Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0A6AC433EF for ; Thu, 2 Dec 2021 14:12:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358419AbhLBOQD (ORCPT ); Thu, 2 Dec 2021 09:16:03 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:48618 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239448AbhLBOP7 (ORCPT ); Thu, 2 Dec 2021 09:15:59 -0500 Date: Thu, 02 Dec 2021 14:12:33 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1638454355; 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=NuFwk2J9Qv7//sgGcuDGt+74MdZfbJfLkF7V7ZFfUj8=; b=UONw5YVZquomqts/OANcejsap657H387QhVSJGh/5abTpG4+y8kTixsEwaDrGHaiJ6SMlC L7rS04kml13r0ogWUc03FM/9gNo0ilMue75F7YJBkbYdLUjm9qZzgmMR1EVHTfLLwRMzMs NDYjkBlQ5nktNEcZTFeYFlruKFwBFc9wORFOtW3mdvX/AFaeVfoFOaFQyAVGaUkvktPWpN XgZgpx7CyYMEP8AuG90i1WsA8s22VWDZBNXSdQzwqIb1urvzwagxcPS3rt8L7QmiTclt3S 0dB91AYFjP/EGtWzr9YOYR9F4Mug07nhUFGueKcxLGestSpCFLFUVoipTzW9Fg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1638454355; 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=NuFwk2J9Qv7//sgGcuDGt+74MdZfbJfLkF7V7ZFfUj8=; b=JXQtZ9F9dz/vPCO+bY4GzO7xP+R0C4FvhcqEZnz6JOfhYX04woFE3chKqaJwSN9rH3MLlP l0DTb/TNjRCizXAw== From: "tip-bot2 for Frederic Weisbecker" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] sched/cputime: Fix getrusage(RUSAGE_THREAD) with nohz_full Cc: Hasegawa Hitomi , Frederic Weisbecker , Thomas Gleixner , Masayoshi Mizuma , Phil Auld , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20211026141055.57358-3-frederic@kernel.org> References: <20211026141055.57358-3-frederic@kernel.org> MIME-Version: 1.0 Message-ID: <163845435389.11128.15096993127413247810.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/urgent branch of tip: Commit-ID: e7f2be115f0746b969c0df14c0d182f65f005ca5 Gitweb: https://git.kernel.org/tip/e7f2be115f0746b969c0df14c0d182f65f005ca5 Author: Frederic Weisbecker AuthorDate: Tue, 26 Oct 2021 16:10:55 +02:00 Committer: Thomas Gleixner CommitterDate: Thu, 02 Dec 2021 15:08:22 +01:00 sched/cputime: Fix getrusage(RUSAGE_THREAD) with nohz_full getrusage(RUSAGE_THREAD) with nohz_full may return shorter utime/stime than the actual time. task_cputime_adjusted() snapshots utime and stime and then adjust their sum to match the scheduler maintained cputime.sum_exec_runtime. Unfortunately in nohz_full, sum_exec_runtime is only updated once per second in the worst case, causing a discrepancy against utime and stime that can be updated anytime by the reader using vtime. To fix this situation, perform an update of cputime.sum_exec_runtime when the cputime snapshot reports the task as actually running while the tick is disabled. The related overhead is then contained within the relevant situations. Reported-by: Hasegawa Hitomi Signed-off-by: Frederic Weisbecker Signed-off-by: Hasegawa Hitomi Signed-off-by: Thomas Gleixner Tested-by: Masayoshi Mizuma Acked-by: Phil Auld Link: https://lore.kernel.org/r/20211026141055.57358-3-frederic@kernel.org --- include/linux/sched/cputime.h | 5 +++-- kernel/sched/cputime.c | 12 +++++++++--- 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/sched/cputime.h b/include/linux/sched/cputime.h index 6c9f19a..ce3c582 100644 --- a/include/linux/sched/cputime.h +++ b/include/linux/sched/cputime.h @@ -18,15 +18,16 @@ #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN -extern void task_cputime(struct task_struct *t, +extern bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime); extern u64 task_gtime(struct task_struct *t); #else -static inline void task_cputime(struct task_struct *t, +static inline bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime) { *utime = t->utime; *stime = t->stime; + return false; } static inline u64 task_gtime(struct task_struct *t) diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 872e481..9392aea 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -615,7 +615,8 @@ void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st) .sum_exec_runtime = p->se.sum_exec_runtime, }; - task_cputime(p, &cputime.utime, &cputime.stime); + if (task_cputime(p, &cputime.utime, &cputime.stime)) + cputime.sum_exec_runtime = task_sched_runtime(p); cputime_adjust(&cputime, &p->prev_cputime, ut, st); } EXPORT_SYMBOL_GPL(task_cputime_adjusted); @@ -828,19 +829,21 @@ u64 task_gtime(struct task_struct *t) * add up the pending nohz execution time since the last * cputime snapshot. */ -void task_cputime(struct task_struct *t, u64 *utime, u64 *stime) +bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime) { struct vtime *vtime = &t->vtime; unsigned int seq; u64 delta; + int ret; if (!vtime_accounting_enabled()) { *utime = t->utime; *stime = t->stime; - return; + return false; } do { + ret = false; seq = read_seqcount_begin(&vtime->seqcount); *utime = t->utime; @@ -850,6 +853,7 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime) if (vtime->state < VTIME_SYS) continue; + ret = true; delta = vtime_delta(vtime); /* @@ -861,6 +865,8 @@ void task_cputime(struct task_struct *t, u64 *utime, u64 *stime) else *utime += vtime->utime + delta; } while (read_seqcount_retry(&vtime->seqcount, seq)); + + return ret; } static int vtime_state_fetch(struct vtime *vtime, int cpu)