From patchwork Thu Nov 26 12:20:38 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 7706371 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 505C3BF90C for ; Thu, 26 Nov 2015 12:26:46 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6A364205EA for ; Thu, 26 Nov 2015 12:26:45 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7FD0E205DF for ; Thu, 26 Nov 2015 12:26:44 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1a1vbX-0004fA-2E; Thu, 26 Nov 2015 12:24:51 +0000 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a1vbQ-0003rX-Uj for linux-arm-kernel@lists.infradead.org; Thu, 26 Nov 2015 12:24:46 +0000 Received: from pps.filterd (m0045851.ppops.net [127.0.0.1]) by mx0b-0016f401.pphosted.com (8.15.0.59/8.15.0.59) with SMTP id tAQCJidW005641; Thu, 26 Nov 2015 04:24:13 -0800 Received: from sc-exch02.marvell.com ([199.233.58.182]) by mx0b-0016f401.pphosted.com with ESMTP id 1yd3knvftc-1 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Thu, 26 Nov 2015 04:24:13 -0800 Received: from SC-EXCH04.marvell.com (10.93.176.84) by SC-EXCH02.marvell.com (10.93.176.82) with Microsoft SMTP Server (TLS) id 15.0.1044.25; Thu, 26 Nov 2015 04:24:11 -0800 Received: from maili.marvell.com (10.93.176.43) by SC-EXCH04.marvell.com (10.93.176.84) with Microsoft SMTP Server id 15.0.1044.25 via Frontend Transport; Thu, 26 Nov 2015 04:24:11 -0800 Received: from xhacker.marvell.com (unknown [10.37.135.134]) by maili.marvell.com (Postfix) with ESMTP id 49FD03F704E; Thu, 26 Nov 2015 04:24:10 -0800 (PST) From: Jisheng Zhang To: , , , , , Subject: [PATCH v2] clockevents/drivers/arm_global_timer: Use writel_relaxed in gt_compare_set Date: Thu, 26 Nov 2015 20:20:38 +0800 Message-ID: <1448540438-7028-1-git-send-email-jszhang@marvell.com> X-Mailer: git-send-email 2.6.2 MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2015-11-26_09:, , signatures=0 X-Proofpoint-Spam-Details: rule=inbound_notspam policy=inbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1507310000 definitions=main-1511260215 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151126_042445_235904_3FD798CD X-CRM114-Status: UNSURE ( 9.68 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.6 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jisheng Zhang , kernel@stlinux.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-5.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Use the relaxed version to improve performance. we measured time of 4096 rounds of gt_compare_set() spent on Marvell BG2Q: before the patch: 3690648ns on average after the patch: 1083023ns on average improved by 70%! Signed-off-by: Jisheng Zhang --- since v1: - only use relaxed io in gt_compare_set(), this function is the remaining hot code path. - Add performance numbers in commit msg. drivers/clocksource/arm_global_timer.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c index a2cb6fa..f99be6b 100644 --- a/drivers/clocksource/arm_global_timer.c +++ b/drivers/clocksource/arm_global_timer.c @@ -99,17 +99,17 @@ static void gt_compare_set(unsigned long delta, int periodic) counter += delta; ctrl = GT_CONTROL_TIMER_ENABLE; - writel(ctrl, gt_base + GT_CONTROL); - writel(lower_32_bits(counter), gt_base + GT_COMP0); - writel(upper_32_bits(counter), gt_base + GT_COMP1); + writel_relaxed(ctrl, gt_base + GT_CONTROL); + writel_relaxed(lower_32_bits(counter), gt_base + GT_COMP0); + writel_relaxed(upper_32_bits(counter), gt_base + GT_COMP1); if (periodic) { - writel(delta, gt_base + GT_AUTO_INC); + writel_relaxed(delta, gt_base + GT_AUTO_INC); ctrl |= GT_CONTROL_AUTO_INC; } ctrl |= GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE; - writel(ctrl, gt_base + GT_CONTROL); + writel_relaxed(ctrl, gt_base + GT_CONTROL); } static int gt_clockevent_shutdown(struct clock_event_device *evt)