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From: john stultz <johnstul@us.ibm.com>
To: Roman Zippel <zippel@linux-m68k.org>
Cc: lkml <linux-kernel@vger.kernel.org>,
	yoshfuji@linux-ipv6.org,
	Ulrich Windl <ulrich.windl@rz.uni-regensburg.de>,
	George Anzinger <george@mvista.com>,
	joe-lkml@rameria.de
Subject: Re: [RFC][PATCH] NTP shift_right cleanup (v. A1)
Date: Wed, 14 Sep 2005 11:25:03 -0700	[thread overview]
Message-ID: <1126722303.3455.61.camel@cog.beaverton.ibm.com> (raw)
In-Reply-To: <Pine.LNX.4.61.0509142010030.3728@scrub.home>

On Wed, 2005-09-14 at 20:13 +0200, Roman Zippel wrote:
> > @@ -792,13 +769,8 @@ static void update_wall_time_one_tick(vo
> >  	 * advance the tick more.
> >  	 */
> >  	time_phase += time_adj;
> > -	if (time_phase <= -FINENSEC) {
> > -		long ltemp = -time_phase >> (SHIFT_SCALE - 10);
> > -		time_phase += ltemp << (SHIFT_SCALE - 10);
> > -		delta_nsec -= ltemp;
> > -	}
> > -	else if (time_phase >= FINENSEC) {
> > -		long ltemp = time_phase >> (SHIFT_SCALE - 10);
> > +	if (abs(time_phase) >= FINENSEC) {
> > +		long ltemp = shift_right(time_phase, (SHIFT_SCALE - 10));
> >  		time_phase -= ltemp << (SHIFT_SCALE - 10);
> >  		delta_nsec += ltemp;
> >  	}
> 
> I checked and this actually generates worse code.

Well, if I drop the abs() and use:
	if ((time_phase >= FINENSEC) || (time_phase <= -FINENSEC))

It looks pretty close in my test. Is that cool with you?

thanks
-john



  reply	other threads:[~2005-09-14 18:26 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-14 17:48 john stultz
2005-09-14 17:53 ` john stultz
2005-09-14 18:39   ` NTP leap second question George Anzinger
2005-09-14 18:54     ` john stultz
2005-09-15  6:49       ` Ulrich Windl
2005-09-15 17:21         ` Kyle Moffett
2005-09-15 18:35           ` Alan Cox
2005-09-14 18:13 ` [RFC][PATCH] NTP shift_right cleanup (v. A1) Roman Zippel
2005-09-14 18:25   ` john stultz [this message]
2005-09-14 19:11     ` Roman Zippel
2005-09-14 18:40 ` [RFC][PATCH] NTP shift_right cleanup (v. A2) john stultz
2005-09-20  1:28 ` [PATCH] " john stultz
2005-09-21  3:24   ` [PATCH] NTP shift_right cleanup (v. A3) john stultz
2005-09-21  5:24     ` Nick Piggin
2005-09-21  8:13       ` Ulrich Windl
2005-09-21 12:18         ` Nick Piggin

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