From 76748087bfd69ef73b4d39539db00faa37cd4b2c Mon Sep 17 00:00:00 2001 From: Justin Hibbits Date: Thu, 6 Dec 2018 04:36:02 +0000 Subject: [PATCH] powerpc: Set very low priority mode while waiting for AP unleash event The POWER9 does not recognize 'or 27,27,27' as a thread priority NOP. On earlier POWER architectures, this NOP would note to the processor to give up resources if able, to improve performance of other threads. All processors that support the thread priority NOPs recognize the 'or 31,31,31' NOP as very low priority, so use this to perform a similar function, and not burn cycles on POWER9. --- sys/powerpc/powerpc/mp_machdep.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sys/powerpc/powerpc/mp_machdep.c b/sys/powerpc/powerpc/mp_machdep.c index 49e259ad50b..10a87395b3c 100644 --- a/sys/powerpc/powerpc/mp_machdep.c +++ b/sys/powerpc/powerpc/mp_machdep.c @@ -78,7 +78,7 @@ machdep_ap_bootstrap(void) __asm __volatile("msync; isync"); while (ap_letgo == 0) - __asm __volatile("or 27,27,27"); + __asm __volatile("or 31,31,31"); __asm __volatile("or 6,6,6"); /*