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Wysocki" , Arjan van de Ven , "Paul E . McKenney" , Frederic Weisbecker , Rik van Riel , Steven Rostedt , Sebastian Siewior , Giovanni Gherdovich , Lukasz Luba , "Gautham R . Shenoy" , Srinivas Pandruvada , K Prateek Nayak , Anna-Maria Behnsen , Richard Cochran Subject: [PATCH v8 17/25] timer: Retrieve next expiry of pinned/non-pinned timers separately Date: Wed, 4 Oct 2023 14:34:46 +0200 Message-Id: <20231004123454.15691-18-anna-maria@linutronix.de> In-Reply-To: <20231004123454.15691-1-anna-maria@linutronix.de> References: <20231004123454.15691-1-anna-maria@linutronix.de> MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (snail.vger.email [0.0.0.0]); Wed, 04 Oct 2023 05:36:31 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1778828454013111903 X-GMAIL-MSGID: 1778828454013111903 For the conversion of the NOHZ timer placement to a pull at expiry time model it's required to have separate expiry times for the pinned and the non-pinned (movable) timers. Therefore struct timer_events is introduced. No functional change Originally-by: Richard Cochran (linutronix GmbH) Signed-off-by: Anna-Maria Behnsen Reviewed-by: Frederic Weisbecker --- kernel/time/timer.c | 48 ++++++++++++++++++++++++++++++++++----------- 1 file changed, 37 insertions(+), 11 deletions(-) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 1cd214c2f3f1..4230fc6fa1ed 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -221,6 +221,11 @@ struct timer_base { static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]); +struct timer_events { + u64 local; + u64 global; +}; + #ifdef CONFIG_NO_HZ_COMMON static DEFINE_STATIC_KEY_FALSE(timers_nohz_active); @@ -1971,9 +1976,10 @@ static unsigned long next_timer_interrupt(struct timer_base *base) return base->next_expiry; } -static inline unsigned long __get_next_timer_interrupt(unsigned long basej, +static inline unsigned long __get_next_timer_interrupt(unsigned long basej, u64 basem, struct timer_base *base_local, - struct timer_base *base_global) + struct timer_base *base_global, + struct timer_events *tevt) { unsigned long nextevt, nextevt_local, nextevt_global; bool local_first; @@ -1996,12 +2002,32 @@ static inline unsigned long __get_next_timer_interrupt(unsigned long basej, nextevt = local_first ? nextevt_local : nextevt_global; - if (base_local->timers_pending || base_global->timers_pending) { + /* + * If the @nextevt is at max. one tick away, use @nextevt and store + * it in the local expiry value. The next global event is irrelevant in + * this case and can be left as KTIME_MAX. + */ + if (time_before_eq(nextevt, basej + 1)) { /* If we missed a tick already, force 0 delta */ if (time_before(nextevt, basej)) nextevt = basej; + tevt->local = basem + (u64)(nextevt - basej) * TICK_NSEC; + return tevt->local; } + /* + * Update tevt->* values: + * + * If the local queue expires first, then the global event can + * be ignored. If the global queue is empty, nothing to do + * either. + */ + if (!local_first && base_global->timers_pending) + tevt->global = basem + (u64)(nextevt_global - basej) * TICK_NSEC; + + if (base_local->timers_pending) + tevt->local = basem + (u64)(nextevt_local - basej) * TICK_NSEC; + return nextevt; } @@ -2015,16 +2041,15 @@ static inline unsigned long __get_next_timer_interrupt(unsigned long basej, */ u64 get_next_timer_interrupt(unsigned long basej, u64 basem) { + struct timer_events tevt = { .local = KTIME_MAX, .global = KTIME_MAX }; struct timer_base *base_local, *base_global; - u64 expires = KTIME_MAX; - unsigned long nextevt; /* * Pretend that there is no timer pending if the cpu is offline. * Possible pending timers will be migrated later to an active cpu. */ if (cpu_is_offline(smp_processor_id())) - return expires; + return KTIME_MAX; base_local = this_cpu_ptr(&timer_bases[BASE_LOCAL]); base_global = this_cpu_ptr(&timer_bases[BASE_GLOBAL]); @@ -2032,14 +2057,14 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem) raw_spin_lock(&base_local->lock); raw_spin_lock_nested(&base_global->lock, SINGLE_DEPTH_NESTING); - nextevt = __get_next_timer_interrupt(basej, base_local, base_global); + __get_next_timer_interrupt(basej, basem, base_local, base_global, &tevt); raw_spin_unlock(&base_global->lock); raw_spin_unlock(&base_local->lock); - expires = basem + (u64)(nextevt - basej) * TICK_NSEC; + tevt.local = min_t(u64, tevt.local, tevt.global); - return cmp_next_hrtimer_event(basem, expires); + return cmp_next_hrtimer_event(basem, tevt.local); } /** @@ -2055,6 +2080,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem) */ u64 timer_set_idle(unsigned long basej, u64 basem, bool *idle) { + struct timer_events tevt = { .local = KTIME_MAX, .global = KTIME_MAX }; struct timer_base *base_local, *base_global; unsigned long nextevt; @@ -2073,7 +2099,7 @@ u64 timer_set_idle(unsigned long basej, u64 basem, bool *idle) raw_spin_lock(&base_local->lock); raw_spin_lock_nested(&base_global->lock, SINGLE_DEPTH_NESTING); - nextevt = __get_next_timer_interrupt(basej, base_local, base_global); + nextevt = __get_next_timer_interrupt(basej, basem, base_local, base_global, &tevt); /* * We have a fresh next event. Check whether we can forward the @@ -2097,7 +2123,7 @@ u64 timer_set_idle(unsigned long basej, u64 basem, bool *idle) raw_spin_unlock(&base_global->lock); raw_spin_unlock(&base_local->lock); - return basem + (u64)(nextevt - basej) * TICK_NSEC; + return min_t(u64, tevt.local, tevt.global); } /**