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Subject[PATCH V4 2/3] arm64: topology: Reorder init_amu_fie() a bit
Date
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.

Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
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
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