From patchwork Mon May 20 12:50:57 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Simmons X-Patchwork-Id: 10951049 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5F9B7112C for ; Mon, 20 May 2019 12:52:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4EDF7285B5 for ; Mon, 20 May 2019 12:52:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 436C128735; Mon, 20 May 2019 12:52:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from pdx1-mailman02.dreamhost.com (pdx1-mailman02.dreamhost.com [64.90.62.194]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id EE9D0285B5 for ; Mon, 20 May 2019 12:52:32 +0000 (UTC) Received: from pdx1-mailman02.dreamhost.com (localhost [IPv6:::1]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id BBA1D21FA84; Mon, 20 May 2019 05:51:56 -0700 (PDT) X-Original-To: lustre-devel@lists.lustre.org Delivered-To: lustre-devel-lustre.org@pdx1-mailman02.dreamhost.com Received: from smtp4.ccs.ornl.gov (smtp4.ccs.ornl.gov [160.91.203.40]) by pdx1-mailman02.dreamhost.com (Postfix) with ESMTP id 0F55121F1D8 for ; Mon, 20 May 2019 05:51:20 -0700 (PDT) Received: from star.ccs.ornl.gov (star.ccs.ornl.gov [160.91.202.134]) by smtp4.ccs.ornl.gov (Postfix) with ESMTP id 73DCB100519C; Mon, 20 May 2019 08:51:13 -0400 (EDT) Received: by star.ccs.ornl.gov (Postfix, from userid 2004) id 70B402BC; Mon, 20 May 2019 08:51:13 -0400 (EDT) From: James Simmons To: Andreas Dilger , Oleg Drokin , NeilBrown Date: Mon, 20 May 2019 08:50:57 -0400 Message-Id: <1558356671-29599-16-git-send-email-jsimmons@infradead.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1558356671-29599-1-git-send-email-jsimmons@infradead.org> References: <1558356671-29599-1-git-send-email-jsimmons@infradead.org> Subject: [lustre-devel] [PATCH v2 15/29] lustre: lprocfs: use log2.h macros instead of shift loop. X-BeenThere: lustre-devel@lists.lustre.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "For discussing Lustre software development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lustre Development List MIME-Version: 1.0 Errors-To: lustre-devel-bounces@lists.lustre.org Sender: "lustre-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: NeilBrown These shift loops seem to be trying to avoid doing a multiplication. The same effect can be achieved more transparently using rounddown_pow_of_two(). Even though there is a multiplication in the C code, the resulting machine code just does a single shift. As rounddown_pow_of_two() is not defined for 0, and as we cannot be positively use the blk_size is non-zero, use blk_size ?: 1. Signed-off-by: NeilBrown --- fs/lustre/obdclass/lprocfs_status.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/fs/lustre/obdclass/lprocfs_status.c b/fs/lustre/obdclass/lprocfs_status.c index 29c6b5d..2af9dad 100644 --- a/fs/lustre/obdclass/lprocfs_status.c +++ b/fs/lustre/obdclass/lprocfs_status.c @@ -374,9 +374,7 @@ static ssize_t kbytestotal_show(struct kobject *kobj, struct attribute *attr, u32 blk_size = osfs.os_bsize >> 10; u64 result = osfs.os_blocks; - while (blk_size >>= 1) - result <<= 1; - + result *= rounddown_pow_of_two(blk_size ?: 1); return sprintf(buf, "%llu\n", result); } @@ -397,8 +395,7 @@ static ssize_t kbytesfree_show(struct kobject *kobj, struct attribute *attr, u32 blk_size = osfs.os_bsize >> 10; u64 result = osfs.os_bfree; - while (blk_size >>= 1) - result <<= 1; + result *= rounddown_pow_of_two(blk_size ?: 1); return sprintf(buf, "%llu\n", result); } @@ -420,8 +417,7 @@ static ssize_t kbytesavail_show(struct kobject *kobj, struct attribute *attr, u32 blk_size = osfs.os_bsize >> 10; u64 result = osfs.os_bavail; - while (blk_size >>= 1) - result <<= 1; + result *= rounddown_pow_of_two(blk_size ?: 1); return sprintf(buf, "%llu\n", result); }