linux-kernel - Re: [PATCH 1/9] time: Condense timekeeper.xtime into xtime

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Date:	Fri, 2 Mar 2012 15:13:25 -0600 (CST)
From:	Christoph Lameter <cl@...ux.com>
To:	John Stultz <john.stultz@...aro.org>
cc:	lkml <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Richard Cochran <richardcochran@...il.com>
Subject: Re: [PATCH 1/9] time: Condense timekeeper.xtime into xtime_sec

On Thu, 1 Mar 2012, John Stultz wrote:

> +static inline void tk_normalize_xtime(struct timekeeper *tk)
> +{
> +	while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
> +		tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
> +		tk->xtime_sec++;
> +	}
> +}

Could we avoid the loop?

y = ((u64)NSEC_PER_SEC << tk->shift));
tk->xtime_sec += tk->xtime_nsec / y;
tk->xtime_nsec %= y;

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