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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B13BAC4167B for ; Thu, 7 Dec 2023 15:07:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1443227AbjLGPHP (ORCPT ); Thu, 7 Dec 2023 10:07:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235150AbjLGPHL (ORCPT ); Thu, 7 Dec 2023 10:07:11 -0500 Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75242D59 for ; Thu, 7 Dec 2023 07:07:16 -0800 (PST) Received: by mail-pf1-x432.google.com with SMTP id d2e1a72fcca58-6ce6dd83945so627664b3a.3 for ; Thu, 07 Dec 2023 07:07:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; t=1701961635; x=1702566435; darn=vger.kernel.org; h=to:cc:date:message-id:subject:mime-version :content-transfer-encoding:from:from:to:cc:subject:date:message-id :reply-to; bh=CZPF962lXavs4LecESKaTLt6HdfoXpSpOotG4VFvnDw=; b=ZkSn8+nWY96TbWvXxlSUIObuKhFfqK1LE+JiRG+o7OYrUNHtzgXOj2qp7QlVCr9FzR I3KPIVruxgAyD0+lOUawc7A8Lm1A3+Qn7P/klBoLFQmF0KroNKuoJS0E5Hvq9d2VBeC5 DwGXz2S74Oc8xmevRcKG8QQiT82nZ+tt+aUIid2V4pto+oBcprkULVtAIBwMJD7NKW1K O9xkmgkQRJSuHUEPs2KlavFVtB8/LXfjPNv3SPOPzpvsza+a8nMBHwwY2cqzmf6+4DTM v+lWXVqyZ/w7V7WcJGyE2hadnMgtKRAXr7RQxg9HPQHVjRaipZkaypZoWIWYoP9i3KmO eYXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701961635; x=1702566435; h=to:cc:date:message-id:subject:mime-version :content-transfer-encoding:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=CZPF962lXavs4LecESKaTLt6HdfoXpSpOotG4VFvnDw=; b=PZ1cKiVdQiZwGxVWHK8zDzsiGXIZsIQYTuv+wvcDGhkNA/cpNVQD/hujtD+0fw9oAY duTVQJ1jwH8D3zXDybR7wzzt4D7lDqPaHgaB8aGOPKvP/Pvpfhru0Cg9juXVZhiAxgbL T81NdSXfenD/1Yu7LcjHlvsZ1/0YRwWtErPZ+S32bgq12dfb15cMrepg7keXYKC0wX9s 1uYyIC/tiThUDYhvSLXK6bZ2vQbWi+8x3949+o5g2s2+AXNhfEpI+41aCjXXDEh8dwWU nieIsZgQS68SCBBvpHNiJy9KTs7ppHlpN+lH1TMsd3QqRvkZqcvG7hwv8zFeZIUl2/qI hZgA== X-Gm-Message-State: AOJu0Yw2Jf2zIwzysxlbhENiDTq2I9R+PwiQBcI82J73mRpyJeemV3yj ZpBi5xk7YKajRnwBoZBE0RR7zvfHDh7z7RrMAiHGlQ== X-Google-Smtp-Source: AGHT+IFeDLFm4/ox9OEcay0E+2CrGOLfCELaHKQrl+v+mFmvEF7verRHXrwXCmQBat0HYdXuSbkuDg== X-Received: by 2002:a05:6a20:2618:b0:18c:9855:e949 with SMTP id i24-20020a056a20261800b0018c9855e949mr2417031pze.15.1701961635507; Thu, 07 Dec 2023 07:07:15 -0800 (PST) Received: from smtpclient.apple ([2600:1700:63d0:ab90:5481:84fe:12c9:eb0e]) by smtp.gmail.com with ESMTPSA id e7-20020a056a001a8700b006ce4b40e7desm1452749pfv.90.2023.12.07.07.07.14 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 07 Dec 2023 07:07:15 -0800 (PST) From: Gianfranco Dutka Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.1\)) Subject: Modifying isolcpus, nohz_full, and rcu_nocb kernel parameters at runtime Message-Id: <76587DD3-2A77-41A3-9807-6AEE4398EBA6@arista.com> Date: Thu, 7 Dec 2023 10:07:13 -0500 Cc: vincent.guittot@linaro.com To: linux-kernel@vger.kernel.org X-Mailer: Apple Mail (2.3696.120.41.1.1) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Good afternoon maintainers and subscribers to the lkml,=20 I'm a bit new to kernel development but I had a question with respect to = the kernel parameters: isolcpus, nohz_full, and rcu_nocbs.=20 Basically the question is this, am I able to modify the three parameters = I mentioned above at runtime after the kernel has already = started/booted? Doing some reading online it seems that it=E2=80=99s not = possible but I wanted to double check with the maintainers if there = wasn=E2=80=99t some sort of change in the works that might make it = possible. If not, what would be required to make the change after = boot-time through some kind of patch or something like that? Would that = be something that might be valuable upstream? At the moment we are running an application that might see some benefit = from being able to isolate cpus on the fly without having to reboot = everything every time we want to modify the parameters mentioned above.=20= Thanks,=20 Gianfranco=