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From: Thomas Gleixner <tglx@linutronix.de>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	john stultz <johnstul@us.ibm.com>,
	Richard Henderson <rth@twiddle.net>,
	lkml <linux-kernel@vger.kernel.org>,
	Matt Turner <mattst88@gmail.com>
Subject: Re: [RFC][PATCH] Convert alpha to use clocksource
Date: Mon, 22 Mar 2010 15:22:12 +0100 (CET)	[thread overview]
Message-ID: <alpine.LFD.2.00.1003221521440.3147@localhost.localdomain> (raw)
In-Reply-To: <20100322111744.GB10420@cmpxchg.org>

On Mon, 22 Mar 2010, Johannes Weiner wrote:
> > Though, even after a glance over the clocksource code, I've not
> > gotten yet to how one could estimate the "shift" value...
> > Any hints?
> 
> I had the same problem with xtensa and added a comment about what I
> did in there, maybe it helps:
> 
> 	arch/xtensa/kernel/time.c
> 
> I took the upper bound of the multiplicator (nsecs per counter unit)
> and subtracted its logarithm from my available 32 bits.  The result
> is the highest possible shift value that works for the clocksource.

clocks_calc_mult_shift() is what you are looking for.

Thanks,

	tglx

  reply	other threads:[~2010-03-22 14:22 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-18  2:01 John Stultz
2010-03-18 14:32 ` Richard Henderson
2010-03-18 17:55   ` john stultz
2010-03-18 21:40     ` Ivan Kokshaysky
2010-03-18 22:19       ` john stultz
2010-03-19 10:07         ` Ivan Kokshaysky
2010-03-19 16:47         ` Matt Turner
2010-03-19 17:13           ` Richard Henderson
2010-03-22 11:17       ` Johannes Weiner
2010-03-22 14:22         ` Thomas Gleixner [this message]
2010-03-22 16:41           ` Johannes Weiner

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