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Message-Id: <20241101031750.1471-3-laoar.shao@gmail.com>
Date: Fri, 1 Nov 2024 11:17:48 +0800
From: Yafang Shao <laoar.shao@...il.com>
To: mingo@...hat.com,
peterz@...radead.org
Cc: juri.lelli@...hat.com,
vincent.guittot@...aro.org,
dietmar.eggemann@....com,
rostedt@...dmis.org,
bsegall@...gle.com,
mgorman@...e.de,
vschneid@...hat.com,
hannes@...xchg.org,
surenb@...gle.com,
cgroups@...r.kernel.org,
linux-kernel@...r.kernel.org,
Yafang Shao <laoar.shao@...il.com>
Subject: [PATCH v4 2/4] sched: Don't account irq time if sched_clock_irqtime is disabled
sched_clock_irqtime may be disabled due to the clock source, in which case
IRQ time should not be accounted. Let's add a conditional check to avoid
unnecessary logic.
Signed-off-by: Yafang Shao <laoar.shao@...il.com>
---
kernel/sched/core.c | 44 +++++++++++++++++++++++---------------------
1 file changed, 23 insertions(+), 21 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index dbfb5717d6af..06a06f0897c3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -740,29 +740,31 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
s64 __maybe_unused steal = 0, irq_delta = 0;
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
- irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
+ if (static_branch_likely(&sched_clock_irqtime)) {
+ irq_delta = irq_time_read(cpu_of(rq)) - rq->prev_irq_time;
- /*
- * Since irq_time is only updated on {soft,}irq_exit, we might run into
- * this case when a previous update_rq_clock() happened inside a
- * {soft,}IRQ region.
- *
- * When this happens, we stop ->clock_task and only update the
- * prev_irq_time stamp to account for the part that fit, so that a next
- * update will consume the rest. This ensures ->clock_task is
- * monotonic.
- *
- * It does however cause some slight miss-attribution of {soft,}IRQ
- * time, a more accurate solution would be to update the irq_time using
- * the current rq->clock timestamp, except that would require using
- * atomic ops.
- */
- if (irq_delta > delta)
- irq_delta = delta;
+ /*
+ * Since irq_time is only updated on {soft,}irq_exit, we might run into
+ * this case when a previous update_rq_clock() happened inside a
+ * {soft,}IRQ region.
+ *
+ * When this happens, we stop ->clock_task and only update the
+ * prev_irq_time stamp to account for the part that fit, so that a next
+ * update will consume the rest. This ensures ->clock_task is
+ * monotonic.
+ *
+ * It does however cause some slight miss-attribution of {soft,}IRQ
+ * time, a more accurate solution would be to update the irq_time using
+ * the current rq->clock timestamp, except that would require using
+ * atomic ops.
+ */
+ if (irq_delta > delta)
+ irq_delta = delta;
- rq->prev_irq_time += irq_delta;
- delta -= irq_delta;
- delayacct_irq(rq->curr, irq_delta);
+ rq->prev_irq_time += irq_delta;
+ delta -= irq_delta;
+ delayacct_irq(rq->curr, irq_delta);
+ }
#endif
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
if (static_key_false((¶virt_steal_rq_enabled))) {
--
2.43.5
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