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Sat, 21 Dec 2024 18:47:57 -0800 (PST) From: Yafang Shao To: mingo@redhat.com, peterz@infradead.org, mkoutny@suse.com, hannes@cmpxchg.org Cc: juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, surenb@google.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, lkp@intel.com, Yafang Shao Subject: [PATCH v8 1/4] sched: Define sched_clock_irqtime as static key Date: Sun, 22 Dec 2024 10:47:31 +0800 Message-Id: <20241222024734.63894-2-laoar.shao@gmail.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20241222024734.63894-1-laoar.shao@gmail.com> References: <20241222024734.63894-1-laoar.shao@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since CPU time accounting is a performance-critical path, let's define sched_clock_irqtime as a static key to minimize potential overhead. Signed-off-by: Yafang Shao Reviewed-by: Michal Koutný --- kernel/sched/cputime.c | 16 +++++++--------- kernel/sched/sched.h | 13 +++++++++++++ 2 files changed, 20 insertions(+), 9 deletions(-) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 0bed0fa1acd9..5d9143dd0879 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -9,6 +9,8 @@ #ifdef CONFIG_IRQ_TIME_ACCOUNTING +DEFINE_STATIC_KEY_FALSE(sched_clock_irqtime); + /* * There are no locks covering percpu hardirq/softirq time. * They are only modified in vtime_account, on corresponding CPU @@ -22,16 +24,14 @@ */ DEFINE_PER_CPU(struct irqtime, cpu_irqtime); -static int sched_clock_irqtime; - void enable_sched_clock_irqtime(void) { - sched_clock_irqtime = 1; + static_branch_enable(&sched_clock_irqtime); } void disable_sched_clock_irqtime(void) { - sched_clock_irqtime = 0; + static_branch_disable(&sched_clock_irqtime); } static void irqtime_account_delta(struct irqtime *irqtime, u64 delta, @@ -57,7 +57,7 @@ void irqtime_account_irq(struct task_struct *curr, unsigned int offset) s64 delta; int cpu; - if (!sched_clock_irqtime) + if (!irqtime_enabled()) return; cpu = smp_processor_id(); @@ -90,8 +90,6 @@ static u64 irqtime_tick_accounted(u64 maxtime) #else /* CONFIG_IRQ_TIME_ACCOUNTING */ -#define sched_clock_irqtime (0) - static u64 irqtime_tick_accounted(u64 dummy) { return 0; @@ -478,7 +476,7 @@ void account_process_tick(struct task_struct *p, int user_tick) if (vtime_accounting_enabled_this_cpu()) return; - if (sched_clock_irqtime) { + if (irqtime_enabled()) { irqtime_account_process_tick(p, user_tick, 1); return; } @@ -507,7 +505,7 @@ void account_idle_ticks(unsigned long ticks) { u64 cputime, steal; - if (sched_clock_irqtime) { + if (irqtime_enabled()) { irqtime_account_idle_ticks(ticks); return; } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index aef716c41edb..7e8c73110884 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -3233,6 +3233,12 @@ struct irqtime { }; DECLARE_PER_CPU(struct irqtime, cpu_irqtime); +DECLARE_STATIC_KEY_FALSE(sched_clock_irqtime); + +static inline int irqtime_enabled(void) +{ + return static_branch_likely(&sched_clock_irqtime); +} /* * Returns the irqtime minus the softirq time computed by ksoftirqd. @@ -3253,6 +3259,13 @@ static inline u64 irq_time_read(int cpu) return total; } +#else + +static inline int irqtime_enabled(void) +{ + return 0; +} + #endif /* CONFIG_IRQ_TIME_ACCOUNTING */ #ifdef CONFIG_CPU_FREQ -- 2.43.5