From: John Stultz <johnstul@us.ibm.com>
To: Roman Zippel <zippel@linux-m68k.org>
Cc: lkml <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH 1/5] split clocksource adjustment from clockosurce mult
Date: Fri, 14 Mar 2008 22:07:00 -0700 [thread overview]
Message-ID: <1205557620.6173.5.camel@jstultz-laptop> (raw)
In-Reply-To: <Pine.LNX.4.64.0803150526060.1791@scrub.home>
On Sat, 2008-03-15 at 05:28 +0100, Roman Zippel wrote:
> Hi,
>
> On Fri, 14 Mar 2008, john stultz wrote:
>
> > @@ -179,7 +181,7 @@ static inline cycle_t clocksource_read(struct clocksource *cs)
> > static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)
> > {
> > u64 ret = (u64)cycles;
> > - ret = (ret * cs->mult) >> cs->shift;
> > + ret = (ret * (cs->mult + cs->mult_adj)) >> cs->shift;
> > return ret;
> > }
>
> This add an extra memory access and extra instruction to a code path, we
> should keep as short as possible.
> I'd rather add a mult_raw or mult_org and use that for your next patch.
Yea, I played with that at first, but the functoinal duplication (two
values, both storing close to the same info) was ugly.
I guess I could go back to mult_orig.
-john
prev parent reply other threads:[~2008-03-15 5:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-15 4:04 [PATCH 0/5] time/ntp changes john stultz
2008-03-15 4:05 ` [PATCH 1/5] split clocksource adjustment from clockosurce mult john stultz
2008-03-15 4:06 ` [PATCH 2/5] introduce CLOCK_MONOTONIC_RAW john stultz
2008-03-15 4:10 ` [PATCH 3/5] cleanups ntp.c (from Ingo) john stultz
2008-03-15 4:12 ` [PATCH 4/5] ntp.c code flow clenaups " john stultz
2008-03-15 4:15 ` [PATCH 5/5] make more ntp values static john stultz
2008-03-15 5:09 ` Roman Zippel
2008-03-15 4:52 ` [PATCH 4/5] ntp.c code flow clenaups (from Ingo) Roman Zippel
2008-03-15 5:04 ` John Stultz
2008-03-15 12:39 ` Ingo Oeser
2008-03-15 17:24 ` Roman Zippel
2008-03-15 5:06 ` [PATCH 3/5] cleanups ntp.c " Roman Zippel
2008-03-15 9:32 ` Jörg-Volker Peetz
2008-03-15 17:23 ` Roman Zippel
2008-03-15 4:50 ` [PATCH 2/5] introduce CLOCK_MONOTONIC_RAW Roman Zippel
2008-03-18 2:03 ` john stultz
2008-03-18 2:27 ` john stultz
2008-03-26 3:41 ` Roman Zippel
2008-03-15 4:28 ` [PATCH 1/5] split clocksource adjustment from clockosurce mult Roman Zippel
2008-03-15 5:07 ` John Stultz [this message]
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