This patch implements hard CPU rate caps per task as a proportion of a
single CPU's capacity expressed in parts per thousand.
Notes:
1. Simplified calculation of sinbin durations to eliminat need for 64 bit
divide.
Signed-off-by: Peter Williams <[EMAIL PROTECTED]>
include/linux/sched.h | 8 ++
kernel/Kconfig.caps | 14 +++-
kernel/sched.c | 160 +++++++++++++++++++++++++++++++++++++++++++++++---
3 files changed, 172 insertions(+), 10 deletions(-)
Index: MM-2.6.17-rc6-mm2/include/linux/sched.h
===================================================================
--- MM-2.6.17-rc6-mm2.orig/include/linux/sched.h 2006-06-14
11:08:40.000000000 +1000
+++ MM-2.6.17-rc6-mm2/include/linux/sched.h 2006-06-14 11:09:22.000000000
+1000
@@ -803,6 +803,10 @@ struct task_struct {
unsigned long long avg_cpu_per_cycle, avg_cycle_length;
unsigned int cpu_rate_cap;
unsigned int mutexes_held;
+#ifdef CONFIG_CPU_RATE_HARD_CAPS
+ unsigned int cpu_rate_hard_cap;
+ struct timer_list sinbin_timer;
+#endif
#endif
enum sleep_type sleep_type;
@@ -1020,6 +1024,10 @@ struct task_struct {
#ifdef CONFIG_CPU_RATE_CAPS
unsigned int get_cpu_rate_cap(const struct task_struct *);
int set_cpu_rate_cap(struct task_struct *, unsigned int);
+#ifdef CONFIG_CPU_RATE_HARD_CAPS
+unsigned int get_cpu_rate_hard_cap(const struct task_struct *);
+int set_cpu_rate_hard_cap(struct task_struct *, unsigned int);
+#endif
#endif
static inline pid_t process_group(struct task_struct *tsk)
Index: MM-2.6.17-rc6-mm2/kernel/Kconfig.caps
===================================================================
--- MM-2.6.17-rc6-mm2.orig/kernel/Kconfig.caps 2006-06-14 11:08:56.000000000
+1000
+++ MM-2.6.17-rc6-mm2/kernel/Kconfig.caps 2006-06-14 11:13:42.000000000
+1000
@@ -3,11 +3,21 @@
#
config CPU_RATE_CAPS
- bool "Support (soft) CPU rate caps"
+ bool "Support CPU rate caps"
default y
---help---
- Say y here if you wish to be able to put a (soft) upper limit on
+ Say y here if you wish to be able to put a soft upper limit on
the rate of CPU usage by individual tasks. A task which has been
allocated a soft CPU rate cap will be limited to that rate of CPU
usage unless there is spare CPU resources available after the needs
of uncapped tasks are met.
+
+config CPU_RATE_HARD_CAPS
+ bool "Support CPU rate hard caps"
+ depends on CPU_RATE_CAPS
+ default n
+ ---help---
+ Say y here if you wish to be able to put a hard upper limit on
+ the rate of CPU usage by individual tasks. A task which has been
+ allocated a hard CPU rate cap will be limited to that rate of CPU
+ usage regardless of whether there is spare CPU resources available.
Index: MM-2.6.17-rc6-mm2/kernel/sched.c
===================================================================
--- MM-2.6.17-rc6-mm2.orig/kernel/sched.c 2006-06-14 11:08:40.000000000
+1000
+++ MM-2.6.17-rc6-mm2/kernel/sched.c 2006-06-14 11:09:23.000000000 +1000
@@ -203,25 +203,39 @@ static inline unsigned int task_timeslic
#ifdef CONFIG_CPU_RATE_CAPS
#define CPU_CAP_ONE 1000
#define CAP_STATS_OFFSET 8
+#ifdef CONFIG_CPU_RATE_HARD_CAPS
+static void sinbin_release_fn(unsigned long arg);
+#define min_cpu_rate_cap(p) min((p)->cpu_rate_cap, (p)->cpu_rate_hard_cap)
+#else
+#define min_cpu_rate_cap(p) (p)->cpu_rate_cap
+#endif
#define task_has_cap(p) unlikely((p)->flags & PF_HAS_CAP)
/* this assumes that p is not a real time task */
#define task_is_background(p) unlikely((p)->cpu_rate_cap == 0)
#define task_being_capped(p) unlikely((p)->prio >= CAPPED_PRIO)
#define cap_load_weight(p) \
- (max((int)(((p)->cpu_rate_cap * SCHED_LOAD_SCALE) / CPU_CAP_ONE), 1))
+ (max((int)((min_cpu_rate_cap(p) * SCHED_LOAD_SCALE) / CPU_CAP_ONE), 1))
#define safe_to_enforce_cap(p) \
- (!((p)->mutexes_held || (p)->flags & (PF_FREEZE | PF_UIWAKE)))
+ (!((p)->mutexes_held || \
+ (p)->flags & (PF_FREEZE | PF_UIWAKE | PF_EXITING)))
+#define safe_to_sinbin(p) (safe_to_enforce_cap(p) && !signal_pending(p))
static void init_cpu_rate_caps(task_t *p)
{
p->cpu_rate_cap = CPU_CAP_ONE;
p->flags &= ~PF_HAS_CAP;
p->mutexes_held = 0;
+#ifdef CONFIG_CPU_RATE_HARD_CAPS
+ p->cpu_rate_hard_cap = CPU_CAP_ONE;
+ init_timer(&p->sinbin_timer);
+ p->sinbin_timer.function = sinbin_release_fn;
+ p->sinbin_timer.data = (unsigned long) p;
+#endif
}
static inline void set_cap_flag(task_t *p)
{
- if (p->cpu_rate_cap < CPU_CAP_ONE && !has_rt_policy(p))
+ if (min_cpu_rate_cap(p) < CPU_CAP_ONE && !has_rt_policy(p))
p->flags |= PF_HAS_CAP;
else
p->flags &= ~PF_HAS_CAP;
@@ -229,7 +243,7 @@ static inline void set_cap_flag(task_t *
static inline int task_exceeding_cap(const task_t *p)
{
- return (p->avg_cpu_per_cycle * CPU_CAP_ONE) > (p->avg_cycle_length *
p->cpu_rate_cap);
+ return (p->avg_cpu_per_cycle * CPU_CAP_ONE) > (p->avg_cycle_length *
min_cpu_rate_cap(p));
}
#ifdef CONFIG_SCHED_SMT
@@ -239,7 +253,7 @@ static inline int task_exceeding_cap(con
static unsigned int smt_timeslice(task_t *p)
{
if (task_being_capped(p))
- return (p->cpu_rate_cap * DEF_TIMESLICE) / CPU_CAP_ONE;
+ return (min_cpu_rate_cap(p) * DEF_TIMESLICE) / CPU_CAP_ONE;
return task_timeslice(p);
}
@@ -271,7 +285,7 @@ static int task_exceeding_cap_now(const
unsigned long long cpc = p->avg_cpu_per_cycle;
delta = (now > p->timestamp) ? (now - p->timestamp) : 0;
- rhs = (p->avg_cycle_length + delta) * p->cpu_rate_cap;
+ rhs = (p->avg_cycle_length + delta) * min_cpu_rate_cap(p);
if (oncpu)
cpc += delta;
@@ -283,6 +297,10 @@ static inline void init_cap_stats(task_t
p->avg_cpu_per_cycle = 0;
p->avg_cycle_length = 0;
p->mutexes_held = 0;
+#ifdef CONFIG_CPU_RATE_HARD_CAPS
+ init_timer(&p->sinbin_timer);
+ p->sinbin_timer.data = (unsigned long) p;
+#endif
}
static inline void inc_cap_stats_cycle(task_t *p, unsigned long long now)
@@ -315,6 +333,7 @@ static inline void decay_cap_stats(task_
#define task_being_capped(p) 0
#define cap_load_weight(p) ((int)SCHED_LOAD_SCALE)
#define safe_to_enforce_cap(p) 0
+#define safe_to_sinbin(p) 0
static inline void init_cpu_rate_caps(task_t *p)
{
@@ -1192,6 +1211,63 @@ static void deactivate_task(struct task_
p->array = NULL;
}
+#ifdef CONFIG_CPU_RATE_HARD_CAPS
+#define task_has_hard_cap(p) unlikely((p)->cpu_rate_hard_cap < CPU_CAP_ONE)
+
+/*
+ * Release a task from the sinbin
+ */
+static void sinbin_release_fn(unsigned long arg)
+{
+ unsigned long flags;
+ struct task_struct *p = (struct task_struct*)arg;
+ struct runqueue *rq = task_rq_lock(p, &flags);
+
+ p->prio = effective_prio(p);
+
+ __activate_task(p, rq);
+
+ task_rq_unlock(rq, &flags);
+}
+
+static unsigned long reqd_sinbin_ticks(const task_t *p)
+{
+ unsigned long long lhs = p->avg_cpu_per_cycle * CPU_CAP_ONE;
+ unsigned long long rhs = p->avg_cycle_length * p->cpu_rate_hard_cap;
+
+ if (lhs > rhs) {
+ lhs -= p->avg_cpu_per_cycle;
+ lhs >>= CAP_STATS_OFFSET;
+ /* have to do two divisions because there's no gaurantee
+ * that p->cpu_rate_hard_cap * (1000000000 / HZ) would
+ * not overflow a 32 bit unsigned integer
+ */
+ (void)do_div(lhs, p->cpu_rate_hard_cap);
+ (void)do_div(lhs, (1000000000 / HZ));
+
+ return lhs ? : 1;
+ }
+
+ return 0;
+}
+
+static void sinbin_task(task_t *p, unsigned long durn)
+{
+ if (durn == 0)
+ return;
+ deactivate_task(p, task_rq(p));
+ p->sinbin_timer.expires = jiffies + durn;
+ add_timer(&p->sinbin_timer);
+}
+#else
+#define task_has_hard_cap(p) 0
+#define reqd_sinbin_ticks(p) 0
+
+static inline void sinbin_task(task_t *p, unsigned long durn)
+{
+}
+#endif
+
/*
* resched_task - mark a task 'to be rescheduled now'.
*
@@ -3575,9 +3651,16 @@ need_resched_nonpreemptible:
}
}
- /* do this now so that stats are correct for SMT code */
- if (task_has_cap(prev))
+ if (task_has_cap(prev)) {
inc_cap_stats_both(prev, now);
+ if (task_has_hard_cap(prev) && !prev->state &&
+ !rt_task(prev) && safe_to_sinbin(prev)) {
+ unsigned long sinbin_ticks = reqd_sinbin_ticks(prev);
+
+ if (sinbin_ticks)
+ sinbin_task(prev, sinbin_ticks);
+ }
+ }
cpu = smp_processor_id();
if (unlikely(!rq->nr_running)) {
@@ -4598,6 +4681,67 @@ out:
}
EXPORT_SYMBOL(set_cpu_rate_cap);
+
+#ifdef CONFIG_CPU_RATE_HARD_CAPS
+unsigned int get_cpu_rate_hard_cap(const struct task_struct *p)
+{
+ return p->cpu_rate_hard_cap;
+}
+
+EXPORT_SYMBOL(get_cpu_rate_hard_cap);
+
+/*
+ * Require: 1 <= new_cap <= CPU_CAP_ONE
+ */
+int set_cpu_rate_hard_cap(struct task_struct *p, unsigned int new_cap)
+{
+ int is_allowed;
+ unsigned long flags;
+ struct runqueue *rq;
+ int delta;
+
+ if (new_cap > CPU_CAP_ONE || new_cap < 1)
+ return -EINVAL;
+ is_allowed = capable(CAP_SYS_NICE);
+ /*
+ * We have to be careful, if called from /proc code,
+ * the task might be in the middle of scheduling on another CPU.
+ */
+ rq = task_rq_lock(p, &flags);
+ delta = new_cap - p->cpu_rate_hard_cap;
+ if (!is_allowed) {
+ /*
+ * Ordinary users can set/change caps on their own tasks
+ * provided that the new setting is MORE constraining
+ */
+ if (((current->euid != p->uid) && (current->uid != p->uid)) ||
(delta > 0)) {
+ task_rq_unlock(rq, &flags);
+ return -EPERM;
+ }
+ }
+ /*
+ * The RT tasks don't have caps, but we still allow the caps to be
+ * set - but as expected it wont have any effect on scheduling until
+ * the task becomes SCHED_NORMAL/SCHED_BATCH:
+ */
+ p->cpu_rate_hard_cap = new_cap;
+
+ if (has_rt_policy(p))
+ goto out;
+
+ if (p->array)
+ dec_raw_weighted_load(rq, p);
+ set_load_weight(p);
+ if (p->array)
+ inc_raw_weighted_load(rq, p);
+out:
+ task_rq_unlock(rq, &flags);
+
+ return 0;
+}
+
+EXPORT_SYMBOL(set_cpu_rate_hard_cap);
+#endif
#endif
long sched_setaffinity(pid_t pid, cpumask_t new_mask)
--
Peter Williams [EMAIL PROTECTED]
"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
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