Merge git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched
* git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched: sched: cleanup, sched_granularity -> sched_min_granularity sched: adaptive scheduler granularity sched: fix CONFIG_SCHED_DEBUG dependency of lockdep sysctls
This commit is contained in:
Linus Torvalds
commit
a3ce8ea66a
4 changed files with 99 additions and 30 deletions
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@ -1399,7 +1399,8 @@ static inline void idle_task_exit(void) {}
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extern void sched_idle_next(void);
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extern unsigned int sysctl_sched_granularity;
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extern unsigned int sysctl_sched_latency;
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extern unsigned int sysctl_sched_min_granularity;
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extern unsigned int sysctl_sched_wakeup_granularity;
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extern unsigned int sysctl_sched_batch_wakeup_granularity;
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extern unsigned int sysctl_sched_stat_granularity;
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@ -4911,14 +4911,18 @@ cpumask_t nohz_cpu_mask = CPU_MASK_NONE;
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static inline void sched_init_granularity(void)
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{
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unsigned int factor = 1 + ilog2(num_online_cpus());
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const unsigned long gran_limit = 100000000;
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const unsigned long limit = 100000000;
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sysctl_sched_granularity *= factor;
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if (sysctl_sched_granularity > gran_limit)
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sysctl_sched_granularity = gran_limit;
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sysctl_sched_min_granularity *= factor;
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if (sysctl_sched_min_granularity > limit)
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sysctl_sched_min_granularity = limit;
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sysctl_sched_runtime_limit = sysctl_sched_granularity * 5;
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sysctl_sched_wakeup_granularity = sysctl_sched_granularity / 2;
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sysctl_sched_latency *= factor;
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if (sysctl_sched_latency > limit)
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sysctl_sched_latency = limit;
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sysctl_sched_runtime_limit = sysctl_sched_latency * 5;
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sysctl_sched_wakeup_granularity = sysctl_sched_latency / 2;
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}
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#ifdef CONFIG_SMP
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@ -15,23 +15,32 @@
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*
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* Scaled math optimizations by Thomas Gleixner
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* Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
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*
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* Adaptive scheduling granularity, math enhancements by Peter Zijlstra
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* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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*/
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/*
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* Preemption granularity:
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* (default: 10 msec, units: nanoseconds)
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* Targeted preemption latency for CPU-bound tasks:
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* (default: 20ms, units: nanoseconds)
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*
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* NOTE: this granularity value is not the same as the concept of
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* 'timeslice length' - timeslices in CFS will typically be somewhat
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* larger than this value. (to see the precise effective timeslice
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* length of your workload, run vmstat and monitor the context-switches
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* field)
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* NOTE: this latency value is not the same as the concept of
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* 'timeslice length' - timeslices in CFS are of variable length.
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* (to see the precise effective timeslice length of your workload,
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* run vmstat and monitor the context-switches field)
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*
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* On SMP systems the value of this is multiplied by the log2 of the
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* number of CPUs. (i.e. factor 2x on 2-way systems, 3x on 4-way
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* systems, 4x on 8-way systems, 5x on 16-way systems, etc.)
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* Targeted preemption latency for CPU-bound tasks:
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*/
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unsigned int sysctl_sched_granularity __read_mostly = 10000000UL;
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unsigned int sysctl_sched_latency __read_mostly = 20000000ULL;
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/*
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* Minimal preemption granularity for CPU-bound tasks:
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* (default: 2 msec, units: nanoseconds)
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*/
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unsigned int sysctl_sched_min_granularity __read_mostly = 2000000ULL;
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/*
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* SCHED_BATCH wake-up granularity.
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@ -212,6 +221,49 @@ static struct sched_entity *__pick_next_entity(struct cfs_rq *cfs_rq)
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* Scheduling class statistics methods:
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*/
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/*
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* Calculate the preemption granularity needed to schedule every
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* runnable task once per sysctl_sched_latency amount of time.
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* (down to a sensible low limit on granularity)
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*
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* For example, if there are 2 tasks running and latency is 10 msecs,
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* we switch tasks every 5 msecs. If we have 3 tasks running, we have
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* to switch tasks every 3.33 msecs to get a 10 msecs observed latency
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* for each task. We do finer and finer scheduling up to until we
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* reach the minimum granularity value.
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*
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* To achieve this we use the following dynamic-granularity rule:
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*
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* gran = lat/nr - lat/nr/nr
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*
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* This comes out of the following equations:
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*
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* kA1 + gran = kB1
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* kB2 + gran = kA2
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* kA2 = kA1
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* kB2 = kB1 - d + d/nr
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* lat = d * nr
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*
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* Where 'k' is key, 'A' is task A (waiting), 'B' is task B (running),
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* '1' is start of time, '2' is end of time, 'd' is delay between
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* 1 and 2 (during which task B was running), 'nr' is number of tasks
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* running, 'lat' is the the period of each task. ('lat' is the
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* sched_latency that we aim for.)
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*/
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static long
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sched_granularity(struct cfs_rq *cfs_rq)
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{
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unsigned int gran = sysctl_sched_latency;
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unsigned int nr = cfs_rq->nr_running;
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if (nr > 1) {
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gran = gran/nr - gran/nr/nr;
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gran = max(gran, sysctl_sched_min_granularity);
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}
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return gran;
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}
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/*
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* We rescale the rescheduling granularity of tasks according to their
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* nice level, but only linearly, not exponentially:
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@ -302,7 +354,7 @@ __update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr)
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delta_fair = calc_delta_fair(delta_exec, lw);
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delta_mine = calc_delta_mine(delta_exec, curr->load.weight, lw);
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if (cfs_rq->sleeper_bonus > sysctl_sched_granularity) {
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if (cfs_rq->sleeper_bonus > sysctl_sched_latency) {
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delta = min((u64)delta_mine, cfs_rq->sleeper_bonus);
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delta = min(delta, (unsigned long)(
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(long)sysctl_sched_runtime_limit - curr->wait_runtime));
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@ -689,7 +741,8 @@ static void entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
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if (next == curr)
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return;
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__check_preempt_curr_fair(cfs_rq, next, curr, sysctl_sched_granularity);
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__check_preempt_curr_fair(cfs_rq, next, curr,
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sched_granularity(cfs_rq));
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}
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/**************************************************
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@ -1034,7 +1087,7 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
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* it will preempt the parent:
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*/
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p->se.fair_key = current->se.fair_key -
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niced_granularity(&rq->curr->se, sysctl_sched_granularity) - 1;
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niced_granularity(&rq->curr->se, sched_granularity(cfs_rq)) - 1;
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/*
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* The first wait is dominated by the child-runs-first logic,
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* so do not credit it with that waiting time yet:
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@ -1047,7 +1100,7 @@ static void task_new_fair(struct rq *rq, struct task_struct *p)
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* -granularity/2, so initialize the task with that:
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*/
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if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)
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p->se.wait_runtime = -((long)sysctl_sched_granularity / 2);
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p->se.wait_runtime = -(sched_granularity(cfs_rq) / 2);
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__enqueue_entity(cfs_rq, se);
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}
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@ -222,8 +222,19 @@ static ctl_table kern_table[] = {
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#ifdef CONFIG_SCHED_DEBUG
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{
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.ctl_name = CTL_UNNUMBERED,
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.procname = "sched_granularity_ns",
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.data = &sysctl_sched_granularity,
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.procname = "sched_min_granularity_ns",
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.data = &sysctl_sched_min_granularity,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.strategy = &sysctl_intvec,
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.extra1 = &min_sched_granularity_ns,
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.extra2 = &max_sched_granularity_ns,
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},
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{
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.ctl_name = CTL_UNNUMBERED,
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.procname = "sched_latency_ns",
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.data = &sysctl_sched_latency,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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@ -283,6 +294,15 @@ static ctl_table kern_table[] = {
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.mode = 0644,
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.proc_handler = &proc_dointvec,
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},
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{
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.ctl_name = CTL_UNNUMBERED,
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.procname = "sched_features",
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.data = &sysctl_sched_features,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = &proc_dointvec,
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},
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#endif
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#ifdef CONFIG_PROVE_LOCKING
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{
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.ctl_name = CTL_UNNUMBERED,
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@ -302,15 +322,6 @@ static ctl_table kern_table[] = {
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.mode = 0644,
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.proc_handler = &proc_dointvec,
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},
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#endif
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{
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.ctl_name = CTL_UNNUMBERED,
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.procname = "sched_features",
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.data = &sysctl_sched_features,
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.maxlen = sizeof(unsigned int),
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.mode = 0644,
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.proc_handler = &proc_dointvec,
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},
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#endif
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{
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.ctl_name = KERN_PANIC,
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