* [PATCH v2 0/2] Track loadavg changes during full nohz
@ 2020-01-11 9:53 Scott Wood
2020-01-11 9:53 ` [PATCH v2 1/2] sched/core: Don't skip remote tick for idle cpus Scott Wood
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Scott Wood @ 2020-01-11 9:53 UTC (permalink / raw)
To: Peter Zijlstra, Frederic Weisbecker, Thomas Gleixner, Ingo Molnar
Cc: linux-kernel
v2: drop the first couple patches that appear unnecessary
Peter Zijlstra (Intel) (1):
timers/nohz: Update nohz load in remote tick
Scott Wood (1):
sched/core: Don't skip remote tick for idle cpus
include/linux/sched/nohz.h | 2 ++
kernel/sched/core.c | 22 +++++++++++++---------
kernel/sched/loadavg.c | 33 +++++++++++++++++++++++----------
3 files changed, 38 insertions(+), 19 deletions(-)
--
1.8.3.1
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2 1/2] sched/core: Don't skip remote tick for idle cpus
2020-01-11 9:53 [PATCH v2 0/2] Track loadavg changes during full nohz Scott Wood
@ 2020-01-11 9:53 ` Scott Wood
2020-01-29 11:33 ` [tip: sched/core] sched/core: Don't skip remote tick for idle CPUs tip-bot2 for Scott Wood
2020-01-11 9:53 ` [PATCH v2 2/2] timers/nohz: Update nohz load in remote tick Scott Wood
2020-01-20 12:28 ` [PATCH v2 0/2] Track loadavg changes during full nohz Peter Zijlstra
2 siblings, 1 reply; 6+ messages in thread
From: Scott Wood @ 2020-01-11 9:53 UTC (permalink / raw)
To: Peter Zijlstra, Frederic Weisbecker, Thomas Gleixner, Ingo Molnar
Cc: linux-kernel, Scott Wood
This will be used in the next patch to get a loadavg update from
nohz cpus. The delta check is skipped because idle_sched_class
doesn't update se.exec_start.
Signed-off-by: Scott Wood <swood@redhat.com>
---
kernel/sched/core.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 90e4b00ace89..dfb8ea801700 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3668,22 +3668,24 @@ static void sched_tick_remote(struct work_struct *work)
* statistics and checks timeslices in a time-independent way, regardless
* of when exactly it is running.
*/
- if (idle_cpu(cpu) || !tick_nohz_tick_stopped_cpu(cpu))
+ if (!tick_nohz_tick_stopped_cpu(cpu))
goto out_requeue;
rq_lock_irq(rq, &rf);
curr = rq->curr;
- if (is_idle_task(curr) || cpu_is_offline(cpu))
+ if (cpu_is_offline(cpu))
goto out_unlock;
update_rq_clock(rq);
- delta = rq_clock_task(rq) - curr->se.exec_start;
- /*
- * Make sure the next tick runs within a reasonable
- * amount of time.
- */
- WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+ if (!is_idle_task(curr)) {
+ /*
+ * Make sure the next tick runs within a reasonable
+ * amount of time.
+ */
+ delta = rq_clock_task(rq) - curr->se.exec_start;
+ WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+ }
curr->sched_class->task_tick(rq, curr, 0);
out_unlock:
--
1.8.3.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 2/2] timers/nohz: Update nohz load in remote tick
2020-01-11 9:53 [PATCH v2 0/2] Track loadavg changes during full nohz Scott Wood
2020-01-11 9:53 ` [PATCH v2 1/2] sched/core: Don't skip remote tick for idle cpus Scott Wood
@ 2020-01-11 9:53 ` Scott Wood
2020-01-29 11:33 ` [tip: sched/core] timers/nohz: Update NOHZ " tip-bot2 for Peter Zijlstra (Intel)
2020-01-20 12:28 ` [PATCH v2 0/2] Track loadavg changes during full nohz Peter Zijlstra
2 siblings, 1 reply; 6+ messages in thread
From: Scott Wood @ 2020-01-11 9:53 UTC (permalink / raw)
To: Peter Zijlstra, Frederic Weisbecker, Thomas Gleixner, Ingo Molnar
Cc: linux-kernel, Scott Wood
From: "Peter Zijlstra (Intel)" <peterz@infradead.org>
The way loadavg is tracked during nohz only pays attention to the load
upon entering nohz. This can be particularly noticeable if full nohz is
entered while non-idle, and then the cpu goes idle and stays that way for
a long time.
Use the remote tick to ensure that full nohz cpus report their deltas
within a reasonable time.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[swood: added changelog and removed recheck of stopped tick]
Signed-off-by: Scott Wood <swood@redhat.com>
---
include/linux/sched/nohz.h | 2 ++
kernel/sched/core.c | 4 +++-
kernel/sched/loadavg.c | 33 +++++++++++++++++++++++----------
3 files changed, 28 insertions(+), 11 deletions(-)
diff --git a/include/linux/sched/nohz.h b/include/linux/sched/nohz.h
index 1abe91ff6e4a..6d67e9a5af6b 100644
--- a/include/linux/sched/nohz.h
+++ b/include/linux/sched/nohz.h
@@ -15,9 +15,11 @@ static inline void nohz_balance_enter_idle(int cpu) { }
#ifdef CONFIG_NO_HZ_COMMON
void calc_load_nohz_start(void);
+void calc_load_nohz_remote(struct rq *rq);
void calc_load_nohz_stop(void);
#else
static inline void calc_load_nohz_start(void) { }
+static inline void calc_load_nohz_remote(struct rq *rq) { }
static inline void calc_load_nohz_stop(void) { }
#endif /* CONFIG_NO_HZ_COMMON */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index dfb8ea801700..2e4a505e48af 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3676,6 +3676,7 @@ static void sched_tick_remote(struct work_struct *work)
if (cpu_is_offline(cpu))
goto out_unlock;
+ curr = rq->curr;
update_rq_clock(rq);
if (!is_idle_task(curr)) {
@@ -3688,10 +3689,11 @@ static void sched_tick_remote(struct work_struct *work)
}
curr->sched_class->task_tick(rq, curr, 0);
+ calc_load_nohz_remote(rq);
out_unlock:
rq_unlock_irq(rq, &rf);
-
out_requeue:
+
/*
* Run the remote tick once per second (1Hz). This arbitrary
* frequency is large enough to avoid overload but short enough
diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
index 28a516575c18..de22da666ac7 100644
--- a/kernel/sched/loadavg.c
+++ b/kernel/sched/loadavg.c
@@ -231,16 +231,11 @@ static inline int calc_load_read_idx(void)
return calc_load_idx & 1;
}
-void calc_load_nohz_start(void)
+static void calc_load_nohz_fold(struct rq *rq)
{
- struct rq *this_rq = this_rq();
long delta;
- /*
- * We're going into NO_HZ mode, if there's any pending delta, fold it
- * into the pending NO_HZ delta.
- */
- delta = calc_load_fold_active(this_rq, 0);
+ delta = calc_load_fold_active(rq, 0);
if (delta) {
int idx = calc_load_write_idx();
@@ -248,6 +243,24 @@ void calc_load_nohz_start(void)
}
}
+void calc_load_nohz_start(void)
+{
+ /*
+ * We're going into NO_HZ mode, if there's any pending delta, fold it
+ * into the pending NO_HZ delta.
+ */
+ calc_load_nohz_fold(this_rq());
+}
+
+/*
+ * Keep track of the load for NOHZ_FULL, must be called between
+ * calc_load_nohz_{start,stop}().
+ */
+void calc_load_nohz_remote(struct rq *rq)
+{
+ calc_load_nohz_fold(rq);
+}
+
void calc_load_nohz_stop(void)
{
struct rq *this_rq = this_rq();
@@ -268,7 +281,7 @@ void calc_load_nohz_stop(void)
this_rq->calc_load_update += LOAD_FREQ;
}
-static long calc_load_nohz_fold(void)
+static long calc_load_nohz_read(void)
{
int idx = calc_load_read_idx();
long delta = 0;
@@ -323,7 +336,7 @@ static void calc_global_nohz(void)
}
#else /* !CONFIG_NO_HZ_COMMON */
-static inline long calc_load_nohz_fold(void) { return 0; }
+static inline long calc_load_nohz_read(void) { return 0; }
static inline void calc_global_nohz(void) { }
#endif /* CONFIG_NO_HZ_COMMON */
@@ -346,7 +359,7 @@ void calc_global_load(unsigned long ticks)
/*
* Fold the 'old' NO_HZ-delta to include all NO_HZ CPUs.
*/
- delta = calc_load_nohz_fold();
+ delta = calc_load_nohz_read();
if (delta)
atomic_long_add(delta, &calc_load_tasks);
--
1.8.3.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 0/2] Track loadavg changes during full nohz
2020-01-11 9:53 [PATCH v2 0/2] Track loadavg changes during full nohz Scott Wood
2020-01-11 9:53 ` [PATCH v2 1/2] sched/core: Don't skip remote tick for idle cpus Scott Wood
2020-01-11 9:53 ` [PATCH v2 2/2] timers/nohz: Update nohz load in remote tick Scott Wood
@ 2020-01-20 12:28 ` Peter Zijlstra
2 siblings, 0 replies; 6+ messages in thread
From: Peter Zijlstra @ 2020-01-20 12:28 UTC (permalink / raw)
To: Scott Wood
Cc: Frederic Weisbecker, Thomas Gleixner, Ingo Molnar, linux-kernel
On Sat, Jan 11, 2020 at 04:53:37AM -0500, Scott Wood wrote:
> v2: drop the first couple patches that appear unnecessary
>
> Peter Zijlstra (Intel) (1):
> timers/nohz: Update nohz load in remote tick
>
> Scott Wood (1):
> sched/core: Don't skip remote tick for idle cpus
>
> include/linux/sched/nohz.h | 2 ++
> kernel/sched/core.c | 22 +++++++++++++---------
> kernel/sched/loadavg.c | 33 +++++++++++++++++++++++----------
> 3 files changed, 38 insertions(+), 19 deletions(-)
Thanks, I've queued them.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [tip: sched/core] sched/core: Don't skip remote tick for idle CPUs
2020-01-11 9:53 ` [PATCH v2 1/2] sched/core: Don't skip remote tick for idle cpus Scott Wood
@ 2020-01-29 11:33 ` tip-bot2 for Scott Wood
0 siblings, 0 replies; 6+ messages in thread
From: tip-bot2 for Scott Wood @ 2020-01-29 11:33 UTC (permalink / raw)
To: linux-tip-commits
Cc: Scott Wood, Peter Zijlstra (Intel), Ingo Molnar, x86, LKML
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 488603b815a7514c7009e6fc339d74ed4a30f343
Gitweb: https://git.kernel.org/tip/488603b815a7514c7009e6fc339d74ed4a30f343
Author: Scott Wood <swood@redhat.com>
AuthorDate: Sat, 11 Jan 2020 04:53:38 -05:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 28 Jan 2020 21:36:16 +01:00
sched/core: Don't skip remote tick for idle CPUs
This will be used in the next patch to get a loadavg update from
nohz cpus. The delta check is skipped because idle_sched_class
doesn't update se.exec_start.
Signed-off-by: Scott Wood <swood@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/1578736419-14628-2-git-send-email-swood@redhat.com
---
kernel/sched/core.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fc1dfc0..cf8b33d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3669,22 +3669,24 @@ static void sched_tick_remote(struct work_struct *work)
* statistics and checks timeslices in a time-independent way, regardless
* of when exactly it is running.
*/
- if (idle_cpu(cpu) || !tick_nohz_tick_stopped_cpu(cpu))
+ if (!tick_nohz_tick_stopped_cpu(cpu))
goto out_requeue;
rq_lock_irq(rq, &rf);
curr = rq->curr;
- if (is_idle_task(curr) || cpu_is_offline(cpu))
+ if (cpu_is_offline(cpu))
goto out_unlock;
update_rq_clock(rq);
- delta = rq_clock_task(rq) - curr->se.exec_start;
- /*
- * Make sure the next tick runs within a reasonable
- * amount of time.
- */
- WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+ if (!is_idle_task(curr)) {
+ /*
+ * Make sure the next tick runs within a reasonable
+ * amount of time.
+ */
+ delta = rq_clock_task(rq) - curr->se.exec_start;
+ WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+ }
curr->sched_class->task_tick(rq, curr, 0);
out_unlock:
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [tip: sched/core] timers/nohz: Update NOHZ load in remote tick
2020-01-11 9:53 ` [PATCH v2 2/2] timers/nohz: Update nohz load in remote tick Scott Wood
@ 2020-01-29 11:33 ` tip-bot2 for Peter Zijlstra (Intel)
0 siblings, 0 replies; 6+ messages in thread
From: tip-bot2 for Peter Zijlstra (Intel) @ 2020-01-29 11:33 UTC (permalink / raw)
To: linux-tip-commits
Cc: Peter Zijlstra (Intel), Scott Wood, Ingo Molnar, x86, LKML
The following commit has been merged into the sched/core branch of tip:
Commit-ID: ebc0f83c78a2d26384401ecf2d2fa48063c0ee27
Gitweb: https://git.kernel.org/tip/ebc0f83c78a2d26384401ecf2d2fa48063c0ee27
Author: Peter Zijlstra (Intel) <peterz@infradead.org>
AuthorDate: Sat, 11 Jan 2020 04:53:39 -05:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Tue, 28 Jan 2020 21:36:44 +01:00
timers/nohz: Update NOHZ load in remote tick
The way loadavg is tracked during nohz only pays attention to the load
upon entering nohz. This can be particularly noticeable if full nohz is
entered while non-idle, and then the cpu goes idle and stays that way for
a long time.
Use the remote tick to ensure that full nohz cpus report their deltas
within a reasonable time.
[ swood: Added changelog and removed recheck of stopped tick. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Scott Wood <swood@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/1578736419-14628-3-git-send-email-swood@redhat.com
---
include/linux/sched/nohz.h | 2 ++
kernel/sched/core.c | 4 +++-
kernel/sched/loadavg.c | 33 +++++++++++++++++++++++----------
3 files changed, 28 insertions(+), 11 deletions(-)
diff --git a/include/linux/sched/nohz.h b/include/linux/sched/nohz.h
index 1abe91f..6d67e9a 100644
--- a/include/linux/sched/nohz.h
+++ b/include/linux/sched/nohz.h
@@ -15,9 +15,11 @@ static inline void nohz_balance_enter_idle(int cpu) { }
#ifdef CONFIG_NO_HZ_COMMON
void calc_load_nohz_start(void);
+void calc_load_nohz_remote(struct rq *rq);
void calc_load_nohz_stop(void);
#else
static inline void calc_load_nohz_start(void) { }
+static inline void calc_load_nohz_remote(struct rq *rq) { }
static inline void calc_load_nohz_stop(void) { }
#endif /* CONFIG_NO_HZ_COMMON */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index cf8b33d..4ff03c2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3677,6 +3677,7 @@ static void sched_tick_remote(struct work_struct *work)
if (cpu_is_offline(cpu))
goto out_unlock;
+ curr = rq->curr;
update_rq_clock(rq);
if (!is_idle_task(curr)) {
@@ -3689,10 +3690,11 @@ static void sched_tick_remote(struct work_struct *work)
}
curr->sched_class->task_tick(rq, curr, 0);
+ calc_load_nohz_remote(rq);
out_unlock:
rq_unlock_irq(rq, &rf);
-
out_requeue:
+
/*
* Run the remote tick once per second (1Hz). This arbitrary
* frequency is large enough to avoid overload but short enough
diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c
index 28a5165..de22da6 100644
--- a/kernel/sched/loadavg.c
+++ b/kernel/sched/loadavg.c
@@ -231,16 +231,11 @@ static inline int calc_load_read_idx(void)
return calc_load_idx & 1;
}
-void calc_load_nohz_start(void)
+static void calc_load_nohz_fold(struct rq *rq)
{
- struct rq *this_rq = this_rq();
long delta;
- /*
- * We're going into NO_HZ mode, if there's any pending delta, fold it
- * into the pending NO_HZ delta.
- */
- delta = calc_load_fold_active(this_rq, 0);
+ delta = calc_load_fold_active(rq, 0);
if (delta) {
int idx = calc_load_write_idx();
@@ -248,6 +243,24 @@ void calc_load_nohz_start(void)
}
}
+void calc_load_nohz_start(void)
+{
+ /*
+ * We're going into NO_HZ mode, if there's any pending delta, fold it
+ * into the pending NO_HZ delta.
+ */
+ calc_load_nohz_fold(this_rq());
+}
+
+/*
+ * Keep track of the load for NOHZ_FULL, must be called between
+ * calc_load_nohz_{start,stop}().
+ */
+void calc_load_nohz_remote(struct rq *rq)
+{
+ calc_load_nohz_fold(rq);
+}
+
void calc_load_nohz_stop(void)
{
struct rq *this_rq = this_rq();
@@ -268,7 +281,7 @@ void calc_load_nohz_stop(void)
this_rq->calc_load_update += LOAD_FREQ;
}
-static long calc_load_nohz_fold(void)
+static long calc_load_nohz_read(void)
{
int idx = calc_load_read_idx();
long delta = 0;
@@ -323,7 +336,7 @@ static void calc_global_nohz(void)
}
#else /* !CONFIG_NO_HZ_COMMON */
-static inline long calc_load_nohz_fold(void) { return 0; }
+static inline long calc_load_nohz_read(void) { return 0; }
static inline void calc_global_nohz(void) { }
#endif /* CONFIG_NO_HZ_COMMON */
@@ -346,7 +359,7 @@ void calc_global_load(unsigned long ticks)
/*
* Fold the 'old' NO_HZ-delta to include all NO_HZ CPUs.
*/
- delta = calc_load_nohz_fold();
+ delta = calc_load_nohz_read();
if (delta)
atomic_long_add(delta, &calc_load_tasks);
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-01-29 11:33 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-11 9:53 [PATCH v2 0/2] Track loadavg changes during full nohz Scott Wood
2020-01-11 9:53 ` [PATCH v2 1/2] sched/core: Don't skip remote tick for idle cpus Scott Wood
2020-01-29 11:33 ` [tip: sched/core] sched/core: Don't skip remote tick for idle CPUs tip-bot2 for Scott Wood
2020-01-11 9:53 ` [PATCH v2 2/2] timers/nohz: Update nohz load in remote tick Scott Wood
2020-01-29 11:33 ` [tip: sched/core] timers/nohz: Update NOHZ " tip-bot2 for Peter Zijlstra (Intel)
2020-01-20 12:28 ` [PATCH v2 0/2] Track loadavg changes during full nohz Peter Zijlstra
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