linux-kernel - Re: [RFC patch 2/5] hrtimer: Make use of the active bases bitfield

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 25 Feb 2014 13:01:49 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	John Stultz <john.stultz@...aro.org>,
	Anton Vorontsov <anton@...msg.org>,
	Alexey Perevalov <a.perevalov@...sung.com>,
	kyungmin.park@...sung.com, cw00.choi@...sung.com
Subject: Re: [RFC patch 2/5] hrtimer: Make use of the active bases bitfield

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?
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/