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 02702ECAAD5 for ; Tue, 6 Sep 2022 15:24:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239945AbiIFPYg (ORCPT ); Tue, 6 Sep 2022 11:24:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239171AbiIFPX7 (ORCPT ); Tue, 6 Sep 2022 11:23:59 -0400 Received: from mail-qk1-x72b.google.com (mail-qk1-x72b.google.com [IPv6:2607:f8b0:4864:20::72b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08A4BBCC3D for ; Tue, 6 Sep 2022 07:35:51 -0700 (PDT) Received: by mail-qk1-x72b.google.com with SMTP id g21so8267427qka.5 for ; Tue, 06 Sep 2022 07:35:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date; bh=476rRlxJxtv02dpx4c2C/tz7co5HatpsDY03oEbQJew=; b=ZdXdqko6JBmInECYFejXaMSaYlTehHRuDJ3j05t/YVKwLUVtmBsPjWLip6RFb7O2w4 fTyUN5s0DJwVjT30WSAMEu0CcKfXxCZ0C3fuCLYBlRCzMnz7dpG8av121g3R2QCtYD+H JhuUTT9d5/I2tHqk74zqhvN7+3pdm5okBSxlQ7zV4QXkKdnFwRV6B1adVq2z8/m8N+AQ EPvzHHDHM5aKuJfK3F/NUatL6kUmKuJ8sadBq18KZ1yzAvPt4+iQotmwg3MIhJYLVkok Qw1Ca8VFDzcVvtsI/eIvVD/UsKvnuHt13i3/UZXS8bXkEiWBvW4znHJp98bZnQoFlgR8 /y+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date; bh=476rRlxJxtv02dpx4c2C/tz7co5HatpsDY03oEbQJew=; b=h7ZkP38VyiA1L300i6Uy55xLoynKhALH3KbX0cQa0tHv13ISNVqxbWynvHMvZvmwX+ XODh3GJKQuDIoy2T2PPx3j861amM3wPLen322hEjEHtowxMiLU5PgLP8PeuNr6Z2o4TQ fUJHCCJe97GsmhFtmmzvnYWUSZMYZ8x++wHhi/ExULf8330jnEeoBuwEmLeaO2R1iGNl BwMb+e6xv8GS8yJqsfWOn4U+1GhRLJ9ETTXWpuEEo3imYZsDAnBx/M8BguRmk7/nrHYR UdiqO4Sd/EjScP5CtyXJCGwemx6asFHjZ69EaZ3DQpknEtq2PqdFXcJ1YNHCmcqMqpVK fr7g== X-Gm-Message-State: ACgBeo0PmNUF3DO3RMzcUCnAenHwWVZJ89PCpaSoyQ0WLJsXpsGkfVCG 9rUYrq4GRIsxZQoC1xRQPa8= X-Google-Smtp-Source: AA6agR6bY5pRZZgZJWUTcKXx0KFpJfgIuDOfzgC6Sp5/POHeXp5qN4jI+lf5KNbNjoXHPZ5BAp/2vA== X-Received: by 2002:a05:620a:1011:b0:6bc:62fc:6e4 with SMTP id z17-20020a05620a101100b006bc62fc06e4mr36723150qkj.484.1662474937349; Tue, 06 Sep 2022 07:35:37 -0700 (PDT) Received: from localhost ([2601:4c1:c100:2270:20bc:1817:1631:6d06]) by smtp.gmail.com with ESMTPSA id br7-20020a05622a1e0700b00344f91f6fe0sm9623402qtb.67.2022.09.06.07.35.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 06 Sep 2022 07:35:36 -0700 (PDT) Date: Tue, 6 Sep 2022 07:35:36 -0700 From: Yury Norov To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Andy Shevchenko , Rasmus Villemoes , Andrew Morton , Stephen Rothwell , Thomas Gleixner , "Paul E . McKenney" , Vlastimil Babka , Dmitry Vyukov , Valentin Schneider , Sander Vanheule , Alexey Klimov , Eric Biggers Subject: Re: [PATCH v2 0/5] cpumask: cleanup nr_cpu_ids vs nr_cpumask_bits mess Message-ID: References: <20220905230820.3295223-1-yury.norov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 06, 2022 at 10:55:20AM +0200, Peter Zijlstra wrote: > On Mon, Sep 05, 2022 at 04:08:15PM -0700, Yury Norov wrote: > > cpumask subsystem uses nr_cpu_ids and nr_cpumask_bits interchangeably > > despite that the variables have different meaning and purpose. It makes > > some cpumask functions broken. > > > > This series cleans that mess and adds new config FORCE_NR_CPUS that > > allows to optimize cpumask subsystem if the number of CPUs is known > > at compile-time. > > Who will use this? Distro's can't, Raspberry PI can. Smartphone vendors can, and probably should. Ditto for vehicles and all embedded applications. > which means 99% of people will not > use this ever. Is it worth it? I will definitely enable it for myself. Actually anyone who set NR_CPUS to a non-default value, may also be interested in FORCE_NR_CPUS.