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Subject[patch 03/15] sched: accumulate per-cfs_rq cpu usage
Introduce account_cfs_rq_quota() to account bandwidth usage on the cfs_rq
level versus task_groups for which bandwidth has been assigned. This is
tracked by whether the local cfs_rq->quota_assigned is finite or infinite
(RUNTIME_INF).

For cfs_rq's that belong to a bandwidth constrained task_group we introduce
tg_request_cfs_quota() which attempts to allocate quota from the global pool
for use locally. Updates involving the global pool are currently protected
under cfs_bandwidth->lock, local pools are protected by rq->lock.

This patch only attempts to assign and track quota, no action is taken in the
case that cfs_rq->quota_used exceeds cfs_rq->quota_assigned.

Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Nikhil Rao <ncrao@google.com>
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
include/linux/sched.h | 4 +++
kernel/sched_fair.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/sysctl.c | 8 +++++++
3 files changed, 69 insertions(+)
Index: tip/kernel/sched_fair.c
===================================================================
--- tip.orig/kernel/sched_fair.c
+++ tip/kernel/sched_fair.c
@@ -96,6 +96,15 @@ unsigned int __read_mostly sysctl_sched_
unsigned int sysctl_sched_cfs_bandwidth_consistent = 1;
#endif

+#ifdef CONFIG_CFS_BANDWIDTH
+/*
+ * amount of quota to allocate from global tg to local cfs_rq pool on each
+ * refresh
+ * default: 5ms, units: microseconds
+ */
+unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
+#endif
+
static const struct sched_class fair_sched_class;

/**************************************************************
@@ -312,6 +321,8 @@ find_matching_se(struct sched_entity **s

#endif /* CONFIG_FAIR_GROUP_SCHED */

+static void account_cfs_rq_quota(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec);

/**************************************************************
* Scheduling class tree data structure manipulation methods:
@@ -605,6 +616,8 @@ static void update_curr(struct cfs_rq *c
cpuacct_charge(curtask, delta_exec);
account_group_exec_runtime(curtask, delta_exec);
}
+
+ account_cfs_rq_quota(cfs_rq, delta_exec);
}

static inline void
@@ -1276,6 +1289,47 @@ static inline u64 default_cfs_period(voi
return 500000000ULL;
}

+static inline u64 sched_cfs_bandwidth_slice(void)
+{
+ return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
+}
+
+static void request_cfs_rq_quota(struct cfs_rq *cfs_rq)
+{
+ struct task_group *tg = cfs_rq->tg;
+ struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
+ u64 amount = 0, min_amount;
+
+ min_amount = sched_cfs_bandwidth_slice() + (-cfs_rq->quota_remaining);
+
+ if (cfs_b->runtime > 0 || cfs_b->quota == RUNTIME_INF) {
+ raw_spin_lock(&cfs_b->lock);
+ if (cfs_b->quota != RUNTIME_INF) {
+ amount = min(cfs_b->runtime, min_amount);
+ cfs_b->runtime -= amount;
+ } else {
+ amount = min_amount;
+ }
+ raw_spin_unlock(&cfs_b->lock);
+ }
+
+ cfs_rq->quota_remaining += amount;
+}
+
+static void account_cfs_rq_quota(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec)
+{
+ if (!cfs_rq->quota_enabled)
+ return;
+
+ cfs_rq->quota_remaining -= delta_exec;
+
+ if (cfs_rq->quota_remaining > 0)
+ return;
+
+ request_cfs_rq_quota(cfs_rq);
+}
+
static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
{
return 1;
@@ -1285,6 +1339,9 @@ static inline u64 default_cfs_period(voi
{
return 0;
}
+
+static void account_cfs_rq_quota(struct cfs_rq *cfs_rq,
+ unsigned long delta_exec) {}
#endif


Index: tip/kernel/sysctl.c
===================================================================
--- tip.orig/kernel/sysctl.c
+++ tip/kernel/sysctl.c
@@ -371,6 +371,14 @@ static struct ctl_table kern_table[] = {
.extra1 = &zero,
.extra2 = &one,
},
+ {
+ .procname = "sched_cfs_bandwidth_slice_us",
+ .data = &sysctl_sched_cfs_bandwidth_slice,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
+ },
#endif
#ifdef CONFIG_SCHED_AUTOGROUP
{
Index: tip/include/linux/sched.h
===================================================================
--- tip.orig/include/linux/sched.h
+++ tip/include/linux/sched.h
@@ -1951,6 +1951,10 @@ int sched_cfs_consistent_handler(struct
loff_t *ppos);
#endif

+#ifdef CONFIG_CFS_BANDWIDTH
+extern unsigned int sysctl_sched_cfs_bandwidth_slice;
+#endif
+
#ifdef CONFIG_SCHED_AUTOGROUP
extern unsigned int sysctl_sched_autogroup_enabled;




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