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 X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4BC15C282D4 for ; Wed, 30 Jan 2019 05:55:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1907420863 for ; Wed, 30 Jan 2019 05:55:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="H9v+LN8M" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726331AbfA3FzG (ORCPT ); Wed, 30 Jan 2019 00:55:06 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:36463 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725791AbfA3FzG (ORCPT ); Wed, 30 Jan 2019 00:55:06 -0500 Received: by mail-wm1-f68.google.com with SMTP id p6so20178379wmc.1 for ; Tue, 29 Jan 2019 21:55:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=bxG1jsbCAvDb2G+7mh+61CiKZy1Hkeq0wdB2KS1FVYs=; b=H9v+LN8MHHeOYdhO+cqenNlJUlzi/DzhWqGMdU4WlDZdLkgV4mLgQOP0OFI0mEyVtn NeBESs1OnMl0D/M89kwhCKtTNPLwZvTBYgk06L1Q46Dl0AnNanIUT004A9e8g2ab9pxK 6EGCYNw4cyCqfgofAXaxEF1/2m69v2X6tMZ+V0vmXLftcAA/rtaUIHDJwqwgzuSyNlWR a9hW1JaFbiAXO7cPBW0rmvpRije6AEilphmH5N7ZmjXNT1z/xkz5yaqCcbzaIf924cAS BJ0Z0Cjadna0QPctbp18vcxvdYzaPTKuCkaC9HB1yBQ8MxcFTjPcCVNFTjEf8qQ/SYKX dwTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=bxG1jsbCAvDb2G+7mh+61CiKZy1Hkeq0wdB2KS1FVYs=; b=L2jCXAxAkEx9VphnHMPbUVwD+GyfGHJb8N2GdpXiscb7Y9hq4GxAHXtVT5EUGCILbm CSjf42a4+6L8vgrAR+TurYaX7ccbI8rZMP1fYnkc4PceKn/qwRN2iTQgB/ydT8rzlrdV ZS3IHYLczPtUZs25hh9zzqT1ljlT5hM3DRp3GLz7OrlozHGYTFLh/6CgaAeoI0XZPlLy FdSrmMgqQgrWgySFTzccpU0+hQvJo/7nCIO010nHOtyNIsXU4ZNqi1bQ1lL6+qMP0L8e CcQpsFYDDlGFxu/5N0WiXjm3vebwcC/B99eiK1o79KdCXYuVRfgT67CSwqgD8xmkaeHb Yy1g== X-Gm-Message-State: AJcUukfALTSNjbM08w8mnyptOnlTmzUo2S1WCeBcBMoU9RP4q6Fyl7Ac ZSlByAGN/ft4OvGXnAMS9xBvn+g= X-Google-Smtp-Source: ALg8bN5yRm0+RDVFy0H2VnEta6POR9+70xZpYP7Asxo9WoN3LTGJau/X9cr5Qw4LKRZlpUUO6WTK/g== X-Received: by 2002:a1c:2e43:: with SMTP id u64mr24333705wmu.52.1548827704410; Tue, 29 Jan 2019 21:55:04 -0800 (PST) Received: from avx2 ([46.53.246.247]) by smtp.gmail.com with ESMTPSA id c14sm516353wme.13.2019.01.29.21.55.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 29 Jan 2019 21:55:03 -0800 (PST) Date: Wed, 30 Jan 2019 08:55:01 +0300 From: Alexey Dobriyan To: Andrew Morton Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] proc: calculate end pointer for /proc/*/* lookup at compile time Message-ID: <20190130055501.GA2115@avx2> References: <20190114200422.GB9680@avx2> <20190129141848.5f3d2d1aa125c8ec45ee091d@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190129141848.5f3d2d1aa125c8ec45ee091d@linux-foundation.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 29, 2019 at 02:18:48PM -0800, Andrew Morton wrote: > On Mon, 14 Jan 2019 23:04:23 +0300 Alexey Dobriyan wrote: > > > Compilers like to transform loops like > > > > for (i = 0; i < n; i++) { > > [use p[i]] > > } > > > > into > > for (p = p0; p < end; p++) { > > ... > > } > > > > Do it by hand, so that it results in overall simpler loop > > and smaller code. > > > > Space savings: > > > > $ ./scripts/bloat-o-meter ../vmlinux-001 ../obj/vmlinux > > add/remove: 0/0 grow/shrink: 2/1 up/down: 4/-9 (-5) > > Function old new delta > > proc_tid_base_lookup 17 19 +2 > > proc_tgid_base_lookup 17 19 +2 > > proc_pident_lookup 179 170 -9 > > > > Note: this trick bloats readdir, so don't do it :-\ > > I don't understand the Note:. Can you please expand? The same could be done to proc_pident_readdir(), but the code becomes bigger for some reason.