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 20F52C63798 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 BF907221FC for ; Tue, 17 Nov 2020 14:24:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="TdaeSuxP"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="nduu4VMI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728671AbgKQOYV (ORCPT ); Tue, 17 Nov 2020 09:24:21 -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 S1728593AbgKQOYT (ORCPT ); Tue, 17 Nov 2020 09:24:19 -0500 Message-Id: <20201117132006.565663056@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1605623058; 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=OhH7Vyhi+v7C8KGlTztCBlPjjTHSdhrCmDbeFrQSHVQ=; b=TdaeSuxP4PqQ20iAK9ZyVehhDkOFWcdOeiIUXrCoqFkR6gjyuv1j0DlT6iFj8fyQMPjNGh rAF+mOA5Mf5VpmM6MU34n3EHkeT4A0W+6PY4F6UmjHtj/9IHuMhzhEoLzcV8gPfs4uUu6t 4CP2aFWt1+bLNEOcfmBvQ2qypvKxY5V+2KstvjRRNMm4g1s/eQsb0YuTCi9bhg0J7JAqgO XUSG6FxkkrlwKT61PwSnBca9xZqbWFRJBkuK0xvps+M3SOQBqfnfAw53HBoVI5a4dze6qf T2AdlFXsg1nJ2R7F6b/MKF/IsYV75QOUMJnw05o3qrFZcr3yzTSbe/XSXNnLow== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1605623058; 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=OhH7Vyhi+v7C8KGlTztCBlPjjTHSdhrCmDbeFrQSHVQ=; b=nduu4VMIw9XKPh9YRZ+mXoPfrrGaQFxWyeaGyW419NjsqKKbfmguSx3k9/KX53uWTbJ2hk d6CCgRqCoEhrd9Cg== Date: Tue, 17 Nov 2020 14:19:47 +0100 From: Thomas Gleixner To: LKML Cc: Peter Zijlstra , Frederic Weisbecker , Yunfeng Ye Subject: [patch 5/7] tick/sched: Optimize tick_do_update_jiffies64() further 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 Now that it's clear that there is always one tick to account, simplify the calculations some more. Signed-off-by: Thomas Gleixner --- kernel/time/tick-sched.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -55,7 +55,7 @@ static ktime_t last_jiffies_update; */ static void tick_do_update_jiffies64(ktime_t now) { - unsigned long ticks = 0; + unsigned long ticks = 1; ktime_t delta; /* @@ -93,20 +93,21 @@ static void tick_do_update_jiffies64(kti write_seqcount_begin(&jiffies_seq); - last_jiffies_update = ktime_add(last_jiffies_update, tick_period); - delta = ktime_sub(now, tick_next_period); if (unlikely(delta >= tick_period)) { /* Slow path for long idle sleep times */ s64 incr = ktime_to_ns(tick_period); - ticks = ktime_divns(delta, incr); + 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); } - do_timer(++ticks); + do_timer(ticks); /* * Keep the tick_next_period variable up to date. WRITE_ONCE()