linux-kernel - Re: [linux-pm] [PATCH v4] PM: add statistics debugfs file for suspend to ram

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Date:	Wed, 10 Aug 2011 12:58:54 -0700
From:	Greg KH <gregkh@...e.de>
To:	"Mansoor, Illyas" <illyas.mansoor@...el.com>
Cc:	"Liu, ShuoX" <shuox.liu@...el.com>,
	"linux-pm@...ts.linux-foundation.org" 
	<linux-pm@...ts.linux-foundation.org>,
	"Brown, Len" <len.brown@...el.com>,
	"Yanmin_zhang@...ux.intel.com" <Yanmin_zhang@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [linux-pm] [PATCH v4] PM: add statistics debugfs file for
 suspend	to ram

On Thu, Aug 11, 2011 at 01:22:56AM +0530, Mansoor, Illyas wrote:
> static pm_message_t pm_transition;
> > > >
> > > > @@ -464,8 +465,12 @@ void dpm_resume_noirq(pm_message_t state)
> > > >  		mutex_unlock(&dpm_list_mtx);
> > > >
> > > >  		error = device_resume_noirq(dev, state);
> > > > -		if (error)
> > > > +		if (error) {
> > > > +			suspend_stats.failed_resume_noirq++;
> > > > +			dpm_save_failed_step(SUSPEND_RESUME_NOIRQ);
> > > > +			dpm_save_failed_dev(dev_name(dev));
> > >
> > > Please make these statistics conditionally enabled, so on a production system
> > > If we need to disable these statistics code we should be able to do so.
> > 
> > Why, are they taking time or space that is needed for something else?
> > What's the downside here of just not always having this enabled?
> 
> Why have something that is not required/Used?

Because someone might need it and rebuilding a kernel isn't possible on
lots of devices.

> Its only useful if DEBUGFS is configured anyways

Almost all systems these days have debugfs enabled, so that's a moot
point.

greg k-h
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