From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EF67E545291 for ; Tue, 22 Sep 2026 12:53:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790081600; cv=none; b=j0TCZpQe9lXmOt2fGMxYH00As/SDKCRO8wN0p0QJzX7oJhPEiiUxz9jtOpNj4no3sbPICMLwSX6/C47OzLxMvioUlTu8UpO6/OuFLTaS6GocJYh0D84G369KekZtYac7xqwNI+ytiWRmldyFf9OurbqYJ/nUtbSD6VjAxj2Awck= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790081600; c=relaxed/simple; bh=qyFdaEgNEWQjqDPze6zuBU++M1/H9oQ7ulVcqDoDcBw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=vDogWM9qEWbzPz4gv2cHi2KVtiTukloBcsDZA3PxYz+YkykIiOJU80JrTyiozOQrvuGJxDZXUDCZg3SyO3LX4Lri+h9GfLblpFAkJ1+CUQrsTwis59r1gfxScEcrin8N9hELY7Wb4TQ+ThhXMdcXr4AgXc+2+dB9cVCOvuFvwPI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DoKGIk48; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="DoKGIk48" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3B0A1F000FF; Tue, 22 Sep 2026 12:53:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790081593; bh=+c9dYd91MT3vXguF9zyMvY4hnXR9KLof6KH9MAchdIs=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=DoKGIk48OrIs8sM7z6x4ISaR7I78vam1KFF0vlN8jeWAQePzjW1xVkKvGcvE0We/0 pJ+6jYc2Kp/w9QkmPF5fekg0Ahn/2NIVAyc0tOKy7AoHF5LCDzgq0c75gF1kngoikt KBDTCUQsc4r1XyI0I7tgeUda6inACoF6HaUZT1uykp5zpznsKWw83D8hmJYQm34yVN YWe1X8dK70OLhxu6TMCKvpGxlXH5d+1qOqe9Vyc3m3CDTBQ4IellhuyrE+aH5WOxAz wwG83bnpoI1gZtKvIHwDzTt3/5lbXiEtd56SmRAZaVsfMcqDsR34EC4QTj1LalTXbi LJBAomB2V+w2A== Date: Tue, 22 Sep 2026 14:53:10 +0200 From: Frederic Weisbecker To: Ahmed Shaltout Cc: tglx@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [REGRESSION] /proc/stat idle time exceeds wall clock since v7.2 Message-ID: References: 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Hi Ahmed, Le Sun, Sep 20, 2026 at 03:14:22AM +0400, Ahmed Shaltout a écrit : > Hello, > > Since moving from 7.1.8 to 7.2.5 (openSUSE MicroOS kernel-default), the idle > time reported in /proc/stat exceeds the wall-clock time the CPUs have been up > for. Idle alone accrues ~103% of the ceiling, and user+nice+system+idle+iowait > +irq+softirq+steal sums to ~108% of it. > > This breaks the common `100 - rate(idle)` derivation of CPU utilisation, which > goes negative on an idle-but-working machine. node_exporter, and anything built > on it, is affected. > > #regzbot introduced: v7.1..v7.2 > > Reproducer > ========== > > No tooling needed; /proc/uptime shows it directly, since its second field is > idle time and cannot legitimately exceed uptime x nr_cpus: > > read -r up idle < /proc/uptime && awk -v u="$up" -v i="$idle" -v c="$(nproc)" \ > 'BEGIN{printf "idle %.2f%% of ceiling\n", 100*i/(u*c)}' > > 7.2.5: idle 103.10% of ceiling > 7.1.8: idle 89.13% of ceiling I can't manage to reproduce that, neither on latest mainline nor on 7.2.7 Can you share your whole .config file? Thanks. -- Frederic Weisbecker SUSE Labs