linux-kernel - [PATCH 61/69] clockevents/drivers/arm_global_timer: Use writel_relaxed in gt_compare

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1450448302-27429-61-git-send-email-daniel.lezcano@linaro.org>
Date:	Fri, 18 Dec 2015 15:18:14 +0100
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	tglx@...utronix.de
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	mingo@...nel.org, Jisheng Zhang <jszhang@...vell.com>,
	Srinivas Kandagatla <srinivas.kandagatla@...il.com>,
	Maxime Coquelin <maxime.coquelin@...com>,
	Patrice Chotard <patrice.chotard@...com>,
	kernel@...inux.com (open list:ARM/STI ARCHITECTURE)
Subject: [PATCH 61/69] clockevents/drivers/arm_global_timer: Use writel_relaxed in gt_compare_set

From: Jisheng Zhang <jszhang@...vell.com>

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 <jszhang@...vell.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
---
 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)
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/