From patchwork Mon Aug 21 06:37:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naohiro Aota X-Patchwork-Id: 13359190 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 66A1CEE49AC for ; Mon, 21 Aug 2023 06:37:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233455AbjHUGhN (ORCPT ); Mon, 21 Aug 2023 02:37:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229929AbjHUGhN (ORCPT ); Mon, 21 Aug 2023 02:37:13 -0400 Received: from esa6.hgst.iphmx.com (esa6.hgst.iphmx.com [216.71.154.45]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A1BCAB; Sun, 20 Aug 2023 23:37:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=wdc.com; i=@wdc.com; q=dns/txt; s=dkim.wdc.com; t=1692599831; x=1724135831; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=rhV3HXwgsDIqHBdHBS2K2HmQpdMw41VPG9k19oglC8M=; b=fhr6hfb5KdMPnt3awZEXRfzLc6Be6CDTBaThBOWdF3XL3/ub7pBWfzS0 gaPVloT0WpHnE0ndmkFMhOADu/Rc1PZ6lKZQmYn57kx2wdMgqGIE/rzjT OaZm0UyhFNICDlRp64kSsJ4vx2VW/sbWJZkK63xb0lG8UBPYGkXqXg2iG Et02LgLYfX97f8uDItq2ltCAfLVukpbmsJKmJvdsLDsZTUyIQzF5DPHiY OWeuuGnabWuveAb2W1kNOrsEllWPUymdQcn8bUaeORaZDvpk5SvNTnQbU bK55Jl7To1Cf92T+vLhe1Fg2yePzwVGNnZA43FkbwMoZFLKCKT160tTq8 w==; X-IronPort-AV: E=Sophos;i="6.01,189,1684771200"; d="scan'208";a="241991951" Received: from uls-op-cesaip02.wdc.com (HELO uls-op-cesaep02.wdc.com) ([199.255.45.15]) by ob1.hgst.iphmx.com with ESMTP; 21 Aug 2023 14:37:10 +0800 IronPort-SDR: kKH9Tz2kdpgPxPBrgjY+0fwRBqSWLxHS6gZqQKBRey8XRax1jgu4QyNZhrv7aAgwBcLqONP55J PdbgyRmwTQr8kWt7ts2NUfa/dOXQrh1gnR+0WbmM2PLQWCaNt7SsyrHvB6OJaVCMuXMXC4Spfo 509NrxetN6WGMWdOXm7V2dPeBNgfEY0evrR4cPyrPgsQ7rNKzYIn7UGicuGSzBqhhCcbDV8hqW kB16D0tsfOS+ALqjWiHhHdNFC3Gp+U0GSLVPEYPjgxtFfY0HYKFYnyjk9OnfTIjSWwR2XWZLyC 66A= Received: from uls-op-cesaip02.wdc.com ([10.248.3.37]) by uls-op-cesaep02.wdc.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 20 Aug 2023 22:44:42 -0700 IronPort-SDR: 3UgSJsiqSUVUIIi54+djIIlXXN5uyQZypysH+PrUV/ye7dQXFxRQZO8HyMkCNGWr4l4uXqxTUx 21T+LrOOznluzRtISlADbDoR6mIgwNw4hUkUkOrvJWiwYqRn4mpAmOj2fiA45fK5ctpURGIPd6 InQoyQkXyz3Lp34xe+sXukdHdAeel1zOXpv/8SdwGD/3R8+jDmn8gBXgzWA/moIgC2KY+276rn LYm5YYniMGSXSWb231iIFf6YE/HDIlvg6sElSRV9VIFI+RkOa5vciqZTeVwu3r5+CzdCzpcXTY WYA= WDCIronportException: Internal Received: from unknown (HELO naota-xeon.wdc.com) ([10.225.163.96]) by uls-op-cesaip02.wdc.com with ESMTP; 20 Aug 2023 23:37:11 -0700 From: Naohiro Aota To: fstests@vger.kernel.org Cc: linux-btrfs@vger.kernel.org, Naohiro Aota Subject: [PATCH v2 1/3] common/rc: introduce _random_file() helper Date: Mon, 21 Aug 2023 15:37:02 +0900 Message-ID: X-Mailer: git-send-email 2.41.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Currently, we use "ls ... | sort -R | head -n1" (or tail) to choose a random file in a directory.It sorts the files with "ls", sort it randomly and pick the first line, which wastes the "ls" sort. Also, using "sort -R | head -n1" is inefficient. For example, in a directory with 1000000 files, it takes more than 15 seconds to pick a file. $ time bash -c "ls -U | sort -R | head -n 1 >/dev/null" bash -c "ls -U | sort -R | head -n 1 >/dev/null" 15.38s user 0.14s system 99% cpu 15.536 total $ time bash -c "ls -U | shuf -n 1 >/dev/null" bash -c "ls -U | shuf -n 1 >/dev/null" 0.30s user 0.12s system 138% cpu 0.306 total So, we should just use "ls -U" and "shuf -n 1" to choose a random file. Introduce _random_file() helper to do it properly. Signed-off-by: Naohiro Aota --- common/rc | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/common/rc b/common/rc index 5c4429ed0425..2bdda30f497a 100644 --- a/common/rc +++ b/common/rc @@ -5224,6 +5224,13 @@ _soak_loop_running() { return 0 } +# Return a random file in a directory. A directory is *not* followed +# recursively. +_random_file() { + local basedir=$1 + ls -U "${basedir}" | shuf -n 1 +} + init_rc ################################################################################