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From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	John Stultz <john.stultz@linaro.org>,
	Anton Vorontsov <anton@enomsg.org>,
	Alexey Perevalov <a.perevalov@samsung.com>,
	kyungmin.park@samsung.com, cw00.choi@samsung.com
Subject: Re: [RFC patch 2/5] hrtimer: Make use of the active bases bitfield
Date: Tue, 25 Feb 2014 13:01:49 +0100	[thread overview]
Message-ID: <20140225120149.GR9987@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20140221174639.557494772@linutronix.de>

On Fri, Feb 21, 2014 at 05:56:16PM -0000, Thomas Gleixner wrote:
> -	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
> +	while (bases) {
>  		struct hrtimer_clock_base *base;
>  		struct timerqueue_node *node;
>  		ktime_t basenow;
> +		int idx;
>  
> -		if (!(cpu_base->active_bases & (1 << i)))
> -			continue;
> +		idx = __ffs(bases);
> +		bases &= ~(1 << idx);
>  
> -		base = cpu_base->clock_base + i;
> +		base = cpu_base->clock_base + idx;
>  		basenow = ktime_add(now, base->offset);
>  
>  		while ((node = timerqueue_getnext(&base->active))) {

That's crappy for archs that end up using the generic __ffs().

The simply loop we had isn't too bad, why change this?

  reply	other threads:[~2014-02-25 12:01 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-21 17:56 [RFC patch 0/5] hrtimers: Add deferrable mode Thomas Gleixner
2014-02-21 17:56 ` [RFC patch 1/5] hrtimer: Always check for HRTIMER_MODE_REL Thomas Gleixner
2014-02-25 11:56   ` Peter Zijlstra
2014-02-21 17:56 ` [RFC patch 3/5] hrtimer: Add support for deferrable hrtimers Thomas Gleixner
2014-02-21 17:56 ` [RFC patch 2/5] hrtimer: Make use of the active bases bitfield Thomas Gleixner
2014-02-25 12:01   ` Peter Zijlstra [this message]
2014-02-21 17:56 ` [RFC patch 4/5] posix-timers: Expose deferrable mode to user space Thomas Gleixner
2014-02-21 17:56 ` [RFC patch 5/5] timerfd: " Thomas Gleixner
2014-02-25  8:36   ` Richard Cochran
2014-02-26  3:02 ` [RFC patch 0/5] hrtimers: Add deferrable mode Andy Lutomirski

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