From patchwork Wed Nov 25 16:01:53 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 7700831 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 6BB6A9F2EC for ; Wed, 25 Nov 2015 16:08:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 95B022084C for ; Wed, 25 Nov 2015 16:08:19 +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 A9CF220848 for ; Wed, 25 Nov 2015 16:08:18 +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 1a1caC-0000zW-U5; Wed, 25 Nov 2015 16:06:12 +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 1a1cZp-0000mR-D7 for linux-arm-kernel@lists.infradead.org; Wed, 25 Nov 2015 16:05:50 +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 tAPG55ol014483; Wed, 25 Nov 2015 08:05:24 -0800 Received: from sc-exch04.marvell.com ([199.233.58.184]) by mx0b-0016f401.pphosted.com with ESMTP id 1yd3knsvww-1 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT); Wed, 25 Nov 2015 08:05:24 -0800 Received: from SC-EXCH04.marvell.com (10.93.176.84) by SC-EXCH04.marvell.com (10.93.176.84) with Microsoft SMTP Server (TLS) id 15.0.1044.25; Wed, 25 Nov 2015 08:05:22 -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; Wed, 25 Nov 2015 08:05:22 -0800 Received: from xhacker.marvell.com (unknown [10.37.135.134]) by maili.marvell.com (Postfix) with ESMTP id D7B213F7040; Wed, 25 Nov 2015 08:05:21 -0800 (PST) From: Jisheng Zhang To: , , Subject: [PATCH v4 2/2] clocksource/drivers/dw_apb_timer: Use {readl|writel}_relaxed in critical path Date: Thu, 26 Nov 2015 00:01:53 +0800 Message-ID: <1448467313-5626-3-git-send-email-jszhang@marvell.com> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1448467313-5626-1-git-send-email-jszhang@marvell.com> References: <1448467313-5626-1-git-send-email-jszhang@marvell.com> MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2015-11-25_11:, , 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-1511250281 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151125_080549_666672_68B8DBA2 X-CRM114-Status: GOOD ( 12.69 ) 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 , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.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=-4.8 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable 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 It's safe to use the relaxed version. From another side, the relaxed io accessor macros are available on all architectures now, so we can use the relaxed versions to get a trivial system performance improvement, we measured time the following functions spent on Marvell BG4CT: 4096 rounds of __apbt_read_clocksource() call: before the patch: 1263240ns on average after the patch: 1250080ns on average improved by 1% 4096 rounds of apbt_eoi() call: before the patch: 1290960ns on average after the patch: 1248240ns on average 4096 rounds of apbt_next_event() call: before the patch: 3333660ns on average after the patch: 1322040ns on average improved by 60%! Signed-off-by: Jisheng Zhang --- drivers/clocksource/dw_apb_timer.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c index 114696b..6334526 100644 --- a/drivers/clocksource/dw_apb_timer.c +++ b/drivers/clocksource/dw_apb_timer.c @@ -60,6 +60,17 @@ static inline void apbt_writel(struct dw_apb_timer *timer, u32 val, writel(val, timer->base + offs); } +static inline u32 apbt_readl_relaxed(struct dw_apb_timer *timer, unsigned long offs) +{ + return readl_relaxed(timer->base + offs); +} + +static inline void apbt_writel_relaxed(struct dw_apb_timer *timer, u32 val, + unsigned long offs) +{ + writel_relaxed(val, timer->base + offs); +} + static void apbt_disable_int(struct dw_apb_timer *timer) { u32 ctrl = apbt_readl(timer, APBTMR_N_CONTROL); @@ -81,7 +92,7 @@ void dw_apb_clockevent_pause(struct dw_apb_clock_event_device *dw_ced) static void apbt_eoi(struct dw_apb_timer *timer) { - apbt_readl(timer, APBTMR_N_EOI); + apbt_readl_relaxed(timer, APBTMR_N_EOI); } static irqreturn_t dw_apb_clockevent_irq(int irq, void *data) @@ -200,13 +211,13 @@ static int apbt_next_event(unsigned long delta, struct dw_apb_clock_event_device *dw_ced = ced_to_dw_apb_ced(evt); /* Disable timer */ - ctrl = apbt_readl(&dw_ced->timer, APBTMR_N_CONTROL); + ctrl = apbt_readl_relaxed(&dw_ced->timer, APBTMR_N_CONTROL); ctrl &= ~APBTMR_CONTROL_ENABLE; - apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + apbt_writel_relaxed(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); /* write new count */ - apbt_writel(&dw_ced->timer, delta, APBTMR_N_LOAD_COUNT); + apbt_writel_relaxed(&dw_ced->timer, delta, APBTMR_N_LOAD_COUNT); ctrl |= APBTMR_CONTROL_ENABLE; - apbt_writel(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); + apbt_writel_relaxed(&dw_ced->timer, ctrl, APBTMR_N_CONTROL); return 0; } @@ -342,7 +353,8 @@ static cycle_t __apbt_read_clocksource(struct clocksource *cs) struct dw_apb_clocksource *dw_cs = clocksource_to_dw_apb_clocksource(cs); - current_count = apbt_readl(&dw_cs->timer, APBTMR_N_CURRENT_VALUE); + current_count = apbt_readl_relaxed(&dw_cs->timer, + APBTMR_N_CURRENT_VALUE); return (cycle_t)~current_count; }