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authorLinus Torvalds <torvalds@linux-foundation.org>2017-07-09 10:52:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-07-09 10:52:16 -0700
commit4fde846ac0f019b7c877da35e1c1517d79e17ffc (patch)
treeee94559d13406f2ba29819fd3d0e6c4cc85ac174 /kernel
parentc3931a87db9e840dc20f3b962668d477eaeb2f75 (diff)
parent242fc35290bd8cf0effc6e3474e3a417985de2f3 (diff)
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner: "This scheduler update provides: - The (hopefully) final fix for the vtime accounting issues which were around for quite some time - Use types known to user space in UAPI headers to unbreak user space builds - Make load balancing respect the current scheduling domain again instead of evaluating unrelated CPUs" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/headers/uapi: Fix linux/sched/types.h userspace compilation errors sched/fair: Fix load_balance() affinity redo path sched/cputime: Accumulate vtime on top of nsec clocksource sched/cputime: Move the vtime task fields to their own struct sched/cputime: Rename vtime fields sched/cputime: Always set tsk->vtime_snap_whence after accounting vtime vtime, sched/cputime: Remove vtime_account_user() Revert "sched/cputime: Refactor the cputime_adjust() code"
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c6
-rw-r--r--kernel/sched/cputime.c180
-rw-r--r--kernel/sched/fair.c32
3 files changed, 134 insertions, 84 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index aa01b810c0bd..0f69a3e5281e 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1637,9 +1637,9 @@ static __latent_entropy struct task_struct *copy_process(
prev_cputime_init(&p->prev_cputime);
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
- seqcount_init(&p->vtime_seqcount);
- p->vtime_snap = 0;
- p->vtime_snap_whence = VTIME_INACTIVE;
+ seqcount_init(&p->vtime.seqcount);
+ p->vtime.starttime = 0;
+ p->vtime.state = VTIME_INACTIVE;
#endif
#if defined(SPLIT_RSS_COUNTING)
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 67c70e287647..6e3ea4ac1bda 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -611,17 +611,23 @@ static void cputime_adjust(struct task_cputime *curr,
utime = curr->utime;
/*
- * If either stime or both stime and utime are 0, assume all runtime is
- * userspace. Once a task gets some ticks, the monotonicy code at
- * 'update' will ensure things converge to the observed ratio.
+ * If either stime or utime are 0, assume all runtime is userspace.
+ * Once a task gets some ticks, the monotonicy code at 'update:'
+ * will ensure things converge to the observed ratio.
*/
- if (stime != 0) {
- if (utime == 0)
- stime = rtime;
- else
- stime = scale_stime(stime, rtime, stime + utime);
+ if (stime == 0) {
+ utime = rtime;
+ goto update;
}
+ if (utime == 0) {
+ stime = rtime;
+ goto update;
+ }
+
+ stime = scale_stime(stime, rtime, stime + utime);
+
+update:
/*
* Make sure stime doesn't go backwards; this preserves monotonicity
* for utime because rtime is monotonic.
@@ -673,20 +679,21 @@ void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
-static u64 vtime_delta(struct task_struct *tsk)
+static u64 vtime_delta(struct vtime *vtime)
{
- unsigned long now = READ_ONCE(jiffies);
+ unsigned long long clock;
- if (time_before(now, (unsigned long)tsk->vtime_snap))
+ clock = sched_clock_cpu(smp_processor_id());
+ if (clock < vtime->starttime)
return 0;
- return jiffies_to_nsecs(now - tsk->vtime_snap);
+ return clock - vtime->starttime;
}
-static u64 get_vtime_delta(struct task_struct *tsk)
+static u64 get_vtime_delta(struct vtime *vtime)
{
- unsigned long now = READ_ONCE(jiffies);
- u64 delta, other;
+ u64 delta = vtime_delta(vtime);
+ u64 other;
/*
* Unlike tick based timing, vtime based timing never has lost
@@ -695,104 +702,138 @@ static u64 get_vtime_delta(struct task_struct *tsk)
* elapsed time. Limit account_other_time to prevent rounding
* errors from causing elapsed vtime to go negative.
*/
- delta = jiffies_to_nsecs(now - tsk->vtime_snap);
other = account_other_time(delta);
- WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_INACTIVE);
- tsk->vtime_snap = now;
+ WARN_ON_ONCE(vtime->state == VTIME_INACTIVE);
+ vtime->starttime += delta;
return delta - other;
}
-static void __vtime_account_system(struct task_struct *tsk)
+static void __vtime_account_system(struct task_struct *tsk,
+ struct vtime *vtime)
+{
+ vtime->stime += get_vtime_delta(vtime);
+ if (vtime->stime >= TICK_NSEC) {
+ account_system_time(tsk, irq_count(), vtime->stime);
+ vtime->stime = 0;
+ }
+}
+
+static void vtime_account_guest(struct task_struct *tsk,
+ struct vtime *vtime)
{
- account_system_time(tsk, irq_count(), get_vtime_delta(tsk));
+ vtime->gtime += get_vtime_delta(vtime);
+ if (vtime->gtime >= TICK_NSEC) {
+ account_guest_time(tsk, vtime->gtime);
+ vtime->gtime = 0;
+ }
}
void vtime_account_system(struct task_struct *tsk)
{
- if (!vtime_delta(tsk))
+ struct vtime *vtime = &tsk->vtime;
+
+ if (!vtime_delta(vtime))
return;
- write_seqcount_begin(&tsk->vtime_seqcount);
- __vtime_account_system(tsk);
- write_seqcount_end(&tsk->vtime_seqcount);
+ write_seqcount_begin(&vtime->seqcount);
+ /* We might have scheduled out from guest path */
+ if (current->flags & PF_VCPU)
+ vtime_account_guest(tsk, vtime);
+ else
+ __vtime_account_system(tsk, vtime);
+ write_seqcount_end(&vtime->seqcount);
}
-void vtime_account_user(struct task_struct *tsk)
+void vtime_user_enter(struct task_struct *tsk)
{
- write_seqcount_begin(&tsk->vtime_seqcount);
- tsk->vtime_snap_whence = VTIME_SYS;
- if (vtime_delta(tsk))
- account_user_time(tsk, get_vtime_delta(tsk));
- write_seqcount_end(&tsk->vtime_seqcount);
+ struct vtime *vtime = &tsk->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ __vtime_account_system(tsk, vtime);
+ vtime->state = VTIME_USER;
+ write_seqcount_end(&vtime->seqcount);
}
-void vtime_user_enter(struct task_struct *tsk)
+void vtime_user_exit(struct task_struct *tsk)
{
- write_seqcount_begin(&tsk->vtime_seqcount);
- if (vtime_delta(tsk))
- __vtime_account_system(tsk);
- tsk->vtime_snap_whence = VTIME_USER;
- write_seqcount_end(&tsk->vtime_seqcount);
+ struct vtime *vtime = &tsk->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->utime += get_vtime_delta(vtime);
+ if (vtime->utime >= TICK_NSEC) {
+ account_user_time(tsk, vtime->utime);
+ vtime->utime = 0;
+ }
+ vtime->state = VTIME_SYS;
+ write_seqcount_end(&vtime->seqcount);
}
void vtime_guest_enter(struct task_struct *tsk)
{
+ struct vtime *vtime = &tsk->vtime;
/*
* The flags must be updated under the lock with
- * the vtime_snap flush and update.
+ * the vtime_starttime flush and update.
* That enforces a right ordering and update sequence
* synchronization against the reader (task_gtime())
* that can thus safely catch up with a tickless delta.
*/
- write_seqcount_begin(&tsk->vtime_seqcount);
- if (vtime_delta(tsk))
- __vtime_account_system(tsk);
+ write_seqcount_begin(&vtime->seqcount);
+ __vtime_account_system(tsk, vtime);
current->flags |= PF_VCPU;
- write_seqcount_end(&tsk->vtime_seqcount);
+ write_seqcount_end(&vtime->seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_enter);
void vtime_guest_exit(struct task_struct *tsk)
{
- write_seqcount_begin(&tsk->vtime_seqcount);
- __vtime_account_system(tsk);
+ struct vtime *vtime = &tsk->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ vtime_account_guest(tsk, vtime);
current->flags &= ~PF_VCPU;
- write_seqcount_end(&tsk->vtime_seqcount);
+ write_seqcount_end(&vtime->seqcount);
}
EXPORT_SYMBOL_GPL(vtime_guest_exit);
void vtime_account_idle(struct task_struct *tsk)
{
- account_idle_time(get_vtime_delta(tsk));
+ account_idle_time(get_vtime_delta(&tsk->vtime));
}
void arch_vtime_task_switch(struct task_struct *prev)
{
- write_seqcount_begin(&prev->vtime_seqcount);
- prev->vtime_snap_whence = VTIME_INACTIVE;
- write_seqcount_end(&prev->vtime_seqcount);
+ struct vtime *vtime = &prev->vtime;
+
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->state = VTIME_INACTIVE;
+ write_seqcount_end(&vtime->seqcount);
+
+ vtime = &current->vtime;
- write_seqcount_begin(&current->vtime_seqcount);
- current->vtime_snap_whence = VTIME_SYS;
- current->vtime_snap = jiffies;
- write_seqcount_end(&current->vtime_seqcount);
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->state = VTIME_SYS;
+ vtime->starttime = sched_clock_cpu(smp_processor_id());
+ write_seqcount_end(&vtime->seqcount);
}
void vtime_init_idle(struct task_struct *t, int cpu)
{
+ struct vtime *vtime = &t->vtime;
unsigned long flags;
local_irq_save(flags);
- write_seqcount_begin(&t->vtime_seqcount);
- t->vtime_snap_whence = VTIME_SYS;
- t->vtime_snap = jiffies;
- write_seqcount_end(&t->vtime_seqcount);
+ write_seqcount_begin(&vtime->seqcount);
+ vtime->state = VTIME_SYS;
+ vtime->starttime = sched_clock_cpu(cpu);
+ write_seqcount_end(&vtime->seqcount);
local_irq_restore(flags);
}
u64 task_gtime(struct task_struct *t)
{
+ struct vtime *vtime = &t->vtime;
unsigned int seq;
u64 gtime;
@@ -800,13 +841,13 @@ u64 task_gtime(struct task_struct *t)
return t->gtime;
do {
- seq = read_seqcount_begin(&t->vtime_seqcount);
+ seq = read_seqcount_begin(&vtime->seqcount);
gtime = t->gtime;
- if (t->vtime_snap_whence == VTIME_SYS && t->flags & PF_VCPU)
- gtime += vtime_delta(t);
+ if (vtime->state == VTIME_SYS && t->flags & PF_VCPU)
+ gtime += vtime->gtime + vtime_delta(vtime);
- } while (read_seqcount_retry(&t->vtime_seqcount, seq));
+ } while (read_seqcount_retry(&vtime->seqcount, seq));
return gtime;
}
@@ -818,8 +859,9 @@ u64 task_gtime(struct task_struct *t)
*/
void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
{
- u64 delta;
+ struct vtime *vtime = &t->vtime;
unsigned int seq;
+ u64 delta;
if (!vtime_accounting_enabled()) {
*utime = t->utime;
@@ -828,25 +870,25 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
}
do {
- seq = read_seqcount_begin(&t->vtime_seqcount);
+ seq = read_seqcount_begin(&vtime->seqcount);
*utime = t->utime;
*stime = t->stime;
/* Task is sleeping, nothing to add */
- if (t->vtime_snap_whence == VTIME_INACTIVE || is_idle_task(t))
+ if (vtime->state == VTIME_INACTIVE || is_idle_task(t))
continue;
- delta = vtime_delta(t);
+ delta = vtime_delta(vtime);
/*
* Task runs either in user or kernel space, add pending nohz time to
* the right place.
*/
- if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU)
- *utime += delta;
- else if (t->vtime_snap_whence == VTIME_SYS)
- *stime += delta;
- } while (read_seqcount_retry(&t->vtime_seqcount, seq));
+ if (vtime->state == VTIME_USER || t->flags & PF_VCPU)
+ *utime += vtime->utime + delta;
+ else if (vtime->state == VTIME_SYS)
+ *stime += vtime->stime + delta;
+ } while (read_seqcount_retry(&vtime->seqcount, seq));
}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 008c514dc241..c95880e216f6 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6646,10 +6646,10 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
* our sched_group. We may want to revisit it if we couldn't
* meet load balance goals by pulling other tasks on src_cpu.
*
- * Also avoid computing new_dst_cpu if we have already computed
- * one in current iteration.
+ * Avoid computing new_dst_cpu for NEWLY_IDLE or if we have
+ * already computed one in current iteration.
*/
- if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED))
+ if (env->idle == CPU_NEWLY_IDLE || (env->flags & LBF_DST_PINNED))
return 0;
/* Prevent to re-select dst_cpu via env's cpus */
@@ -8022,14 +8022,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,
.tasks = LIST_HEAD_INIT(env.tasks),
};
- /*
- * For NEWLY_IDLE load_balancing, we don't need to consider
- * other cpus in our group
- */
- if (idle == CPU_NEWLY_IDLE)
- env.dst_grpmask = NULL;
-
- cpumask_copy(cpus, cpu_active_mask);
+ cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask);
schedstat_inc(sd->lb_count[idle]);
@@ -8151,7 +8144,15 @@ more_balance:
/* All tasks on this runqueue were pinned by CPU affinity */
if (unlikely(env.flags & LBF_ALL_PINNED)) {
cpumask_clear_cpu(cpu_of(busiest), cpus);
- if (!cpumask_empty(cpus)) {
+ /*
+ * Attempting to continue load balancing at the current
+ * sched_domain level only makes sense if there are
+ * active CPUs remaining as possible busiest CPUs to
+ * pull load from which are not contained within the
+ * destination group that is receiving any migrated
+ * load.
+ */
+ if (!cpumask_subset(cpus, env.dst_grpmask)) {
env.loop = 0;
env.loop_break = sched_nr_migrate_break;
goto redo;
@@ -8447,6 +8448,13 @@ static int active_load_balance_cpu_stop(void *data)
.src_cpu = busiest_rq->cpu,
.src_rq = busiest_rq,
.idle = CPU_IDLE,
+ /*
+ * can_migrate_task() doesn't need to compute new_dst_cpu
+ * for active balancing. Since we have CPU_IDLE, but no
+ * @dst_grpmask we need to make that test go away with lying
+ * about DST_PINNED.
+ */
+ .flags = LBF_DST_PINNED,
};
schedstat_inc(sd->alb_count);