From c8ba971cf8567d49eb5f43ee90c4e50424331c18 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Fri, 8 May 2026 15:16:37 +0200 Subject: powerpc/time: Prepare to stop elapsing in dynticks-idle Currently the tick subsystem stores the idle cputime accounting in private fields, allowing cohabitation with architecture idle vtime accounting. The former is fetched on online CPUs, the latter on offline CPUs. For consolidation purpose, architecture vtime accounting will continue to account the cputime but will make a break when the idle tick is stopped. The dyntick cputime accounting will then be relayed by the tick subsystem so that the idle cputime is still seen advancing coherently even when the tick isn't there to flush the idle vtime. Prepare for that and introduce three new APIs which will be used in subsequent patches: - vtime_dynticks_start() is deemed to be called when idle enters in dyntick mode. The idle cputime that elapsed so far is accumulated. - vtime_dynticks_stop() is deemed to be called when idle exits from dyntick mode. The vtime entry clocks are fast-forward to current time so that idle accounting restarts elapsing from now. - vtime_reset() is deemed to be called from dynticks idle IRQ entry to fast-forward the clock to current time so that the IRQ time is still accounted by vtime while nohz cputime is paused. Also accumulated vtime won't be flushed from dyntick-idle ticks to avoid accounting twice the idle cputime, along with nohz accounting. Signed-off-by: Frederic Weisbecker Signed-off-by: Thomas Gleixner Tested-by: Shrikanth Hegde Reviewed-by: Shrikanth Hegde Link: https://patch.msgid.link/20260508131647.43868-6-frederic@kernel.org --- include/linux/vtime.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/vtime.h b/include/linux/vtime.h index 336875bea767..5516ad549e60 100644 --- a/include/linux/vtime.h +++ b/include/linux/vtime.h @@ -37,11 +37,17 @@ extern void vtime_account_irq(struct task_struct *tsk, unsigned int offset); extern void vtime_account_softirq(struct task_struct *tsk); extern void vtime_account_hardirq(struct task_struct *tsk); extern void vtime_flush(struct task_struct *tsk); +extern void vtime_reset(void); +extern void vtime_dyntick_start(void); +extern void vtime_dyntick_stop(void); #else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ static inline void vtime_account_irq(struct task_struct *tsk, unsigned int offset) { } static inline void vtime_account_softirq(struct task_struct *tsk) { } static inline void vtime_account_hardirq(struct task_struct *tsk) { } static inline void vtime_flush(struct task_struct *tsk) { } +static inline void vtime_reset(void) { } +static inline void vtime_dyntick_start(void) { } +static inline void vtime_dyntick_stop(void) { } #endif /* -- cgit v1.2.3