From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 7B3BB1922C0 for ; Thu, 7 Aug 2025 12:42:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754570556; cv=none; b=YmdHcC6xe+P4YNkh3u6c4W7AKhtPQCmBcfCY1blXwunD7z1PmRwkBBOh2qVMuAbCnnYQpeMZI09baghPic9F6N0DquYJqsWGLMB5BMrtQDiFbRr88FHGAZMEh5glneQt7311NyKxB2cfBaS2fO41WCG5bC/xrcgNGgm1bJaaun0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754570556; c=relaxed/simple; bh=mm+ckMKaUNBCHWJjTNLnRTkIpATYJ1MOh5NvG+9Troc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jhO309jMqSyeXyLed4kmDRzEcDyLbAdg2QdDobOB+YpTVE/gH4PGvnyP4CBYZUj6L2gN+cNUQgtx4gxdd4P8mXFquYg4X0JX8iQZ7aaq4zTjZD7x/yyygWqQVaKpIjhnndTN5eYMdZilmFf/gAh7xHTv9tgoGZoicoeuh72/1Vk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KDQhDgSX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KDQhDgSX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0DB3C4CEEB; Thu, 7 Aug 2025 12:42:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754570556; bh=mm+ckMKaUNBCHWJjTNLnRTkIpATYJ1MOh5NvG+9Troc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KDQhDgSX8xUSILHFM70+/pzosDam28JaDJt3ui32V2/YorOnUImZFt4eECjzia4Oo 161DP4Va9z5eWk54JwqxXN2cZfkXDUd2nJws/Krv6SKzf/28R3wn5FO/D5RaD/AMml OsVQ8TlX1x9TKc7EAzZsaa0sMlM+4kQfezKlAKzDbmRBVBK7tO9ka1ZaoNzI2xodF9 70g+CdgjGT5mzLKlLlRWAmso16IR3j/XdmTlj8hOuEUzBG/i+CLOK7EbhL95qaHY0m 6qqarb96V+qCENWNVyJWFBBLn7Ya0HFrMSYA4c4sGqHyu948qIK7W61HatDohNosDG AJmtuEbE0jzTQ== Date: Thu, 7 Aug 2025 14:42:33 +0200 From: Frederic Weisbecker To: Gabriele Monaco Cc: linux-kernel@vger.kernel.org, Anna-Maria Behnsen , Thomas Gleixner , Waiman Long Subject: Re: [PATCH v10 1/8] timers/migration: Postpone online/offline callbacks registration to late initcall Message-ID: References: <20250806093855.86469-1-gmonaco@redhat.com> <20250806093855.86469-2-gmonaco@redhat.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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250806093855.86469-2-gmonaco@redhat.com> Le Wed, Aug 06, 2025 at 11:38:48AM +0200, Gabriele Monaco a écrit : > From: Frederic Weisbecker > > During the early boot process, the default clocksource used for > timekeeping is the jiffies. Better clocksources can only be selected > once clocksource_done_booting() is called as an fs initcall. > > NOHZ can only be enabled after that stage, making global timer migration > irrelevant up to that point. > > Therefore, don't bother with trashing the cache within that tree from > the SMP bootup until NOHZ even matters. I think I made a mistake with this sentence. Actually the timers are not propagated to the tree before nohz is enabled. So the sentence should actually be: "The tree remains inactive before NOHZ is enabled anyway. Therefore it makes sense to enable each CPUs to the tree only once that is setup." Thanks. -- Frederic Weisbecker SUSE Labs