The following commit has been merged into the sched/core branch of tip:
Commit-ID: 763a744e24a8cfbcc13f699dcdae13a627b8588e
Gitweb: https://git.kernel.org/tip/763a744e24a8cfbcc13f699dcdae13a627b8588e
Author: Yafang Shao <laoar.shao@xxxxxxxxx>
AuthorDate: Fri, 03 Jan 2025 10:24:07 +08:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 13 Jan 2025 14:10:25 +01:00
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@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Michal Koutný <mkoutny@xxxxxxxx>
Reviewed-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20250103022409.2544-3-laoar.shao@xxxxxxxxx
---
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 8490293..22dfcd3 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 (irqtime_enabled()) {
+ 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))) {
|