linux-kernel - [PATCH] lib/int_sqrt.c: Optimize square root function

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Message-Id: <1422538525-87669-1-git-send-email-aksgarg1989@gmail.com>
Date:	Thu, 29 Jan 2015 05:35:25 -0800
From:	Anshul Garg <aksgarg1989@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	aksgarg1989@...il.com, anshul.g@...sung.com
Subject: [PATCH] lib/int_sqrt.c: Optimize square root function

From: Anshul Garg <aksgarg1989@...il.com>

Unnecessary instructions are executing even though m is
greater than x so added logic to make m less than equal to
x before performing these operations.

Signed-off-by: Anshul Garg <aksgarg1989@...il.com>
---
 lib/int_sqrt.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index 1ef4cc3..64ae722 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -22,6 +22,9 @@ unsigned long int_sqrt(unsigned long x)
 		return x;
 
 	m = 1UL << (BITS_PER_LONG - 2);
+
+	while (m > x)
+		m >>= 2;
 	while (m != 0) {
 		b = y + m;
 		y >>= 1;
-- 
1.7.9.5


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