DEBUG_TIMEKEEPING is not set > > -CONFIG_DEBUG_PREEMPT=y > > > > # > > # Lock Debugging (spinlocks, mutexes, etc...) > > Seems you had also turned on DEBUG_PREEMPT in the dynamic setup, which > adds some overhead.. but not a metric ton.
Hm, I don't recall the overhead as being that bad, but thar she blows.
i7-4790 avg cmdline 6.5.8-voluntary 3685.08 3679.93 3704.98 3689.99 1.000 6.5.8-dynamic 3571.62 3568.61 3550.55 3563.59 .965 3052.06 3032.74 3019.93 3034.91 .822 +DEBUG_PREEMPT 3651.37 3599.87 3615.18 3622.14 .981 preempt=none 3459.58 3514.09 3539.88 3504.51 .949 preempt=full
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