On Tue, Oct 10, 2023 at 12:32:22PM +0200, Emanuele Rocca wrote: > On 2023-10-10 12:14, Johannes Schauer Marin Rodrigues wrote: > > Quoting Emanuele Rocca (2023-10-10 12:10:07) > > > Setting CONFIG_HAVE_PREEMPT_DYNAMIC=y on arm64 is likely safe for us too, > > > but > > > we may want to run some benchmark first to see if there are any noticeable > > > slowdowns. > > > > I have a couple of arm64 boards here that I can run benchmarks on. What > > would > > you recommend to run to test the effect of CONFIG_HAVE_PREEMPT_DYNAMIC=y? > > I'm not sure what the best benchmark would be, but maybe you could start > with something generic like timing a kernel build with and without > PREEMPT_DYNAMIC and throwing 'hey' at your favorite web server? > https://github.com/rakyll/hey
Whatever you do, check whether having a serial console still works with that setting. I had trouble with that in kernel 6.5, had some fruitless discussions on the LKML and developer interest abruptly died when I found out that the bug I encountered could be worked around by having those settings: [1/4998]mh@fan:~ $ grep PREEMPT /boot/config-6.5.6-zgws1 CONFIG_PREEMPT_BUILD=y # CONFIG_PREEMPT_NONE is not set CONFIG_PREEMPT_VOLUNTARY=y # CONFIG_PREEMPT is not set CONFIG_PREEMPT_COUNT=y CONFIG_PREEMPTION=y CONFIG_PREEMPT_DYNAMIC=y CONFIG_PREEMPT_RCU=y CONFIG_HAVE_PREEMPT_DYNAMIC=y CONFIG_HAVE_PREEMPT_DYNAMIC_CALL=y CONFIG_PREEMPT_NOTIFIERS=y CONFIG_DRM_I915_PREEMPT_TIMEOUT=640 CONFIG_DRM_I915_PREEMPT_TIMEOUT_COMPUTE=7500 # CONFIG_DEBUG_PREEMPT is not set # CONFIG_PREEMPT_TRACER is not set # CONFIG_PREEMPTIRQ_DELAY_TEST is not set Greetings Marc -- ----------------------------------------------------------------------------- Marc Haber | "I don't trust Computers. They | Mailadresse im Header Leimen, Germany | lose things." Winona Ryder | Fon: *49 6224 1600402 Nordisch by Nature | How to make an American Quilt | Fax: *49 6224 1600421
