The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ac9816dcbab53c57bcf1d7b15370b08f1e284318 Mon Sep 17 00:00:00 2001
From: Akshay Adiga akshay.adiga@linux.vnet.ibm.com Date: Wed, 16 May 2018 17:32:14 +0530 Subject: [PATCH] powerpc/powernv/cpuidle: Init all present cpus for deep states
Init all present cpus for deep states instead of "all possible" cpus. Init fails if a possible cpu is guarded. Resulting in making only non-deep states available for cpuidle/hotplug.
Stewart says, this means that for single threaded workloads, if you guard out a CPU core you'll not get WoF (Workload Optimised Frequency), which means that performance goes down when you wouldn't expect it to.
Fixes: 77b54e9f213f ("powernv/powerpc: Add winkle support for offline cpus") Cc: stable@vger.kernel.org # v3.19+ Signed-off-by: Akshay Adiga akshay.adiga@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c index 1f12ab1e6030..1c5d0675b43c 100644 --- a/arch/powerpc/platforms/powernv/idle.c +++ b/arch/powerpc/platforms/powernv/idle.c @@ -79,7 +79,7 @@ static int pnv_save_sprs_for_deep_states(void) uint64_t msr_val = MSR_IDLE; uint64_t psscr_val = pnv_deepest_stop_psscr_val;
- for_each_possible_cpu(cpu) { + for_each_present_cpu(cpu) { uint64_t pir = get_hard_smp_processor_id(cpu); uint64_t hsprg0_val = (uint64_t)paca_ptrs[cpu];
@@ -814,7 +814,7 @@ static int __init pnv_init_idle_states(void) int cpu;
pr_info("powernv: idle: Saving PACA pointers of all CPUs in their thread sibling PACA\n"); - for_each_possible_cpu(cpu) { + for_each_present_cpu(cpu) { int base_cpu = cpu_first_thread_sibling(cpu); int idx = cpu_thread_in_core(cpu); int i;