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 17:06:33 +0000
From:	Shuah Khan <shuah.kh@...sung.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	"len.brown@...el.com" <len.brown@...el.com>,
	"pavel@....cz" <pavel@....cz>, "rjw@...k.pl" <rjw@...k.pl>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"paul.gortmaker@...driver.com" <paul.gortmaker@...driver.com>,
	"joe@...ches.com" <joe@...ches.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"shuahkhan@...il.com" <shuahkhan@...il.com>,
	Shuah Khan <shuah.kh@...sung.com>
Subject: Re: [PATCH v2] power: new trace event to print device suspend and
 resume time

On 07/17/2013 10:35 AM, Steven Rostedt wrote:
> On Wed, 2013-07-17 at 09:57 -0600, Shuah Khan wrote:
>
>> +TRACE_EVENT(device_pm_report_time,
>> +
>> +	TP_PROTO(const char *device, const char *driver, const char *parent,
>> +		 const char *pm_ops, ktime_t ops_time, char *pm_event_str,
>> +		 int error),
>> +
>> +	TP_ARGS(device, driver, parent, pm_ops, ops_time, pm_event_str, error),
>> +
>> +	TP_STRUCT__entry(
>> +		__string(device, device)
>> +		__string(driver, driver)
>> +		__string(parent, parent)
>> +		__string(pm_ops, pm_ops)
>> +		__string(pm_event_str, pm_event_str)
>> +		__field(s64, ops_time)
>> +		__field(int, error)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__assign_str(device, device);
>> +		__assign_str(driver, driver);
>> +		__assign_str(parent, parent);
>> +		__assign_str(pm_ops, pm_ops);
>> +		__assign_str(pm_event_str, pm_event_str);
>> +		__entry->ops_time = ktime_to_ns(ops_time) >> 10;
>
> You may want to just record the ops_time, and do the conversion in the
> TP_printk(). This is the fast path, and any calculations done here just
> increases the overhead of the trace point.
>
> -- Steve

Thanks for the review and pointing the overhead out. Will fix that.

-- Shuah

-- 
Shuah Khan, Linux Kernel Developer - Open Source Group Samsung Research 
America (Silicon Valley) shuah.kh@...sung.com | (970) 672-0658
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