On Tuesday 15 Dec 2020 at 11:04:15 (+0530), Viresh Kumar wrote:
> This patch does a couple of optimizations in init_amu_fie(), like early
> exits from paths where we don't need to continue any further, avoid the
> enable/disable dance, moving the calls to
> topology_scale_freq_invariant() just when we need them, instead of at
> the top of the routine, and avoiding calling it for the third time.
>
> Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
> ---
> V3:
> - Skipped the enable/disable dance.
> - No need to call topology_scale_freq_invariant() multiple times.
>
> arch/arm64/kernel/topology.c | 27 ++++++++++++++-------------
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index ebadc73449f9..57267d694495 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -221,8 +221,8 @@ static DEFINE_STATIC_KEY_FALSE(amu_fie_key);
>
> static int __init init_amu_fie(void)
> {
> - bool invariance_status = topology_scale_freq_invariant();
> cpumask_var_t valid_cpus;
> + bool invariant;
> int ret = 0;
> int cpu;
>
> @@ -249,18 +249,19 @@ static int __init init_amu_fie(void)
> if (cpumask_equal(valid_cpus, cpu_present_mask))
> cpumask_copy(amu_fie_cpus, cpu_present_mask);
>
> - if (!cpumask_empty(amu_fie_cpus)) {
> - pr_info("CPUs[%*pbl]: counters will be used for FIE.",
> - cpumask_pr_args(amu_fie_cpus));
> - static_branch_enable(&amu_fie_key);
> - }
> + if (cpumask_empty(amu_fie_cpus))
> + goto free_valid_mask;
>
> - /*
> - * If the system is not fully invariant after AMU init, disable
> - * partial use of counters for frequency invariance.
> - */
> - if (!topology_scale_freq_invariant())
> - static_branch_disable(&amu_fie_key);
> + invariant = topology_scale_freq_invariant();
> +
> + /* We aren't fully invariant yet */
> + if (!invariant && !cpumask_equal(amu_fie_cpus, cpu_present_mask))
> + goto free_valid_mask;
> +
> + static_branch_enable(&amu_fie_key);
> +
> + pr_info("CPUs[%*pbl]: counters will be used for FIE.",
> + cpumask_pr_args(amu_fie_cpus));
>
> /*
> * Task scheduler behavior depends on frequency invariance support,
> @@ -268,7 +269,7 @@ static int __init init_amu_fie(void)
> * a result of counter initialisation and use, retrigger the build of
> * scheduling domains to ensure the information is propagated properly.
> */
> - if (invariance_status != topology_scale_freq_invariant())
> + if (!invariant)
> rebuild_sched_domains_energy();
>
> free_valid_mask:
> --
> 2.25.0.rc1.19.g042ed3e048af
>
Looks good!
Reviewed-by: Ionela Voinescu <ionela.voine...@arm.com>
