From: Thomas Gleixner <tglx@linutronix.de>
To: Iram Shahzad <iram.shahzad@jp.fujitsu.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: hrtimer: about hres_active
Date: Tue, 11 May 2010 10:33:35 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.00.1005111032200.3401@localhost.localdomain> (raw)
In-Reply-To: <D1C79E74038141C1BCD3EF70A5032E34@rainbow>
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
prev parent reply other threads:[~2010-05-11 8:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-06 6:03 [PATCH 0/2] ftrace: updates for powerpc Steven Rostedt
2009-02-06 6:03 ` [PATCH 1/2] ftrace, powerpc: replace debug macro with proper pr_deug Steven Rostedt
2009-02-06 6:07 ` Steven Rostedt
2009-02-06 7:05 ` Benjamin Herrenschmidt
2009-02-06 13:29 ` Steven Rostedt
2009-02-06 6:03 ` [PATCH 2/2] powerpc, ftrace: fix compile error when modules not configured Steven Rostedt
2009-02-06 6:07 ` Steven Rostedt
2009-02-06 6:23 ` Michael Neuling
2009-02-06 7:04 ` [PATCH 0/2] ftrace: updates for powerpc Benjamin Herrenschmidt
2009-02-06 13:28 ` Steven Rostedt
2010-05-10 10:27 ` hrtimer: about hres_active Iram Shahzad
2010-05-10 15:12 ` Thomas Gleixner
2010-05-11 1:39 ` Iram Shahzad
2010-05-11 8:33 ` Thomas Gleixner [this message]
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