[PATCH 4.14 040/157] powerpc/powernv/cpuidle: Init all present cpus for deep states

From: Greg Kroah-Hartman
Date: Sun Jul 01 2018 - 13:50:58 EST

4.14-stable review patch. If anyone has any objections, please let me know.


From: Akshay Adiga <akshay.adiga@xxxxxxxxxxxxxxxxxx>

commit ac9816dcbab53c57bcf1d7b15370b08f1e284318 upstream.

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@xxxxxxxxxxxxxxx # v3.19+
Signed-off-by: Akshay Adiga <akshay.adiga@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/powerpc/platforms/powernv/idle.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -78,7 +78,7 @@ static int pnv_save_sprs_for_deep_states
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[cpu];

@@ -741,7 +741,7 @@ static int __init pnv_init_idle_states(v
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;