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walt/core_ctl: handle error conditions

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During test cases where multiple entities (thermal, core_ctl, hotplug)
attempting to pause or offline CPUs, error conditions caused core_ctl
to get stuck, unable to pause or resume CPUs.

Improve the core_ctl implementation such that an error to pause or
resume is carefully tracked, such that core_ctl will retry those
operations at a later time. Simplify paused_by_us to eliminate
redundant information.

Change-Id: Id156e6644da5264f5552daea7d3092916c44c434
Signed-off-by: Stephen Dickey <dickey@codeaurora.org>
This commit is contained in:
Stephen Dickey 2021-03-12 13:20:57 -08:00 committed by Rishabh Bhatnagar
parent 5475717e77
commit 0485ca1db5
1 changed files with 76 additions and 19 deletions
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95
kernel/sched/walt/core_ctl.c
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@ -19,6 +19,9 @@
#include "walt.h"
#include "trace.h"
/* mask of CPUs on which there is an outstanding pause claim */
static cpumask_t cpus_paused_by_us = { CPU_BITS_NONE };
struct cluster_data {
bool inited;
unsigned int min_cpus;
@ -28,7 +31,6 @@ struct cluster_data {
unsigned int busy_down_thres[MAX_CPUS_PER_CLUSTER];
unsigned int active_cpus;
unsigned int num_cpus;
unsigned int nr_paused_cpus;
unsigned int nr_not_preferred_cpus;
cpumask_t cpu_mask;
unsigned int need_cpus;
@ -53,7 +55,6 @@ struct cpu_data {
bool not_preferred;
struct cluster_data *cluster;
struct list_head sib;
bool paused_by_us;
bool disabled;
};
@ -289,6 +290,14 @@ static ssize_t show_active_cpus(const struct cluster_data *state, char *buf)
return scnprintf(buf, PAGE_SIZE, "%u\n", state->active_cpus);
}
static unsigned int nr_paused_cpus(const struct cluster_data *cluster)
{
cpumask_t cluster_paused_cpus;
cpumask_and(&cluster_paused_cpus, &cluster->cpu_mask, &cpus_paused_by_us);
return cpumask_weight(&cluster_paused_cpus);
}
static ssize_t show_global_state(const struct cluster_data *state, char *buf)
{
struct cpu_data *c;
@ -331,7 +340,7 @@ static ssize_t show_global_state(const struct cluster_data *state, char *buf)
"\tNeed CPUs: %u\n", cluster->need_cpus);
count += scnprintf(buf + count, PAGE_SIZE - count,
"\tNr paused CPUs: %u\n",
cluster->nr_paused_cpus);
nr_paused_cpus(cluster));
count += scnprintf(buf + count, PAGE_SIZE - count,
"\tBoost: %u\n", (unsigned int) cluster->boost);
}
@ -607,7 +616,7 @@ static int prev_cluster_nr_need_assist(int index)
* Next cluster should not assist, while there are paused cpus
* in this cluster.
*/
if (prev_cluster->nr_paused_cpus)
if (nr_paused_cpus(prev_cluster))
return 0;
for_each_cpu(cpu, &prev_cluster->cpu_mask)
@ -768,7 +777,7 @@ static bool adjustment_possible(const struct cluster_data *cluster,
unsigned int need)
{
return (need < cluster->active_cpus || (need > cluster->active_cpus &&
cluster->nr_paused_cpus));
nr_paused_cpus(cluster)));
}
static bool need_all_cpus(const struct cluster_data *cluster)
@ -1029,8 +1038,6 @@ static void try_to_pause(struct cluster_data *cluster, unsigned int need,
pr_debug("Trying to pause CPU%u\n", c->cpu);
cpumask_set_cpu(c->cpu, pause_cpus);
nr_pending++;
c->paused_by_us = true;
cluster->nr_paused_cpus++;
move_cpu_lru(c);
}
@ -1059,8 +1066,6 @@ static void try_to_pause(struct cluster_data *cluster, unsigned int need,
cpumask_set_cpu(c->cpu, pause_cpus);
nr_pending++;
c->paused_by_us = true;
cluster->nr_paused_cpus++;
move_cpu_lru(c);
}
@ -1089,7 +1094,7 @@ static int __try_to_resume(struct cluster_data *cluster, unsigned int need,
if (!num_cpus--)
break;
if (!c->paused_by_us)
if (!cpumask_test_cpu(c->cpu, &cpus_paused_by_us))
continue;
if ((cpu_online(c->cpu) && cpu_active(c->cpu)) ||
(!force && c->not_preferred))
@ -1101,8 +1106,6 @@ static int __try_to_resume(struct cluster_data *cluster, unsigned int need,
cpumask_set_cpu(c->cpu, unpause_cpus);
nr_pending++;
c->paused_by_us = false;
cluster->nr_paused_cpus--;
move_cpu_lru(c);
}
@ -1122,8 +1125,7 @@ static void try_to_resume(struct cluster_data *cluster, unsigned int need,
* won't be reflected yet. So use the nr_pending to adjust active
* count.
*/
nr_pending = __try_to_resume(cluster, need, force_use_non_preferred,
unpause_cpus);
nr_pending = __try_to_resume(cluster, need, force_use_non_preferred, unpause_cpus);
if (cluster->active_cpus + nr_pending == need)
return;
@ -1132,6 +1134,64 @@ static void try_to_resume(struct cluster_data *cluster, unsigned int need,
__try_to_resume(cluster, need, force_use_non_preferred, unpause_cpus);
}
/*
* core_ctl_pause_cpus: pause a set of CPUs as requested by core_ctl, handling errors.
*
* In order to handle errors properly, and properly track success, the cpus being
* passed to walt_pause_cpus needs to be saved off. It needs to be saved because
* walt_pause_cpus will modify the value (through pause_cpus()). Pause_cpus modifies
* the value because it updates the variable to eliminate CPUs that are already paused.
* THIS code, however, must be very careful to track what cpus were requested, rather
* than what cpus actually were paused in this action. Otherwise, the ref-counts in
* walt_pause.c will get out of sync with this code.
*/
static void core_ctl_pause_cpus(struct cpumask *cpus_to_pause)
{
cpumask_t saved_cpus;
/* be careful to only pause CPUs not paused before to ensure ref-count sync */
cpumask_andnot(cpus_to_pause, cpus_to_pause, &cpus_paused_by_us);
cpumask_copy(&saved_cpus, cpus_to_pause);
if (cpumask_any(cpus_to_pause) < nr_cpu_ids) {
if (walt_pause_cpus(cpus_to_pause) < 0)
pr_warn("core_ctl pause operation failed cpus=%*pbl paused_by_us=%*pbl\n",
cpumask_pr_args(cpus_to_pause),
cpumask_pr_args(&cpus_paused_by_us));
else
cpumask_or(&cpus_paused_by_us, &cpus_paused_by_us, &saved_cpus);
}
}
/*
* core_ctl_resume_cpus: resume a set of CPUs as requested by core_ctl, handling errors.
*
* In order to handle errors properly, and properly track success, the cpus being
* passed to walt_resume_cpus needs to be saved off. It needs to be saved because
* walt_resume_cpus will modify the value (through resume_cpus()). Resume_cpus modifies
* the value because it updates the variable to eliminate CPUs that are already resumed.
* THIS code, however, must be very careful to track what cpus were requested, rather
* than what cpus actually were resumed in this action. Otherwise, the ref-counts in
* walt_pause.c will get out of sync with this code.
*/
static void core_ctl_resume_cpus(struct cpumask *cpus_to_unpause)
{
cpumask_t saved_cpus;
/* be careful to only unpause CPUs paused before to ensure ref-count sync */
cpumask_and(cpus_to_unpause, cpus_to_unpause, &cpus_paused_by_us);
cpumask_copy(&saved_cpus, cpus_to_unpause);
if (cpumask_any(cpus_to_unpause) < nr_cpu_ids) {
if (walt_resume_cpus(cpus_to_unpause) < 0)
pr_warn("core_ctl resume operation failed cpus=%*pbl paused_by_us=%*pbl\n",
cpumask_pr_args(cpus_to_unpause),
cpumask_pr_args(&cpus_paused_by_us));
else
cpumask_andnot(&cpus_paused_by_us, &cpus_paused_by_us, &saved_cpus);
}
}
static void __ref do_core_ctl(void)
{
struct cluster_data *cluster;
@ -1157,11 +1217,8 @@ static void __ref do_core_ctl(void)
}
}
if (cpumask_any(&cpus_to_pause) < nr_cpu_ids)
walt_pause_cpus(&cpus_to_pause);
if (cpumask_any(&cpus_to_unpause) < nr_cpu_ids)
walt_resume_cpus(&cpus_to_unpause);
core_ctl_pause_cpus(&cpus_to_pause);
core_ctl_resume_cpus(&cpus_to_unpause);
}
static int __ref try_core_ctl(void *data)