On Fri, Jul 31, 2026 at 7:03 AM Christophe Leroy (CS GROUP) <[email protected]> wrote: > > > > Le 30/07/2026 à 19:10, Shrikanth Hegde a écrit : > > Hi Jirka, Paul, > > > > > > +cc will > > > > On 7/30/26 8:38 PM, Jirka Hladky wrote: > >> On Thu, Jul 30, 2026 at 4:53 PM Paul E. McKenney <[email protected]> > >> wrote: > >>> But is this really a fundamental RISC cost? For example, does arm64 > >>> see the same performance issues? > >> > >> We tested arm64 (Ampere Altra Max) with the same controlled > >> experiment -- two 6.18 kernels, both voluntary, differing only in > >> PREEMPT_DYNAMIC: > >> > >> Arch PREEMPT_DYNAMIC kill bogo-ops/sec Delta > >> ------- --------------- ----------------- ----- > >> ppc64le off 108,836 > >> ppc64le on 68,197 -37.3% > >> aarch64 off 5,538 > >> aarch64 on 5,082 -8.2% > >> > >> arm64 sees -8.2% vs ppc64le's -37.3%. So arm64 is affected but > >> much less severely. > > > > Ouch!. But that's good to know. > > Might be a stupid question, but what is your .config ? > Are you sure it doesn't contain CONFIG_DEBUG_PREEMPT ?
I have double-checked that and it's not set: # CONFIG_DEBUG_PREEMPT is not set Thanks Jirka
