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charset="utf-8" Use sysfs to provide hint. Depending on the system configuration one needs to decide the number. vp - virtual processor or vCPU.=20 For example, when 40 > vp_manual_hint means scheduler is supposed to use only 0-39 vCPUs. By default, vp_manual_hint is set to all possible CPUs=20 and it has be at least 1.=20 This is for illustration only. Not meant to be merged. One can modify as per their arch. =20 Signed-off-by: Shrikanth Hegde --- arch/powerpc/kernel/smp.c | 45 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 5ac7084eebc0..37eb6aa71613 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -64,6 +64,7 @@ #include =20 #include +#include =20 #ifdef DEBUG #include @@ -82,6 +83,7 @@ bool has_big_cores __ro_after_init; bool coregroup_enabled __ro_after_init; bool thread_group_shares_l2 __ro_after_init; bool thread_group_shares_l3 __ro_after_init; +static int vp_manual_hint =3D NR_CPUS; =20 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map); DEFINE_PER_CPU(cpumask_var_t, cpu_smallcore_map); @@ -1727,6 +1729,7 @@ static void __init build_sched_topology(void) BUG_ON(i >=3D ARRAY_SIZE(powerpc_topology) - 1); =20 set_sched_topology(powerpc_topology); + vp_manual_hint =3D num_present_cpus(); } =20 void __init smp_cpus_done(unsigned int max_cpus) @@ -1807,4 +1810,46 @@ void __noreturn arch_cpu_idle_dead(void) start_secondary_resume(); } =20 +/* + * sysfs hint to mark CPUs as parked. This will help in restricting + * the workload to specified number of CPUs. + * For example 40 > vp_manual_hint means, workload will run on + * 0-39 CPUs. + */ + +static int pv_vp_manual_hint_set(void *data, u64 val) +{ + int cpu; + + if (val =3D=3D 0 || vp_manual_hint > num_present_cpus()) + vp_manual_hint =3D num_present_cpus(); + + if (val !=3D vp_manual_hint) + vp_manual_hint =3D val; + + for_each_present_cpu(cpu) { + if (cpu >=3D vp_manual_hint) + set_cpu_parked(cpu, true); + else + set_cpu_parked(cpu, false); + } + return 0; +} + +static int pv_vp_manual_hint_get(void *data, u64 *val) +{ + *val =3D vp_manual_hint; + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(fops_pv_vp_manual_hint, pv_vp_manual_hint_get, pv_= vp_manual_hint_set, "%llu\n"); + +static __init int paravirt_debugfs_init(void) +{ + if (is_shared_processor()) + debugfs_create_file("vp_manual_hint", 0600, arch_debugfs_dir, NULL, &fop= s_pv_vp_manual_hint); + return 0; +} + +device_initcall(paravirt_debugfs_init) #endif --=20 2.39.3