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From: john stultz <johnstul@us.ibm.com>
To: george anzinger <george@mvista.com>
Cc: Andrew Morton <akpm@digeo.com>,
	lkml <linux-kernel@vger.kernel.org>,
	James.Bottomley@SteelEye.com, shemminger@osdl.org, alex@ssi.bg
Subject: Re: [PATCH] linux-2.5.67_lost-tick-fix_A2
Date: 16 Apr 2003 16:21:36 -0700	[thread overview]
Message-ID: <1050535296.1077.204.camel@w-jstultz2.beaverton.ibm.com> (raw)
In-Reply-To: <3E9DE126.7040001@mvista.com>

On Wed, 2003-04-16 at 16:03, george anzinger wrote:
> john stultz wrote: 
> > Some of the divs and mods being added here might concern folks, but by
> > not calling timer->get_offset() in detect_lost_tick() we eliminate much
> > of the same math. I did some simple cycle counting and the new code
> > comes out on average equivalent or faster. 
> 
> I think that if you look at the generated code you may find that there 
> are NO div in the asm code.  The C folks know about scaling to avoid 
> div especially when the divisor is a constant :)

Indeed you are correct. An objdump of both the timer_tsc.o and
timer_cyclone.o code reveals that the only divs occur in init code. I
like your argument better then mine :)

thanks
-john





      reply	other threads:[~2003-04-16 23:12 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-04-16 22:02 [PATCH] linux-2.5.67_lost-tick-fix_A2 john stultz
2003-04-16 22:32 ` Andrew Morton
2003-04-16 22:46   ` john stultz
2003-04-16 23:02     ` Andrew Morton
2003-04-16 23:03 ` george anzinger
2003-04-16 23:21   ` john stultz [this message]

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