From 0e93f1c780e8fd315f1262467b7d35eb6f766d2f Mon Sep 17 00:00:00 2001 From: Srikar Dronamraju Date: Thu, 14 Dec 2023 23:37:14 +0530 Subject: powerpc/smp: Avoid asym packing within thread_group of a core PowerVM Hypervisor will schedule at a core granularity. However each core can have more than one thread_groups. For better utilization in case of a shared processor, its preferable for the scheduler to pack to the lowest core. However there is no benefit of moving a thread between two thread groups of the same core. Signed-off-by: Srikar Dronamraju Signed-off-by: Michael Ellerman Link: https://msgid.link/20231214180720.310852-5-srikar@linux.vnet.ibm.com --- arch/powerpc/kernel/smp.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/powerpc/kernel') diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index aea149627209..9d8bb9a084bd 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -1763,6 +1763,19 @@ void __init smp_cpus_done(unsigned int max_cpus) set_sched_topology(powerpc_topology); } +/* + * For asym packing, by default lower numbered CPU has higher priority. + * On shared processors, pack to lower numbered core. However avoid moving + * between thread_groups within the same core. + */ +int arch_asym_cpu_priority(int cpu) +{ + if (static_branch_unlikely(&splpar_asym_pack)) + return -cpu / threads_per_core; + + return -cpu; +} + #ifdef CONFIG_HOTPLUG_CPU int __cpu_disable(void) { -- cgit v1.2.3