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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8E5CACF58C6 for ; Wed, 19 Nov 2025 18:24:32 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vLmqp-0000y3-4L; Wed, 19 Nov 2025 13:24:19 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vLlyf-0002S5-5f for qemu-devel@nongnu.org; Wed, 19 Nov 2025 12:28:22 -0500 Received: from mail-il1-x12f.google.com ([2607:f8b0:4864:20::12f]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1vLlyd-0004JT-Mq for qemu-devel@nongnu.org; Wed, 19 Nov 2025 12:28:20 -0500 Received: by mail-il1-x12f.google.com with SMTP id e9e14a558f8ab-4332381ba9bso101695ab.1 for ; Wed, 19 Nov 2025 09:28:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1763573298; x=1764178098; darn=nongnu.org; h=cc:to:subject:message-id:date:mime-version:from:from:to:cc:subject :date:message-id:reply-to; bh=gtPbqc+AMCqouNpafbfHY6FEx0CZ0+IPs9jgeWbmnW0=; b=i2sgw+kLyd1FtZVYwJU9Di2Gsc/KQp0OiQsNJtIWIRisPvClNt807s8f9EdxU5dIdz LmbVrpGOw241MXaAjR6IpyeBkrgzhHupxaQludDk3OdCDQw9sPz7qOrtLGQLPPo8lMi1 qlicREOAkyCFqHR3wfA50vp4zmtMMLvbY7P6iPtPZbyasa3Y0ZwHwScBqJmdKOqHi7Ey nsL8hcmgRy1fkkv+8b5+oIUxNFOdji0+ekqwkRFp/hvWaRee6DpBhwYOtvA1zGry1GAJ a/pp7lyY2oh2B7coB9Aoyomq2eSiKqXKdTjWYo+ifU8AdXdPu3mVmerVlkb0l3tCTswE 0/bA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763573298; x=1764178098; h=cc:to:subject:message-id:date:mime-version:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=gtPbqc+AMCqouNpafbfHY6FEx0CZ0+IPs9jgeWbmnW0=; b=BuskUgC0uYHhhCrgLVjJq3K/klmVi1f7e7Gh66EdsAG9IFhCv1e5jN+xLBp7uLj7lR pNx6wqFJHZcMGLvUu4/aX6uYqWzSlJqbZkNnutTK0p2jr0ETQP/72WJerzW/6PT12P9J bj+UtBCzP5dxzd1eh85KzhNpn6B9lB2verGvSHhs1DsWUHeclISBR84/gXV50KO+KhUf XYhM9ZtbwwwC6d12lSUA9xtwJgSChg2IT/JAAUX94ysW2yWu08EZJ2BFHglpL9bnTa/5 Wh7XcCLtAOnNF/3dhA29yMTFMw+1nWB490yJ2pbUOweWluj0qXmNt0EoF82WvGEYUYqS zGaA== X-Gm-Message-State: AOJu0YwoBqUVUIAwtT4ywK0WtUB9Cnj4acjf+a1I0ylKiBsy9cPgLXnf Nfji3cdmQeFQ4EXQusPzNyccDNPibaWq0bHvyIwQ+YSh8s/I3kPwAAW8KkEfQXDmEGseMvTdInF c85nuO9+/DD+QPT4NuUIuLIo5YWZtv65/P42o X-Gm-Gg: ASbGncs+tc/m97PC4oiAiQat/dbNmmf2W23eMUZnnymbNLo12AEVlJpd38msvXLsh9D VrCEuCT1qlzoQM73dO9dUf2UTbq4oP6IMj2TKGpHiq0UNqVJONFrPKTL0ulykcjWnCHBnQ2jYuP ZZjfP2SS/ENPjwJ59EwyT50Oj3yHufTGRN7doIYs4eGAurV8FK7tm4N6eDsoZg3ZnCi6b16j0BS URGDHSl3JZM5tUt9gy/eErcj4MWl5JHKSjk2N8ay5ZfvqiLAUX0timfQ68u4cFAcLD1w/kQS3FB fYQPKQ== X-Google-Smtp-Source: AGHT+IGseESW3+TiyVtUnh2rZyg+uK4cev1+1hkrm4TZ4XrmLI6ulCRgJHyF+Y1pce/ktftxg4muswV4qK6Ggaa1raY= X-Received: by 2002:a05:6e02:1fc1:b0:433:80d9:708a with SMTP id e9e14a558f8ab-435a90397f9mr2949175ab.17.1763573297778; Wed, 19 Nov 2025 09:28:17 -0800 (PST) Received: from 753933720722 named unknown by gmailapi.google.com with HTTPREST; Wed, 19 Nov 2025 12:28:16 -0500 Received: from 753933720722 named unknown by gmailapi.google.com with HTTPREST; Wed, 19 Nov 2025 12:28:16 -0500 From: konrad.schwarz@gmail.com X-Mailer: git-send-email 2.39.5 MIME-Version: 1.0 Date: Wed, 19 Nov 2025 12:28:16 -0500 X-Gm-Features: AWmQ_bmxDrPqQHqirOr4JNKV_MvO3XAJ0Poygr60YQE1UpKWXZL8xMrGgdNAAQg Message-ID: Subject: [PATCH 1/1] scripts: Changed potential O(n) file size calculation to O(1) To: qemu-devel@nongnu.org Cc: philmd@linaro.org, Konrad Schwarz , jan.kiszka@siemens.com Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::12f; envelope-from=konrad.schwarz@gmail.com; helo=mail-il1-x12f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-Mailman-Approved-At: Wed, 19 Nov 2025 13:24:16 -0500 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The mkemmc.sh script calculates file sizes via `wc -c'. `wc' normally works by reading the entire file, resulting in O(n) performance. Unix file systems obviously know a file's size and POSIX `ls' reports this information unambiguously, so replacing `wc' with `ls' ensures O(1) performance. The files in question tend to be large making this change worthwhile. Signed-off-by: Konrad Schwarz --- scripts/mkemmc.sh | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/scripts/mkemmc.sh b/scripts/mkemmc.sh index 45dc3f08fa..d2c4e84b16 100755 --- a/scripts/mkemmc.sh +++ b/scripts/mkemmc.sh @@ -37,13 +37,19 @@ usage() { exit "$1" } +file_size() { + ls_line=$(ls -Hdog "$1") || return + printf %s\\n "$ls_line" | cut -d\ -f3 + unset ls_line +} + process_size() { name=$1 image_file=$2 alignment=$3 image_arg=$4 if [ "${image_arg#*:}" = "$image_arg" ]; then - if ! size=$(wc -c < "$image_file" 2>/dev/null); then + if ! size=$(file_size "$image_file"); then echo "Missing $name image '$image_file'." >&2 exit 1 fi @@ -105,7 +111,7 @@ check_truncation() { if [ "$image_file" = "/dev/zero" ]; then return fi - if ! actual_size=$(wc -c < "$image_file" 2>/dev/null); then + if ! actual_size=$(file_size "$image_file"); then echo "Missing image '$image_file'." >&2 exit 1 fi -- 2.39.5