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=-20.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham 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 07004C433FE for ; Thu, 9 Sep 2021 11:18:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C82C761104 for ; Thu, 9 Sep 2021 11:18:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235310AbhIILTv (ORCPT ); Thu, 9 Sep 2021 07:19:51 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:58550 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235410AbhIILTk (ORCPT ); Thu, 9 Sep 2021 07:19:40 -0400 Date: Thu, 09 Sep 2021 11:18:29 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1631186310; h=from:from:sender:sender:reply-to: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: in-reply-to:in-reply-to:references:references; bh=p6U+/WvyyC/TTJtJKu9eR22WdaUa7EJQ9pFcQXHusv0=; b=YlqJqOfN297q15OxBh+b2ERgDVre6Zs5fkB1xFqySBGQCLq0A3/+ZIQ9WuiHijrD4kr1v2 IC+M2yrAiN6T1GvL5vV5SPIgJYltK4hPIgC238ku1lIFvYEIqtXanBnIAiLf6JP+2ttGVU qebeTJtSS97hG7c/NEbYKEs5gjoZCd3ExWSB+YCyLFobzaIyRoUDwpWQIlDp/J52g0/CiE AnocZgoI2musK0iLgTVjshdPIDYlzGnrPvhhSryrWCaHipmNVssRhX7mfwkb0wxA+PPUbe L6/XAO3A/deTvRl6vB+N/R9c6Hlu6pQrYwGS1KbzymoRO5Iv3A2wyggMmlWelQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1631186310; h=from:from:sender:sender:reply-to: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: in-reply-to:in-reply-to:references:references; bh=p6U+/WvyyC/TTJtJKu9eR22WdaUa7EJQ9pFcQXHusv0=; b=ENu2ZrGzpevRhAI1Jl6HgFqE9dv40IUeqUC3TP99eQjZRg/yvF/elxGyL7BMW8pN6CfhYW OynHhyuJ0bLRsHDg== From: "tip-bot2 for Josh Don" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] fs/proc/uptime.c: Fix idle time reporting in /proc/uptime Cc: Luigi Rizzo , Josh Don , "Peter Zijlstra (Intel)" , Eric Dumazet , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210827165438.3280779-1-joshdon@google.com> References: <20210827165438.3280779-1-joshdon@google.com> MIME-Version: 1.0 Message-ID: <163118630930.25758.11716792020482050314.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: 1f74f9ea5a0cc9147f5bda4b5715ccb5cc34605d Gitweb: https://git.kernel.org/tip/1f74f9ea5a0cc9147f5bda4b5715ccb5cc34605d Author: Josh Don AuthorDate: Fri, 27 Aug 2021 09:54:38 -07:00 Committer: Peter Zijlstra CommitterDate: Thu, 09 Sep 2021 11:27:31 +02:00 fs/proc/uptime.c: Fix idle time reporting in /proc/uptime /proc/uptime reports idle time by reading the CPUTIME_IDLE field from the per-cpu kcpustats. However, on NO_HZ systems, idle time is not continually updated on idle cpus, leading this value to appear incorrectly small. /proc/stat performs an accounting update when reading idle time; we can use the same approach for uptime. With this patch, /proc/stat and /proc/uptime now agree on idle time. Additionally, the following shows idle time tick up consistently on an idle machine: (while true; do cat /proc/uptime; sleep 1; done) | awk '{print $2-prev; prev=$2}' Reported-by: Luigi Rizzo Signed-off-by: Josh Don Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Eric Dumazet Link: https://lkml.kernel.org/r/20210827165438.3280779-1-joshdon@google.com --- fs/proc/stat.c | 4 ++-- fs/proc/uptime.c | 14 +++++++++----- include/linux/kernel_stat.h | 1 + 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/fs/proc/stat.c b/fs/proc/stat.c index 6561a06..4fb8729 100644 --- a/fs/proc/stat.c +++ b/fs/proc/stat.c @@ -24,7 +24,7 @@ #ifdef arch_idle_time -static u64 get_idle_time(struct kernel_cpustat *kcs, int cpu) +u64 get_idle_time(struct kernel_cpustat *kcs, int cpu) { u64 idle; @@ -46,7 +46,7 @@ static u64 get_iowait_time(struct kernel_cpustat *kcs, int cpu) #else -static u64 get_idle_time(struct kernel_cpustat *kcs, int cpu) +u64 get_idle_time(struct kernel_cpustat *kcs, int cpu) { u64 idle, idle_usecs = -1ULL; diff --git a/fs/proc/uptime.c b/fs/proc/uptime.c index 5a1b228..deb99bc 100644 --- a/fs/proc/uptime.c +++ b/fs/proc/uptime.c @@ -12,18 +12,22 @@ static int uptime_proc_show(struct seq_file *m, void *v) { struct timespec64 uptime; struct timespec64 idle; - u64 nsec; + u64 idle_nsec; u32 rem; int i; - nsec = 0; - for_each_possible_cpu(i) - nsec += (__force u64) kcpustat_cpu(i).cpustat[CPUTIME_IDLE]; + idle_nsec = 0; + for_each_possible_cpu(i) { + struct kernel_cpustat kcs; + + kcpustat_cpu_fetch(&kcs, i); + idle_nsec += get_idle_time(&kcs, i); + } ktime_get_boottime_ts64(&uptime); timens_add_boottime(&uptime); - idle.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem); + idle.tv_sec = div_u64_rem(idle_nsec, NSEC_PER_SEC, &rem); idle.tv_nsec = rem; seq_printf(m, "%lu.%02lu %lu.%02lu\n", (unsigned long) uptime.tv_sec, diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h index 44ae1a7..69ae6b2 100644 --- a/include/linux/kernel_stat.h +++ b/include/linux/kernel_stat.h @@ -102,6 +102,7 @@ extern void account_system_index_time(struct task_struct *, u64, enum cpu_usage_stat); extern void account_steal_time(u64); extern void account_idle_time(u64); +extern u64 get_idle_time(struct kernel_cpustat *kcs, int cpu); #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE static inline void account_process_tick(struct task_struct *tsk, int user)