From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.alien8.de (mail.alien8.de [65.109.113.108]) (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 B03062D839B; Mon, 19 Jan 2026 10:22:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=65.109.113.108 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768818128; cv=none; b=ZJiHbEDBTUR8gq8QFaxRW/R6S3u7uCzgZ9cI87n0KEUdPYmHUTLtNfDCfArrbZ6WpO7b1nfrz8Y8dQtHGpaGCtceve7vYewAY7ZsWzekz7ny7RSymNGc4a4XfV2JPj3fJzFBMdjSU1t6wmZgi9B3PccSP+aI62ocMse7WbCKS5c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768818128; c=relaxed/simple; bh=bLu6RArehJiUjQ+SpX6+Ls76c2Qcb1yxoIJepWgJ1+A=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SCddRKAQOv6YUKJHPd4zu26TTVLjwvnvHfAba6s4EO6jeaDAhq8XsPS5/V95gr6rvlwvc78lYdUicsd4edHjQdlQaMO6rAtEzocyHV4QfHywieYS5Rk0ssoDGn2xwM/ZhZ3uYD216b/1Mm4kuZV6L0WFUrm8qLZkOOWT79qoOOU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de; spf=pass smtp.mailfrom=alien8.de; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b=FzC5NTJW; arc=none smtp.client-ip=65.109.113.108 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=alien8.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=alien8.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (4096-bit key) header.d=alien8.de header.i=@alien8.de header.b="FzC5NTJW" Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with ESMTP id 03A1640E02D2; Mon, 19 Jan 2026 10:22:00 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at mail.alien8.de Authentication-Results: mail.alien8.de (amavisd-new); dkim=pass (4096-bit key) header.d=alien8.de Received: from mail.alien8.de ([127.0.0.1]) by localhost (mail.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id lY5RUtm5OnD8; Mon, 19 Jan 2026 10:21:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=alien8; t=1768818115; bh=jNL1vZLUVDkOzUzJO9g2msnFYQBTSIcRRa9loxRJa/g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=FzC5NTJWyCp4sOjt3zlHWCjRuK7v0B9UhPDTMWlgCjd0rqG5bQobEExwFMTFBSXdR 7hlOoLLHfFtCg0+NgTFsISj6s7hkBj5dgiVhqBhMm3vMvv3xj/f6fFL6M2PQ4Qi1ZS XcZrb1m40zOR4+nR/uDFgybtJHwrjJJ/cFcVAbGzBgJgD2v4iykQy6AIRoXKzAufjy E0Pi2cR3mPFjOgHJlQe/FCsuYgqPQO0mlrl1JNQDDugFM/sDcaEHu88gM7DgXkYSMK 1oXK44hB1M34JfujY15zSqEc9in79mGtzAOoTlOoHBZYDThsBrbARlsaLHXjIBo8eP L7ASzPLvvFISAdQdjl464NMZRZVPo7OFxBLYoBZdol4SxOrVhvRSpRHPmIUPFJv9HR cIVUTwUbihsy4W7JxJSjvDGNg+cmXolD1JqfT4U9S2jUzqJp5styeiRKA9U4Ndnhpm D+0zJEJQ3cEuSrSbJ/eJ7kcsBCwQRF8bVcNPN7Jvl9ui+K9kljtp/kxkIpyWsvbSzH OktjxZbYNJrM4AcJeMiiX4tSPJ1yH0EUvCGqVny8x9xK9NQlDpfUHbtQKX1+8rhjLh NmAkjkhl7p98LLaavIeYk7O+Qpetzxg42KUrAw6HWEF75XX2RJcU6yhC7SID0RNAge wD0VOuY/pUucK22NjqFZkFA0= Received: from zn.tnic (pd953023b.dip0.t-ipconnect.de [217.83.2.59]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by mail.alien8.de (SuperMail on ZX Spectrum 128k) with UTF8SMTPSA id 6E7FD40E0028; Mon, 19 Jan 2026 10:21:25 +0000 (UTC) Date: Mon, 19 Jan 2026 11:21:16 +0100 From: Borislav Petkov To: Aaron Tomlin Cc: corbet@lwn.net, anna-maria@linutronix.de, frederic@kernel.org, tglx@kernel.org, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, akpm@linux-foundation.org, pawan.kumar.gupta@linux.intel.com, feng.tang@linux.alibaba.com, kees@kernel.org, elver@google.com, arnd@arndb.de, fvdl@google.com, lirongqing@baidu.com, bhelgaas@google.com, peterz@infradead.org, brgerst@gmail.com, kai.huang@intel.com, benjamin.berg@intel.com, andrew.cooper3@citrix.com, oleg@redhat.com, neelx@suse.com, sean@ashe.io, mproche@gmail.com, chjohnst@gmail.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/idle: Mark "idle=poll" as deprecated Message-ID: <20260119102116.GAaW4FnNBECNPFzAW3@fat_crate.local> References: <20260118231009.3194039-1-atomlin@atomlin.com> 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=utf-8 Content-Disposition: inline In-Reply-To: <20260118231009.3194039-1-atomlin@atomlin.com> On Sun, Jan 18, 2026 at 06:10:09PM -0500, Aaron Tomlin wrote: > The "idle=poll" boot parameter is a blunt instrument that forces all > CPUs in the system into a continuous "polling" state. While effective > at eliminating wake-up latency, this global override is architecturally > obsolete and inefficient on modern multicore systems. Nope. It is still very useful when you want to stop the machine from entering sleep states. > By writing special value "n/a" to the per-CPU sysfs node > /sys/devices/system/cpu/cpuN/power/pm_qos_resume_latency_us, userspace > can force a specific CPU to poll without imposing this cost globally. You can't do that on the kernel command line and thus prevent entering sleep states from the get-go. So no, it ain't broke so no need to fix it. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette