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Revert "sched/fair: Detect capacity inversion"

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This reverts commit 30f04dd56d.

It breaks the Android kernel abi, so revert it.  If it needs to come
back later, it can do so in an abi-safe way.

Bug: 161946584
Cc: Qais Yousef <qyousef@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I576fa3894406ad6db3d4eafe5c08572d20c71902
This commit is contained in:
Greg Kroah-Hartman
2023-06-20 11:19:02 +00:00
parent ce3ecd63bf
commit 571879dd5f
2 changed files with 3 additions and 79 deletions
Download Patch File Download Diff File Expand all files Collapse all files

63
kernel/sched/fair.c
View File

@@ -8513,74 +8513,17 @@ static unsigned long scale_rt_capacity(int cpu)
static void update_cpu_capacity(struct sched_domain *sd, int cpu)
{
unsigned long capacity_orig = arch_scale_cpu_capacity(cpu);
unsigned long capacity = scale_rt_capacity(cpu);
struct sched_group *sdg = sd->groups;
struct rq *rq = cpu_rq(cpu);
rq->cpu_capacity_orig = capacity_orig;
cpu_rq(cpu)->cpu_capacity_orig = arch_scale_cpu_capacity(cpu);
if (!capacity)
capacity = 1;
trace_android_rvh_update_cpu_capacity(cpu, &capacity);
rq->cpu_capacity = capacity;
/*
* Detect if the performance domain is in capacity inversion state.
*
* Capacity inversion happens when another perf domain with equal or
* lower capacity_orig_of() ends up having higher capacity than this
* domain after subtracting thermal pressure.
*
* We only take into account thermal pressure in this detection as it's
* the only metric that actually results in *real* reduction of
* capacity due to performance points (OPPs) being dropped/become
* unreachable due to thermal throttling.
*
* We assume:
* * That all cpus in a perf domain have the same capacity_orig
* (same uArch).
* * Thermal pressure will impact all cpus in this perf domain
* equally.
*/
if (static_branch_unlikely(&sched_asym_cpucapacity)) {
unsigned long inv_cap = capacity_orig - thermal_load_avg(rq);
struct perf_domain *pd = rcu_dereference(rq->rd->pd);
rq->cpu_capacity_inverted = 0;
for (; pd; pd = pd->next) {
struct cpumask *pd_span = perf_domain_span(pd);
unsigned long pd_cap_orig, pd_cap;
cpu = cpumask_any(pd_span);
pd_cap_orig = arch_scale_cpu_capacity(cpu);
if (capacity_orig < pd_cap_orig)
continue;
/*
* handle the case of multiple perf domains have the
* same capacity_orig but one of them is under higher
* thermal pressure. We record it as capacity
* inversion.
*/
if (capacity_orig == pd_cap_orig) {
pd_cap = pd_cap_orig - thermal_load_avg(cpu_rq(cpu));
if (pd_cap > inv_cap) {
rq->cpu_capacity_inverted = inv_cap;
break;
}
} else if (pd_cap_orig > inv_cap) {
rq->cpu_capacity_inverted = inv_cap;
break;
}
}
}
trace_sched_cpu_capacity_tp(rq);
cpu_rq(cpu)->cpu_capacity = capacity;
trace_sched_cpu_capacity_tp(cpu_rq(cpu));
sdg->sgc->capacity = capacity;
sdg->sgc->min_capacity = capacity;

19
kernel/sched/sched.h
View File

@@ -993,7 +993,6 @@ struct rq {
unsigned long cpu_capacity;
unsigned long cpu_capacity_orig;
unsigned long cpu_capacity_inverted;
struct callback_head *balance_callback;
@@ -2625,24 +2624,6 @@ static inline unsigned long capacity_orig_of(int cpu)
{
return cpu_rq(cpu)->cpu_capacity_orig;
}
/*
* Returns inverted capacity if the CPU is in capacity inversion state.
* 0 otherwise.
*
* Capacity inversion detection only considers thermal impact where actual
* performance points (OPPs) gets dropped.
*
* Capacity inversion state happens when another performance domain that has
* equal or lower capacity_orig_of() becomes effectively larger than the perf
* domain this CPU belongs to due to thermal pressure throttling it hard.
*
* See comment in update_cpu_capacity().
*/
static inline unsigned long cpu_in_capacity_inversion(int cpu)
{
return cpu_rq(cpu)->cpu_capacity_inverted;
}
#endif
/**