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 6CF5956B7F for ; Mon, 18 Mar 2024 18:17:28 +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=1710785848; cv=none; b=azQqX6UTxUdqk+T77snOZbSAnG5zWnj51no0tJ61DaHYWUVW8OgHqWS/0pdZ/meCKzqNfBPE0G/gVptt43O4yjB0CC4ckqtYRoqWSQ6FzxT2x4ziee7utiRB5ym8JM4v3U016bwp7jxv+jfps3c9fZLtH/7yzHgfqIOyzQpCK2g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710785848; c=relaxed/simple; bh=wpz+jpXp1/xLYY8u8ro7WOlKUYxshynrXNl0hjCDdXc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=joO3HKm/v4ryyEzfF63mxgkhDWvsneWj4S3JDGyWyWqsJkHH6Ewh2YVZN8EvFy4TXMznwyqHe9BX5HvPcZaC4lMLpfZfgfJWqZqjg1E7o5p3/8jc845t65MV8jqeFxIdxwEmcTYMPsYezWssLGHYLcD1UTDG3CE/b1d3XSCJgpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9D78C433C7; Mon, 18 Mar 2024 18:17:24 +0000 (UTC) Date: Mon, 18 Mar 2024 18:17:22 +0000 From: Catalin Marinas To: Mark Rutland , "Christoph Lameter (Ampere)" Cc: Will Deacon , Jonathan.Cameron@huawei.com, Matteo.Carlini@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, linux@armlinux.org.uk, robin.murphy@arm.com, vanshikonda@os.amperecomputing.com, yang@os.amperecomputing.com, Valentin Schneider Subject: Re: [PATCH v3] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512 Message-ID: References: <37099a57-b655-3b3a-56d0-5f7fbd49d7db@gentwo.org> <170983839495.1825460.8461454086733296317.b4-ty@arm.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=us-ascii Content-Disposition: inline In-Reply-To: <170983839495.1825460.8461454086733296317.b4-ty@arm.com> On Thu, Mar 07, 2024 at 07:07:07PM +0000, Catalin Marinas wrote: > On Wed, 06 Mar 2024 17:45:04 -0800, Christoph Lameter (Ampere) wrote: > > Currently defconfig selects NR_CPUS=256, but some vendors (e.g. Ampere > > Computing) are planning to ship systems with 512 CPUs. So that all CPUs on > > these systems can be used with defconfig, we'd like to bump NR_CPUS to 512. > > Therefore this patch increases the default NR_CPUS from 256 to 512. > > > > As increasing NR_CPUS will increase the size of cpumasks, there's a fear that > > this might have a significant impact on stack usage due to code which places > > cpumasks on the stack. To mitigate that concern, we can select > > CPUMASK_OFFSTACK. As that doesn't seem to be a problem today with > > NR_CPUS=256, we only select this when NR_CPUS > 256. > > > > [...] > > Applied to arm64 (for-next/misc), thanks! > > I dropped the config entry and comment, replaced it with a select as per > Mark's suggestion. > > [1/1] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512 > https://git.kernel.org/arm64/c/0499a78369ad I re-instated this patch in arm64 for-next/core as: https://git.kernel.org/arm64/c/3fbd56f0e7c1 -- Catalin