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authorIngo Molnar <mingo@kernel.org>2012-12-08 15:31:07 +0100
committerIngo Molnar <mingo@kernel.org>2012-12-08 15:31:07 +0100
commite783377e93d4043a11013ce6e9173db34998e653 (patch)
tree47a56d363512337d78aa1cef0b620cbc7b53092f /kernel
parent222e82bef4bd520a31d48c31ab24e49dd46daa46 (diff)
parentfa09205783d11cc05122ad6e4ce06074624b2c0c (diff)
Merge tag 'cputime-adjustment-cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into sched/core
Pull cputime cleanups from Frederic Weisbecker: * Improve naming and code location * Consolidate adjustment code * Comment the adjustement code Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/exit.c4
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/posix-cpu-timers.c24
-rw-r--r--kernel/sched/auto_group.c64
-rw-r--r--kernel/sched/auto_group.h4
-rw-r--r--kernel/sched/cputime.c98
-rw-r--r--kernel/sched/fair.c2
-rw-r--r--kernel/sched/features.h5
-rw-r--r--kernel/sys.c6
-rw-r--r--kernel/sysctl.c6
10 files changed, 96 insertions, 119 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 346616c0092..618f7ee5600 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1186,11 +1186,11 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
* as other threads in the parent group can be right
* here reaping other children at the same time.
*
- * We use thread_group_times() to get times for the thread
+ * We use thread_group_cputime_adjusted() to get times for the thread
* group, which consolidates times for all threads in the
* group including the group leader.
*/
- thread_group_times(p, &tgutime, &tgstime);
+ thread_group_cputime_adjusted(p, &tgutime, &tgstime);
spin_lock_irq(&p->real_parent->sighand->siglock);
psig = p->real_parent->signal;
sig = p->signal;
diff --git a/kernel/fork.c b/kernel/fork.c
index 8b20ab7d3aa..0e7cdb90476 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1222,7 +1222,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
p->utime = p->stime = p->gtime = 0;
p->utimescaled = p->stimescaled = 0;
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
- p->prev_utime = p->prev_stime = 0;
+ p->prev_cputime.utime = p->prev_cputime.stime = 0;
#endif
#if defined(SPLIT_RSS_COUNTING)
memset(&p->rss_stat, 0, sizeof(p->rss_stat));
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 125cb67daa2..d73840271dc 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -217,30 +217,6 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p,
return 0;
}
-void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
-{
- struct signal_struct *sig = tsk->signal;
- struct task_struct *t;
-
- times->utime = sig->utime;
- times->stime = sig->stime;
- times->sum_exec_runtime = sig->sum_sched_runtime;
-
- rcu_read_lock();
- /* make sure we can trust tsk->thread_group list */
- if (!likely(pid_alive(tsk)))
- goto out;
-
- t = tsk;
- do {
- times->utime += t->utime;
- times->stime += t->stime;
- times->sum_exec_runtime += task_sched_runtime(t);
- } while_each_thread(tsk, t);
-out:
- rcu_read_unlock();
-}
-
static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b)
{
if (b->utime > a->utime)
diff --git a/kernel/sched/auto_group.c b/kernel/sched/auto_group.c
index 15f60d01198..0f1bacb005a 100644
--- a/kernel/sched/auto_group.c
+++ b/kernel/sched/auto_group.c
@@ -110,6 +110,9 @@ out_fail:
bool task_wants_autogroup(struct task_struct *p, struct task_group *tg)
{
+ if (!sysctl_sched_autogroup_enabled)
+ return false;
+
if (tg != &root_task_group)
return false;
@@ -155,8 +158,11 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag)
/* Allocates GFP_KERNEL, cannot be called under any spinlock */
void sched_autogroup_create_attach(struct task_struct *p)
{
- struct autogroup *ag = autogroup_create();
+ struct autogroup *ag;
+ if (!sysctl_sched_autogroup_enabled)
+ return;
+ ag = autogroup_create();
autogroup_move_group(p, ag);
/* drop extra reference added by autogroup_create() */
autogroup_kref_put(ag);
@@ -172,11 +178,15 @@ EXPORT_SYMBOL(sched_autogroup_detach);
void sched_autogroup_fork(struct signal_struct *sig)
{
+ if (!sysctl_sched_autogroup_enabled)
+ return;
sig->autogroup = autogroup_task_get(current);
}
void sched_autogroup_exit(struct signal_struct *sig)
{
+ if (!sysctl_sched_autogroup_enabled)
+ return;
autogroup_kref_put(sig->autogroup);
}
@@ -189,58 +199,6 @@ static int __init setup_autogroup(char *str)
__setup("noautogroup", setup_autogroup);
-#ifdef CONFIG_PROC_FS
-
-int proc_sched_autogroup_set_nice(struct task_struct *p, int nice)
-{
- static unsigned long next = INITIAL_JIFFIES;
- struct autogroup *ag;
- int err;
-
- if (nice < -20 || nice > 19)
- return -EINVAL;
-
- err = security_task_setnice(current, nice);
- if (err)
- return err;
-
- if (nice < 0 && !can_nice(current, nice))
- return -EPERM;
-
- /* this is a heavy operation taking global locks.. */
- if (!capable(CAP_SYS_ADMIN) && time_before(jiffies, next))
- return -EAGAIN;
-
- next = HZ / 10 + jiffies;
- ag = autogroup_task_get(p);
-
- down_write(&ag->lock);
- err = sched_group_set_shares(ag->tg, prio_to_weight[nice + 20]);
- if (!err)
- ag->nice = nice;
- up_write(&ag->lock);
-
- autogroup_kref_put(ag);
-
- return err;
-}
-
-void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m)
-{
- struct autogroup *ag = autogroup_task_get(p);
-
- if (!task_group_is_autogroup(ag->tg))
- goto out;
-
- down_read(&ag->lock);
- seq_printf(m, "/autogroup-%ld nice %d\n", ag->id, ag->nice);
- up_read(&ag->lock);
-
-out:
- autogroup_kref_put(ag);
-}
-#endif /* CONFIG_PROC_FS */
-
#ifdef CONFIG_SCHED_DEBUG
int autogroup_path(struct task_group *tg, char *buf, int buflen)
{
diff --git a/kernel/sched/auto_group.h b/kernel/sched/auto_group.h
index 443232ebbb5..4552c6bf79d 100644
--- a/kernel/sched/auto_group.h
+++ b/kernel/sched/auto_group.h
@@ -24,9 +24,7 @@ extern bool task_wants_autogroup(struct task_struct *p, struct task_group *tg);
static inline struct task_group *
autogroup_task_group(struct task_struct *p, struct task_group *tg)
{
- int enabled = ACCESS_ONCE(sysctl_sched_autogroup_enabled);
-
- if (enabled && task_wants_autogroup(p, tg))
+ if (task_wants_autogroup(p, tg))
return p->signal->autogroup->tg;
return tg;
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 8d859dae5be..b7f73176862 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -288,6 +288,34 @@ static __always_inline bool steal_account_process_tick(void)
return false;
}
+/*
+ * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
+ * tasks (sum on group iteration) belonging to @tsk's group.
+ */
+void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
+{
+ struct signal_struct *sig = tsk->signal;
+ struct task_struct *t;
+
+ times->utime = sig->utime;
+ times->stime = sig->stime;
+ times->sum_exec_runtime = sig->sum_sched_runtime;
+
+ rcu_read_lock();
+ /* make sure we can trust tsk->thread_group list */
+ if (!likely(pid_alive(tsk)))
+ goto out;
+
+ t = tsk;
+ do {
+ times->utime += t->utime;
+ times->stime += t->stime;
+ times->sum_exec_runtime += task_sched_runtime(t);
+ } while_each_thread(tsk, t);
+out:
+ rcu_read_unlock();
+}
+
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
@@ -417,13 +445,13 @@ void account_idle_ticks(unsigned long ticks)
* Use precise platform statistics if available:
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
-void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
*ut = p->utime;
*st = p->stime;
}
-void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
struct task_cputime cputime;
@@ -488,14 +516,30 @@ static cputime_t scale_utime(cputime_t utime, cputime_t rtime, cputime_t total)
return (__force cputime_t) temp;
}
-void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+/*
+ * Adjust tick based cputime random precision against scheduler
+ * runtime accounting.
+ */
+static void cputime_adjust(struct task_cputime *curr,
+ struct cputime *prev,
+ cputime_t *ut, cputime_t *st)
{
- cputime_t rtime, utime = p->utime, total = utime + p->stime;
+ cputime_t rtime, utime, total;
+
+ utime = curr->utime;
+ total = utime + curr->stime;
/*
- * Use CFS's precise accounting:
+ * Tick based cputime accounting depend on random scheduling
+ * timeslices of a task to be interrupted or not by the timer.
+ * Depending on these circumstances, the number of these interrupts
+ * may be over or under-optimistic, matching the real user and system
+ * cputime with a variable precision.
+ *
+ * Fix this by scaling these tick based values against the total
+ * runtime accounted by the CFS scheduler.
*/
- rtime = nsecs_to_cputime(p->se.sum_exec_runtime);
+ rtime = nsecs_to_cputime(curr->sum_exec_runtime);
if (total)
utime = scale_utime(utime, rtime, total);
@@ -503,38 +547,36 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
utime = rtime;
/*
- * Compare with previous values, to keep monotonicity:
+ * If the tick based count grows faster than the scheduler one,
+ * the result of the scaling may go backward.
+ * Let's enforce monotonicity.
*/
- p->prev_utime = max(p->prev_utime, utime);
- p->prev_stime = max(p->prev_stime, rtime - p->prev_utime);
+ prev->utime = max(prev->utime, utime);
+ prev->stime = max(prev->stime, rtime - prev->utime);
- *ut = p->prev_utime;
- *st = p->prev_stime;
+ *ut = prev->utime;
+ *st = prev->stime;
+}
+
+void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
+{
+ struct task_cputime cputime = {
+ .utime = p->utime,
+ .stime = p->stime,
+ .sum_exec_runtime = p->se.sum_exec_runtime,
+ };
+
+ cputime_adjust(&cputime, &p->prev_cputime, ut, st);
}
/*
* Must be called with siglock held.
*/
-void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
{
- struct signal_struct *sig = p->signal;
struct task_cputime cputime;
- cputime_t rtime, utime, total;
thread_group_cputime(p, &cputime);
-
- total = cputime.utime + cputime.stime;
- rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
-
- if (total)
- utime = scale_utime(cputime.utime, rtime, total);
- else
- utime = rtime;
-
- sig->prev_utime = max(sig->prev_utime, utime);
- sig->prev_stime = max(sig->prev_stime, rtime - sig->prev_utime);
-
- *ut = sig->prev_utime;
- *st = sig->prev_stime;
+ cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
}
#endif
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a319d56c760..59e072b2db9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3330,7 +3330,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
* Batch and idle tasks do not preempt non-idle tasks (their preemption
* is driven by the tick):
*/
- if (unlikely(p->policy != SCHED_NORMAL))
+ if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
return;
find_matching_se(&se, &pse);
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index eebefcad702..e68e69ab917 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -32,6 +32,11 @@ SCHED_FEAT(LAST_BUDDY, true)
SCHED_FEAT(CACHE_HOT_BUDDY, true)
/*
+ * Allow wakeup-time preemption of the current task:
+ */
+SCHED_FEAT(WAKEUP_PREEMPTION, true)
+
+/*
* Use arch dependent cpu power functions
*/
SCHED_FEAT(ARCH_POWER, true)
diff --git a/kernel/sys.c b/kernel/sys.c
index e6e0ece5f6a..265b3769042 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1046,7 +1046,7 @@ void do_sys_times(struct tms *tms)
cputime_t tgutime, tgstime, cutime, cstime;
spin_lock_irq(&current->sighand->siglock);
- thread_group_times(current, &tgutime, &tgstime);
+ thread_group_cputime_adjusted(current, &tgutime, &tgstime);
cutime = current->signal->cutime;
cstime = current->signal->cstime;
spin_unlock_irq(&current->sighand->siglock);
@@ -1704,7 +1704,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
utime = stime = 0;
if (who == RUSAGE_THREAD) {
- task_times(current, &utime, &stime);
+ task_cputime_adjusted(current, &utime, &stime);
accumulate_thread_rusage(p, r);
maxrss = p->signal->maxrss;
goto out;
@@ -1730,7 +1730,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
break;
case RUSAGE_SELF:
- thread_group_times(p, &tgutime, &tgstime);
+ thread_group_cputime_adjusted(p, &tgutime, &tgstime);
utime += tgutime;
stime += tgstime;
r->ru_nvcsw += p->signal->nvcsw;
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 26f65eaa01f..b0fa5ad0987 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -367,10 +367,8 @@ static struct ctl_table kern_table[] = {
.procname = "sched_autogroup_enabled",
.data = &sysctl_sched_autogroup_enabled,
.maxlen = sizeof(unsigned int),
- .mode = 0644,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = &zero,
- .extra2 = &one,
+ .mode = 0444,
+ .proc_handler = proc_dointvec,
},
#endif
#ifdef CONFIG_CFS_BANDWIDTH