From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7D36CC64E75 for ; Tue, 17 Nov 2020 14:24:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F730221FC for ; Tue, 17 Nov 2020 14:24:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="JQViGrtf"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="bK6hgoV9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728746AbgKQOYY (ORCPT ); Tue, 17 Nov 2020 09:24:24 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:48778 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728593AbgKQOYW (ORCPT ); Tue, 17 Nov 2020 09:24:22 -0500 Message-Id: <20201117132006.766643526@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1605623060; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=36AbueCPRviT4pJmIguZZEcFRiUIP+ZE3fekX7M9B1s=; b=JQViGrtfMCrpuuz39trLdPQDptUJ4On3D8tV0uvq9xElvQZdMIsJ2HtuRQWOoZ5Ch1MtY/ RaYMI1SMigQ9k4+hjdp8of2FVaz18WSSAmB+c1Er2INrn4bssDL5hZ1t5NRMeipBGgNWnO TNlCj+GNrjd3GRrMqUiTafkss/AybcTl0s31OZTDQp7FHGhAaTWYVed1RBJ3V5aL+3Xei1 ThgT57DRPbfSXzzC0Dx8H2EsR1o2CtSeYlZtD0HlF29W0gCTOR9IPCLI1gSOUzmwOTtzxn FzdrIrgp+vb/02FNCnWE/AhVL89GzkGOyh1jV4JdUdcSMRA6R/V/7WOnf4T1Rg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1605623060; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=36AbueCPRviT4pJmIguZZEcFRiUIP+ZE3fekX7M9B1s=; b=bK6hgoV9t+X637a4dlPtQEXrTaoAR2Sl2H9tGAVuDb9u+ULlgvKhfe0AAs8UGzKJnZC83R NIZygVTNTS5GuwDA== Date: Tue, 17 Nov 2020 14:19:49 +0100 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Frederic Weisbecker , Yunfeng Ye Subject: [patch 7/7] tick: Get rid of tick_period References: <20201117131942.515430545@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The variable tick_period is initialized to NSEC_PER_TICK / HZ during boot and never updated again. If NSEC_PER_TICK is not an integer multiple of HZ this computation is less accurate than TICK_NSEC which has proper rounding in place. Aside of the inaccuracy there is no reason for having this variable at all. It's just a pointless indirection and all usage sites can just use the TICK_NSEC constant. Signed-off-by: Thomas Gleixner --- kernel/time/tick-broadcast.c | 2 +- kernel/time/tick-common.c | 8 +++----- kernel/time/tick-internal.h | 1 - kernel/time/tick-sched.c | 22 +++++++++++----------- 4 files changed, 15 insertions(+), 18 deletions(-) --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -331,7 +331,7 @@ static void tick_handle_periodic_broadca bc_local = tick_do_periodic_broadcast(); if (clockevent_state_oneshot(dev)) { - ktime_t next = ktime_add(dev->next_event, tick_period); + ktime_t next = ktime_add_ns(dev->next_event, TICK_NSEC); clockevents_program_event(dev, next, true); } --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -32,7 +32,6 @@ DEFINE_PER_CPU(struct tick_device, tick_ * no requirement to write hold the jiffies seqcount for it. */ ktime_t tick_next_period; -ktime_t tick_period; /* * tick_do_timer_cpu is a timer core internal variable which holds the CPU NR @@ -90,7 +89,7 @@ static void tick_periodic(int cpu) write_seqcount_begin(&jiffies_seq); /* Keep track of the next tick event */ - tick_next_period = ktime_add(tick_next_period, tick_period); + tick_next_period = ktime_add_ns(tick_next_period, TICK_NSEC); do_timer(1); write_seqcount_end(&jiffies_seq); @@ -129,7 +128,7 @@ void tick_handle_periodic(struct clock_e * Setup the next period for devices, which do not have * periodic mode: */ - next = ktime_add(next, tick_period); + next = ktime_add_ns(next, TICK_NSEC); if (!clockevents_program_event(dev, next, false)) return; @@ -175,7 +174,7 @@ void tick_setup_periodic(struct clock_ev for (;;) { if (!clockevents_program_event(dev, next, false)) return; - next = ktime_add(next, tick_period); + next = ktime_add_ns(next, TICK_NSEC); } } } @@ -222,7 +221,6 @@ static void tick_setup_device(struct tic tick_do_timer_cpu = cpu; tick_next_period = ktime_get(); - tick_period = NSEC_PER_SEC / HZ; #ifdef CONFIG_NO_HZ_FULL /* * The boot CPU may be nohz_full, in which case set --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -15,7 +15,6 @@ DECLARE_PER_CPU(struct tick_device, tick_cpu_device); extern ktime_t tick_next_period; -extern ktime_t tick_period; extern int tick_do_timer_cpu __read_mostly; extern void tick_setup_periodic(struct clock_event_device *dev, int broadcast); --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -95,17 +95,17 @@ static void tick_do_update_jiffies64(kti write_seqcount_begin(&jiffies_seq); delta = ktime_sub(now, tick_next_period); - if (unlikely(delta >= tick_period)) { + if (unlikely(delta >= TICK_NSEC)) { /* Slow path for long idle sleep times */ - s64 incr = ktime_to_ns(tick_period); + s64 incr = TICK_NSEC; ticks += ktime_divns(delta, incr); last_jiffies_update = ktime_add_ns(last_jiffies_update, incr * ticks); } else { - last_jiffies_update = ktime_add(last_jiffies_update, - tick_period); + last_jiffies_update = ktime_add_ns(last_jiffies_update, + TICK_NSEC); } /* Advance jiffies to complete the jiffies_seq protected job */ @@ -116,7 +116,7 @@ static void tick_do_update_jiffies64(kti * pairs with the READ_ONCE() in the lockless quick check above. */ WRITE_ONCE(tick_next_period, - ktime_add(last_jiffies_update, tick_period)); + ktime_add_ns(last_jiffies_update, TICK_NSEC)); /* * Release the sequence count. calc_global_load() below is not @@ -691,7 +691,7 @@ static void tick_nohz_restart(struct tic hrtimer_set_expires(&ts->sched_timer, ts->last_tick); /* Forward the time to expire in the future */ - hrtimer_forward(&ts->sched_timer, now, tick_period); + hrtimer_forward(&ts->sched_timer, now, TICK_NSEC); if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { hrtimer_start_expires(&ts->sched_timer, @@ -1260,7 +1260,7 @@ static void tick_nohz_handler(struct clo if (unlikely(ts->tick_stopped)) return; - hrtimer_forward(&ts->sched_timer, now, tick_period); + hrtimer_forward(&ts->sched_timer, now, TICK_NSEC); tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); } @@ -1297,7 +1297,7 @@ static void tick_nohz_switch_to_nohz(voi next = tick_init_jiffy_update(); hrtimer_set_expires(&ts->sched_timer, next); - hrtimer_forward_now(&ts->sched_timer, tick_period); + hrtimer_forward_now(&ts->sched_timer, TICK_NSEC); tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); tick_nohz_activate(ts, NOHZ_MODE_LOWRES); } @@ -1363,7 +1363,7 @@ static enum hrtimer_restart tick_sched_t if (unlikely(ts->tick_stopped)) return HRTIMER_NORESTART; - hrtimer_forward(timer, now, tick_period); + hrtimer_forward(timer, now, TICK_NSEC); return HRTIMER_RESTART; } @@ -1397,13 +1397,13 @@ void tick_setup_sched_timer(void) /* Offset the tick to avert jiffies_lock contention. */ if (sched_skew_tick) { - u64 offset = ktime_to_ns(tick_period) >> 1; + u64 offset = TICK_NSEC >> 1; do_div(offset, num_possible_cpus()); offset *= smp_processor_id(); hrtimer_add_expires_ns(&ts->sched_timer, offset); } - hrtimer_forward(&ts->sched_timer, now, tick_period); + hrtimer_forward(&ts->sched_timer, now, TICK_NSEC); hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED_HARD); tick_nohz_activate(ts, NOHZ_MODE_HIGHRES); }