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[2604:1380:4601:e00::3]) by mx.google.com with ESMTPS id t12-20020a50d70c000000b00553afbd5672si1294159edi.448.2024.01.12.02.56.59 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Jan 2024 02:56:59 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-24598-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=jjL2NtIw; dkim=neutral (no key) header.i=@linutronix.de header.s=2020e; spf=pass (google.com: domain of linux-kernel+bounces-24598-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) smtp.mailfrom="linux-kernel+bounces-24598-linux.lists.archive=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id F2AE71F255C0 for ; Fri, 12 Jan 2024 10:56:58 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6A4C75EE87; Fri, 12 Jan 2024 10:56:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="jjL2NtIw"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="WW890Bjy" Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 4E19958AB4 for ; Fri, 12 Jan 2024 10:56:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de From: Anna-Maria Behnsen DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1705057008; 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: in-reply-to:in-reply-to:references:references; bh=UbrBkxSGRtAZwyPLwAXR80o54hCAQ6NXr8R3T5x2vQE=; b=jjL2NtIwiWVTg0NofoOW164CxPy9Xwx4X8QW67HlhYixHGHgkLeyM5uik74dhEOGtVbmO+ G0+Uj+sQRvZ8wn837HFB798pQM0D7d34wa3yjcv+9fUqozU67kz8RWKesJic+lgZmpnG3f usyhS7uEwUR4OQMcHXxkHYgKKQE/HJWvfPryBZ18OigZOwMooMnIPZwaL12hOxoG6jo17V W/WphsucQ/SC869ajKj/zhBLQSWKio413QdSndJ9Mx9FzuGkxl0m5V9rOajAZSPNksYn+f 6Y3xxQekC4xkZMy6Ih8wThRaiaPfwAQxFLDB3iWl/8VAd78eDk14UwRZQmIA3A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1705057008; 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: in-reply-to:in-reply-to:references:references; bh=UbrBkxSGRtAZwyPLwAXR80o54hCAQ6NXr8R3T5x2vQE=; b=WW890Bjy+S5PgtnWwfW8Nwy0gYT+EClruZ172h4/g/C4ZWFoBmiYOxglmyz9QLJd2NxmWP kcQq0DAJmR++0rDQ== To: Pierre Gondois , linux-kernel@vger.kernel.org Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , Thomas Gleixner Subject: Re: [PATCH] sched/idle: Prevent stopping the tick when there is no cpuidle driver In-Reply-To: <06a2561f-557b-4eaa-8f11-75883bbbaef9@arm.com> References: <20231215130501.24542-1-anna-maria@linutronix.de> <87ttnmiif9.fsf@somnus> <06a2561f-557b-4eaa-8f11-75883bbbaef9@arm.com> Date: Fri, 12 Jan 2024 11:56:48 +0100 Message-ID: <87a5pag6q7.fsf@somnus> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Pierre Gondois writes: > Hello Anna-Maria, > > On 1/9/24 17:24, Anna-Maria Behnsen wrote: >> >> When there is no cpuidle driver, there is no instance which could bring >> the CPU into a deeper C state. But at the moment the code does >> unconditionally try to stop the tick. So the aim of the patch is to >> remove this unconditional stop of the tick. > > I agree that the absence of cpuidle driver prevents from reaching deep > idle states. FWIU, there is however still benefits in stopping the tick > on such platform. What's the benefit? Thanks, Anna-Maria