On Fri, Jan 16, 2026 at 03:52:02PM +0100, Frederic Weisbecker wrote:

+static void kcpustat_idle_stop(struct kernel_cpustat *kc, ktime_t now)
 {
+	u64 *cpustat = kc->cpustat;
+	ktime_t delta;
+
+	if (!kc->idle_elapse)
+		return;
+
+	delta = ktime_sub(now, kc->idle_entrytime);
+
+	write_seqcount_begin(&kc->idle_sleeptime_seq);
+	if (nr_iowait_cpu(smp_processor_id()) > 0)
+		cpustat[CPUTIME_IOWAIT] = ktime_add(cpustat[CPUTIME_IOWAIT], delta);
+	else
+		cpustat[CPUTIME_IDLE] = ktime_add(cpustat[CPUTIME_IDLE], delta);
+
+	kc->idle_entrytime = now;
+	kc->idle_elapse = false;
+	write_seqcount_end(&kc->idle_sleeptime_seq);
 }

I realize this is mostly code movement; but do we really want to
preserve ktime_{sub,add}() and all that?

I mean, we killed that 32bit ktime nonsense ages ago.

-static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now)
-{
-	u64 *cpustat = kcpustat_this_cpu->cpustat;
-	ktime_t delta;
-
-	if (vtime_generic_enabled_this_cpu())
-		return;
-
-	if (WARN_ON_ONCE(!tick_sched_flag_test(ts, TS_FLAG_IDLE_ACTIVE)))
-		return;
-
-	delta = ktime_sub(now, ts->idle_entrytime);
-
-	write_seqcount_begin(&ts->idle_sleeptime_seq);
-	if (nr_iowait_cpu(smp_processor_id()) > 0)
-		cpustat[CPUTIME_IOWAIT] = ktime_add(cpustat[CPUTIME_IOWAIT], delta);
-	else
-		cpustat[CPUTIME_IDLE] = ktime_add(cpustat[CPUTIME_IDLE], delta);
-
-	ts->idle_entrytime = now;
-	tick_sched_flag_clear(ts, TS_FLAG_IDLE_ACTIVE);
-	write_seqcount_end(&ts->idle_sleeptime_seq);
-
-	sched_clock_idle_wakeup_event();
-}