linux-kernel - Re: [PATCH v2] power: new trace event to print device suspend and resume time

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Date:	Wed, 17 Jul 2013 09:08:45 -0700
From:	Joe Perches <joe@...ches.com>
To:	Shuah Khan <shuah.kh@...sung.com>
Cc:	len.brown@...el.com, pavel@....cz, rjw@...k.pl,
	gregkh@...uxfoundation.org, rostedt@...dmis.org,
	fweisbec@...il.com, mingo@...hat.com, paul.gortmaker@...driver.com,
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	shuahkhan@...il.com
Subject: Re: [PATCH v2] power: new trace event to print device suspend and
 resume time

On Wed, 2013-07-17 at 09:57 -0600, Shuah Khan wrote:
> A new trace event is added to pm events to print time it takes to suspend and
> resume a device. It generates trace message that includes device, driver,
> parent information in addition to the type of pm ops invoked as well as the
> pm event and error status from the pm ops. Example trace below:
> 
> bash-2484  [001] ....   907.330148: device_pm_report_time: backlight acpi_video0 parent=0000:00:02.0 state=freeze ops=class  usecs=0 err=0
> 
> bash-2484  [001] ....   909.906743: device_pm_report_time: backlight acpi_video0 parent=0000:00:02.0 state=restore ops=class  usecs=0 err=0

Hi again Shuah.

A few things:

> diff --git a/include/trace/events/power.h b/include/trace/events/power.h
[]
> +	TP_printk("%s %s parent=%s state=%s ops=%s usecs=%lld err=%d\n",

As I wrote before, do not end a TP_printk with "\n",

All TP_printks are self-contained and are not possible
to use a thing like pr_cont so no newline is ever used.

Use:

	TP_printk("%s %s parent=%s state=%s ops=%s usecs=%lld err=%d",

Given the data is in nsecs, why use usecs for the time?
I think full resolution would be better.

Why are there two spaces after "ops=class"? One would be more normal.

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