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 CF325C433EF for ; Fri, 18 Mar 2022 14:48:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237910AbiCROtj (ORCPT ); Fri, 18 Mar 2022 10:49:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237826AbiCROsX (ORCPT ); Fri, 18 Mar 2022 10:48:23 -0400 Received: from imap2.colo.codethink.co.uk (imap2.colo.codethink.co.uk [78.40.148.184]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0378810505F for ; Fri, 18 Mar 2022 07:47:02 -0700 (PDT) Received: from cpc152649-stkp13-2-0-cust121.10-2.cable.virginm.net ([86.15.83.122] helo=[192.168.0.21]) by imap2.colo.codethink.co.uk with esmtpsa (Exim 4.92 #3 (Debian)) id 1nVDsT-0000OB-7s; Fri, 18 Mar 2022 14:46:53 +0000 Message-ID: Date: Fri, 18 Mar 2022 14:46:52 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH] RISC-V: Increase range and default value of NR_CPUS Content-Language: en-GB To: Anup Patel , Palmer Dabbelt , Paul Walmsley Cc: Atish Patra , Alistair Francis , Anup Patel , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org References: <20220317035542.272547-1-apatel@ventanamicro.com> From: Ben Dooks Organization: Codethink Limited. In-Reply-To: <20220317035542.272547-1-apatel@ventanamicro.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/03/2022 03:55, Anup Patel wrote: > Currently, the range and default value of NR_CPUS is too restrictive > for high-end RISC-V systems with large number of HARTs. The latest > QEMU virt machine supports upto 512 CPUs so the current NR_CPUS is > restrictive for QEMU as well. Other major architectures (such as > ARM64, x86_64, MIPS, etc) have a much higher range and default > value of NR_CPUS. What's the memory overhead for increasing this? -- Ben Dooks http://www.codethink.co.uk/ Senior Engineer Codethink - Providing Genius https://www.codethink.co.uk/privacy.html