+#include <linux/cgroup.h>
+#include <linux/err.h>
+#include <linux/percpu.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+
#include "sched.h"
unsigned int sysctl_sched_cfs_boost __read_mostly;
+#ifdef CONFIG_CGROUP_SCHEDTUNE
+
+/*
+ * EAS scheduler tunables for task groups.
+ */
+
+/* SchdTune tunables for a group of tasks */
+struct schedtune {
+ /* SchedTune CGroup subsystem */
+ struct cgroup_subsys_state css;
+
+ /* Boost group allocated ID */
+ int idx;
+
+ /* Boost value for tasks on that SchedTune CGroup */
+ int boost;
+
+};
+
+static inline struct schedtune *css_st(struct cgroup_subsys_state *css)
+{
+ return css ? container_of(css, struct schedtune, css) : NULL;
+}
+
+static inline struct schedtune *task_schedtune(struct task_struct *tsk)
+{
+ return css_st(task_css(tsk, schedtune_cgrp_id));
+}
+
+static inline struct schedtune *parent_st(struct schedtune *st)
+{
+ return css_st(st->css.parent);
+}
+
+/*
+ * SchedTune root control group
+ * The root control group is used to defined a system-wide boosting tuning,
+ * which is applied to all tasks in the system.
+ * Task specific boost tuning could be specified by creating and
+ * configuring a child control group under the root one.
+ * By default, system-wide boosting is disabled, i.e. no boosting is applied
+ * to tasks which are not into a child control group.
+ */
+static struct schedtune
+root_schedtune = {
+ .boost = 0,
+};
+
+/*
+ * Maximum number of boost groups to support
+ * When per-task boosting is used we still allow only limited number of
+ * boost groups for two main reasons:
+ * 1. on a real system we usually have only few classes of workloads which
+ * make sense to boost with different values (e.g. background vs foreground
+ * tasks, interactive vs low-priority tasks)
+ * 2. a limited number allows for a simpler and more memory/time efficient
+ * implementation especially for the computation of the per-CPU boost
+ * value
+ */
+#define BOOSTGROUPS_COUNT 4
+
+/* Array of configured boostgroups */
+static struct schedtune *allocated_group[BOOSTGROUPS_COUNT] = {
+ &root_schedtune,
+ NULL,
+};
+
+/* SchedTune boost groups
+ * Keep track of all the boost groups which impact on CPU, for example when a
+ * CPU has two RUNNABLE tasks belonging to two different boost groups and thus
+ * likely with different boost values.
+ * Since on each system we expect only a limited number of boost groups, here
+ * we use a simple array to keep track of the metrics required to compute the
+ * maximum per-CPU boosting value.
+ */
+struct boost_groups {
+ /* Maximum boost value for all RUNNABLE tasks on a CPU */
+ unsigned boost_max;
+ struct {
+ /* The boost for tasks on that boost group */
+ unsigned boost;
+ /* Count of RUNNABLE tasks on that boost group */
+ unsigned tasks;
+ } group[BOOSTGROUPS_COUNT];
+};
+
+/* Boost groups affecting each CPU in the system */
+DEFINE_PER_CPU(struct boost_groups, cpu_boost_groups);
+
+static u64
+boost_read(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+ struct schedtune *st = css_st(css);
+
+ return st->boost;
+}
+
+static int
+boost_write(struct cgroup_subsys_state *css, struct cftype *cft,
+ u64 boost)
+{
+ struct schedtune *st = css_st(css);
+
+ if (boost < 0 || boost > 100)
+ return -EINVAL;
+
+ st->boost = boost;
+ if (css == &root_schedtune.css)
+ sysctl_sched_cfs_boost = boost;
+
+ return 0;
+}
+
+static struct cftype files[] = {
+ {
+ .name = "boost",
+ .read_u64 = boost_read,
+ .write_u64 = boost_write,
+ },
+ { } /* terminate */
+};
+
+static int
+schedtune_boostgroup_init(struct schedtune *st)
+{
+ /* Keep track of allocated boost groups */
+ allocated_group[st->idx] = st;
+
+ return 0;
+}
+
+static int
+schedtune_init(void)
+{
+ struct boost_groups *bg;
+ int cpu;
+
+ /* Initialize the per CPU boost groups */
+ for_each_possible_cpu(cpu) {
+ bg = &per_cpu(cpu_boost_groups, cpu);
+ memset(bg, 0, sizeof(struct boost_groups));
+ }
+
+ pr_info(" schedtune configured to support %d boost groups\n",
+ BOOSTGROUPS_COUNT);
+ return 0;
+}
+
+static struct cgroup_subsys_state *
+schedtune_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct schedtune *st;
+ int idx;
+
+ if (!parent_css) {
+ schedtune_init();
+ return &root_schedtune.css;
+ }
+
+ /* Allow only single level hierachies */
+ if (parent_css != &root_schedtune.css) {
+ pr_err("Nested SchedTune boosting groups not allowed\n");
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* Allow only a limited number of boosting groups */
+ for (idx = 1; idx < BOOSTGROUPS_COUNT; ++idx)
+ if (!allocated_group[idx])
+ break;
+ if (idx == BOOSTGROUPS_COUNT) {
+ pr_err("Trying to create more than %d SchedTune boosting groups\n",
+ BOOSTGROUPS_COUNT);
+ return ERR_PTR(-ENOSPC);
+ }
+
+ st = kzalloc(sizeof(*st), GFP_KERNEL);
+ if (!st)
+ goto out;
+
+ /* Initialize per CPUs boost group support */
+ st->idx = idx;
+ if (schedtune_boostgroup_init(st))
+ goto release;
+
+ return &st->css;
+
+release:
+ kfree(st);
+out:
+ return ERR_PTR(-ENOMEM);
+}
+
+static void
+schedtune_boostgroup_release(struct schedtune *st)
+{
+ /* Keep track of allocated boost groups */
+ allocated_group[st->idx] = NULL;
+}
+
+static void
+schedtune_css_free(struct cgroup_subsys_state *css)
+{
+ struct schedtune *st = css_st(css);
+
+ schedtune_boostgroup_release(st);
+ kfree(st);
+}
+
+struct cgroup_subsys schedtune_cgrp_subsys = {
+ .css_alloc = schedtune_css_alloc,
+ .css_free = schedtune_css_free,
+ .legacy_cftypes = files,
+ .early_init = 1,
+};
+
+#endif /* CONFIG_CGROUP_SCHEDTUNE */
+
int
sysctl_sched_cfs_boost_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
projects / firefly-linux-kernel-4.4.55.git / commitdiff