> On 05-Nov-2021, at 9:20 AM, Nicholas Piggin <npig...@gmail.com> wrote:
>
> This function builds the cores online map with on-stack cpumasks which
> can cause high stack usage with large NR_CPUS.
>
> It is not used in any performance sensitive paths, so instead just check
> for first thread sibling.
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
Tested-by: Sachin Sant <sach...@linux.vnet.ibm.com>
Thanks
- Sachin
> arch/powerpc/include/asm/cputhreads.h | 33 -----------------------
> arch/powerpc/platforms/powernv/idle.c | 10 +++----
> arch/powerpc/platforms/powernv/opal-imc.c | 6 ++---
> 3 files changed, 8 insertions(+), 41 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/cputhreads.h
> b/arch/powerpc/include/asm/cputhreads.h
> index b167186aaee4..f26c430f3982 100644
> --- a/arch/powerpc/include/asm/cputhreads.h
> +++ b/arch/powerpc/include/asm/cputhreads.h
> @@ -32,44 +32,11 @@ extern cpumask_t threads_core_mask;
> #define threads_core_mask (*get_cpu_mask(0))
> #endif
>
> -/* cpu_thread_mask_to_cores - Return a cpumask of one per cores
> - * hit by the argument
> - *
> - * @threads: a cpumask of online threads
> - *
> - * This function returns a cpumask which will have one online cpu's
> - * bit set for each core that has at least one thread set in the argument.
> - *
> - * This can typically be used for things like IPI for tlb invalidations
> - * since those need to be done only once per core/TLB
> - */
> -static inline cpumask_t cpu_thread_mask_to_cores(const struct cpumask
> *threads)
> -{
> - cpumask_t tmp, res;
> - int i, cpu;
> -
> - cpumask_clear(&res);
> - for (i = 0; i < NR_CPUS; i += threads_per_core) {
> - cpumask_shift_left(&tmp, &threads_core_mask, i);
> - if (cpumask_intersects(threads, &tmp)) {
> - cpu = cpumask_next_and(-1, &tmp, cpu_online_mask);
> - if (cpu < nr_cpu_ids)
> - cpumask_set_cpu(cpu, &res);
> - }
> - }
> - return res;
> -}
> -
> static inline int cpu_nr_cores(void)
> {
> return nr_cpu_ids >> threads_shift;
> }
>
> -static inline cpumask_t cpu_online_cores_map(void)
> -{
> - return cpu_thread_mask_to_cores(cpu_online_mask);
> -}
> -
> #ifdef CONFIG_SMP
> int cpu_core_index_of_thread(int cpu);
> int cpu_first_thread_of_core(int core);
> diff --git a/arch/powerpc/platforms/powernv/idle.c
> b/arch/powerpc/platforms/powernv/idle.c
> index e3ffdc8e8567..70da314fd2d7 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -146,9 +146,13 @@ EXPORT_SYMBOL_GPL(pnv_get_supported_cpuidle_states);
> static void pnv_fastsleep_workaround_apply(void *info)
>
> {
> + int cpu = smp_processor_id();
> int rc;
> int *err = info;
>
> + if (cpu_first_thread_sibling(cpu) != cpu)
> + return;
> +
> rc = opal_config_cpu_idle_state(OPAL_CONFIG_IDLE_FASTSLEEP,
> OPAL_CONFIG_IDLE_APPLY);
> if (rc)
> @@ -175,7 +179,6 @@ static ssize_t
> store_fastsleep_workaround_applyonce(struct device *dev,
> struct device_attribute *attr, const char *buf,
> size_t count)
> {
> - cpumask_t primary_thread_mask;
> int err;
> u8 val;
>
> @@ -200,10 +203,7 @@ static ssize_t
> store_fastsleep_workaround_applyonce(struct device *dev,
> power7_fastsleep_workaround_exit = false;
>
> cpus_read_lock();
> - primary_thread_mask = cpu_online_cores_map();
> - on_each_cpu_mask(&primary_thread_mask,
> - pnv_fastsleep_workaround_apply,
> - &err, 1);
> + on_each_cpu(pnv_fastsleep_workaround_apply, &err, 1);
> cpus_read_unlock();
> if (err) {
> pr_err("fastsleep_workaround_applyonce change failed while
> running pnv_fastsleep_workaround_apply");
> diff --git a/arch/powerpc/platforms/powernv/opal-imc.c
> b/arch/powerpc/platforms/powernv/opal-imc.c
> index 05d3832019b9..3fea5da6d1b3 100644
> --- a/arch/powerpc/platforms/powernv/opal-imc.c
> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
> @@ -200,13 +200,13 @@ static void disable_nest_pmu_counters(void)
>
> static void disable_core_pmu_counters(void)
> {
> - cpumask_t cores_map;
> int cpu, rc;
>
> cpus_read_lock();
> /* Disable the IMC Core functions */
> - cores_map = cpu_online_cores_map();
> - for_each_cpu(cpu, &cores_map) {
> + for_each_online_cpu(cpu) {
> + if (cpu_first_thread_sibling(cpu) != cpu)
> + continue;
> rc = opal_imc_counters_stop(OPAL_IMC_COUNTERS_CORE,
> get_hard_smp_processor_id(cpu));
> if (rc)
> --
> 2.23.0
>
