4.17-stable review patch. If anyone has any objections, please let me know.
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From: Akshay Adiga akshay.adiga@linux.vnet.ibm.com
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@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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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 @@ -79,7 +79,7 @@ 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_ptrs[cpu];
@@ -814,7 +814,7 @@ 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;