On 11/27/24 12:14, Christophe Leroy wrote:
Le 25/11/2024 à 05:22, Shrikanth Hegde a écrit :
Once the lazy preemption is supported, it would be desirable to change
the preemption models at runtime. So this change adds support for dynamic
preemption using DYNAMIC_KEY.
In irq-exit to kernel path, use preempt_model_preemptible for decision.
Other way would be using static key based decision. Keeping it
simpler since key based change didn't show performance improvement.
What about static_call, wouldn't it improve performance ?
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 6d6bbd93abab..01c58f5258c9 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -270,6 +270,7 @@ config PPC
select HAVE_PERF_EVENTS_NMI if PPC64
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
+ select HAVE_PREEMPT_DYNAMIC_KEY
Can you use HAVE_PREEPT_DYNAMIC_CALL instead ? That should be more
performant.
I know static calls are not in for PPC64 yet, you can restart from
http://patchwork.ozlabs.org/project/linuxppc-dev/
cover/20221010002957.128276-1-bg...@linux.ibm.com/ and https://
github.com/linuxppc/issues/issues/416
Thanks Christophe, I will take a look and understand.
May be stupid question, do the concerns of arm still valid for ppc64/ppc32
out-line static calls?
https://lore.kernel.org/all/20220214165216.2231574-6-mark.rutl...@arm.com/
As I understood, that is the reason they went ahead with DYNAMIC_KEY.
Christophe
