linux-kernel - Re: hrtimer: about hres

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] [day] [month] [year] [list]

Date:	Tue, 11 May 2010 10:33:35 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Iram Shahzad <iram.shahzad@...fujitsu.com>
cc:	linux-kernel@...r.kernel.org
Subject: Re: hrtimer: about hres_active

Iram,

please do _NOT_ top post.

On Tue, 11 May 2010, Iram Shahzad wrote:
> > No. The system switches to high resolution mode late in the boot
> > process and it does so only when there is high res capable hardware
> > available.
> 
> So far as I checked, hres_active is set to 1 in hrtimer_switch_to_hres.
> hrtimer_switch_to_hres is only called from hrtimer_run_pending.
> And hrtimer_run_pending is called from timer wheel softirq.
> That is why I concluded that hres_active is set at 1st timer softirq.
> Do you just mean that it is not the 1st softirq, or do you
> mean that in some other place in the late boot process
> there is another code which sets hres_active?

It happens from softirq context, but not from the 1st softirq.
 
> And is it correct that hres_active remains 1 forever once set to it?

Yes. There is no way back.
 
Thanks,

	tglx
--
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/