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sched, psi: Don't account irq time if sched_clock_irqtime is disabled

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sched_clock_irqtime may be disabled due to the clock source. When disabled,
irq_time_read() won't change over time, so there is nothing to account. We
can save iterating the whole hierarchy on every tick and context switch.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20250103022409.2544-4-laoar.shao@gmail.com
This commit is contained in:
Yafang Shao 2025-01-03 10:24:08 +08:00 committed by Peter Zijlstra
parent 763a744e24
commit a6fd16148f
1 changed files with 6 additions and 1 deletions
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7
kernel/sched/psi.c
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@ -998,7 +998,7 @@ void psi_account_irqtime(struct rq *rq, struct task_struct *curr, struct task_st
s64 delta;
u64 irq;
if (static_branch_likely(&psi_disabled))
if (static_branch_likely(&psi_disabled) || !irqtime_enabled())
return;
if (!curr->pid)
@ -1240,6 +1240,11 @@ int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
if (static_branch_likely(&psi_disabled))
return -EOPNOTSUPP;
#ifdef CONFIG_IRQ_TIME_ACCOUNTING
if (!irqtime_enabled() && res == PSI_IRQ)
return -EOPNOTSUPP;
#endif
/* Update averages before reporting them */
mutex_lock(&group->avgs_lock);
now = sched_clock();