From: Joe Perches <joe@perches.com>
To: Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Anshul Garg <aksgarg1989@gmail.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"anshul.g@samsung.com" <anshul.g@samsung.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH] lib/int_sqrt.c: Optimize square root function
Date: Fri, 21 Jul 2017 05:15:10 -0700 [thread overview]
Message-ID: <1500639310.14415.25.camel@perches.com> (raw)
In-Reply-To: <20170721114039.dqip5wj2tha42mol@hirez.programming.kicks-ass.net>
On Fri, 2017-07-21 at 13:40 +0200, Peter Zijlstra wrote:
> @@ -21,7 +22,11 @@ unsigned long int_sqrt(unsigned long x)
> if (x <= 1)
> return x;
>
> - m = 1UL << (BITS_PER_LONG - 2);
> + m = 1UL << (__fls(x) & ~1U);
> +
> + while (m > x)
> + m >>= 2;
while (m > x) ?
Belt and suspenders if __fls is broken?
next prev parent reply other threads:[~2017-07-21 12:15 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-02 17:12 [PATCH] lib/int_sqrt.c: Optimize square root function Anshul Garg
2015-02-02 19:00 ` Linus Torvalds
2015-02-02 19:13 ` Linus Torvalds
2015-02-03 4:41 ` Davidlohr Bueso
2015-02-03 4:57 ` Davidlohr Bueso
2015-02-03 15:54 ` Anshul Garg
2017-07-20 11:24 ` Peter Zijlstra
2017-07-20 11:52 ` Joe Perches
2017-07-20 14:13 ` Peter Zijlstra
2017-07-20 15:27 ` Peter Zijlstra
2017-07-20 18:31 ` Linus Torvalds
2017-07-20 22:34 ` Peter Zijlstra
2017-07-20 23:24 ` Linus Torvalds
2017-07-21 11:40 ` Peter Zijlstra
2017-07-21 12:15 ` Joe Perches [this message]
2017-07-21 13:26 ` Peter Zijlstra
2017-07-21 13:33 ` Peter Zijlstra
2015-02-03 4:47 ` Davidlohr Bueso
2015-02-03 15:42 ` Anshul Garg
2015-02-05 18:20 ` Linus Torvalds
2015-02-05 18:33 ` Linus Torvalds
2015-02-05 18:43 ` Anshul Garg
2015-02-05 19:37 ` Linus Torvalds
2015-02-08 15:39 ` Anshul Garg
2015-02-02 19:10 ` Joe Perches
2015-02-02 19:39 ` Linus Torvalds
-- strict thread matches above, loose matches on Subject: below --
2015-01-29 13:35 Anshul Garg
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