From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [78.32.30.218]) (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 C34A41C29C for ; Tue, 6 Feb 2024 23:18:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=78.32.30.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707261504; cv=none; b=TPqomC+AYckfzjeEfQC2DXLehOlMW7yHVkNdFvzQyMBW2fX2SWtDIySepDbjkIA1FrpVWDVf+Y/2yotpABHxYBqCgXh6h3KvMcv0nv643wB3QT/4X222C2wWXU4PemH+YNedHKxzqqDyflVE/Ir2/SfC7jg4NVGx8CIm+TpxoxE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707261504; c=relaxed/simple; bh=6k2/v7t4Lc7qS2f3uGGBR4lHof09wjKlY6e2xCdE8G8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UQsnfVeIcGIwGyN4rJBk5t1r7VOI5hI2pTwobDeYmDYicdIV8Hk4f5RAHfLNIykm42zFWazXqBUS6pAC1HM1zF6SmC4BIw1/dbfNyQhtg0A91npL3bisQCAz00603/N5PcdCS1a9kjYWpQ2k2e/QneeSDD68HCleg6aNk6Qu89k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk; spf=none smtp.mailfrom=armlinux.org.uk; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b=StElRlcS; arc=none smtp.client-ip=78.32.30.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=armlinux.org.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=armlinux.org.uk header.i=@armlinux.org.uk header.b="StElRlcS" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=DKdDlBaoWLD1i+SswtNzDM+hpIQ9ywhkR3LkK9m+G3w=; b=StElRlcSH9oSxj07zjDse4KeZb JMadwTYZgV3Oekw3j3odYlubfWwU2FxbHxxfvbtmPerYRfD2Fdz/rT5qsS/cYwagrYJqiUP9rnG6/ rRQnXey/kmQsTp1DUG7bi1vkNhSSGhbvkNmYGokw9mx12+pPUqUnMrLnZBFgzqIYXdZnfKAhL8isj 2S2hCuTWe5Mdcd19mk4IR4l80NSKrjqvRUpXfIfHS32mg01WRGowqs7MZbVshbCqrHQp/84zuJiIh TN1VWOm++QJRkeafxPtYvXNZAvhNga5IGoksfC4ys0rskp+Wol5sb4EV+vpkHX2Nh6+EhptKuBUMq bVdXUw0g==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:39202) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1rXUhY-0002bh-1q; Tue, 06 Feb 2024 23:18:04 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1rXUhS-00040V-VN; Tue, 06 Feb 2024 23:17:59 +0000 Date: Tue, 6 Feb 2024 23:17:58 +0000 From: "Russell King (Oracle)" To: "Christoph Lameter (Ampere)" Cc: catalin.marinas@arm.com, Will Deacon , Jonathan.Cameron@huawei.com, Matteo.Carlini@arm.com, Valentin.Schneider@arm.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, Eric Mackay , dave.kleikamp@oracle.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, robin.murphy@arm.com, vanshikonda@os.amperecomputing.com, yang@os.amperecomputing.com Subject: Re: [PATCH REPOST v2] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512 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=us-ascii Content-Disposition: inline In-Reply-To: Sender: Russell King (Oracle) On Tue, Feb 06, 2024 at 10:09:59AM -0800, Christoph Lameter (Ampere) wrote: > Can we get this merged for 6.9? The patch has been around for awhile now. > > > > Ampere Computing develops high end ARM processor that support an ever > increasing number of processors. The default 256 processors are > not enough for our newer products. The default is used by > distros and therefore our customers cannot use distro kernels because > the number of processors is not supported. > > One of the objections against earlier patches to increase the limit > was that the memory use becomes too high. There is a feature called > CPUMASK_OFFSTACK that configures the cpumasks in the kernel to be > dynamically allocated. This was used in the X86 architecture in the > past to enable support for larger CPU configurations up to 8k cpus. > > With that is becomes possible to dynamically size the allocation of > the cpu bitmaps depending on the quantity of processors detected on > bootup. > > This patch enables that logic if more than 256 processors > are configured and increases the default to 512 processors. > > Further increases may be needed if ARM processor vendors start > supporting more processors. Given the current inflationary trends > in core counts from multiple processor manufacturers this may occur. > > Tested-by: Eric Mackay Reviewed-by: Russell King (Oracle) Thanks! > Signed-off-by: Christoph Lameter (Ampere) -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!