linux-kernel - Re: printing current system time from kernel space

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Message-ID: <48D7B591.8000408@cmu.edu>
Date:	Mon, 22 Sep 2008 11:11:13 -0400
From:	George Nychis <gnychis@....edu>
To:	Sitsofe Wheeler <sitsofe@...oo.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: printing current system time from kernel space



Sitsofe Wheeler wrote:
> George Nychis wrote:
>> I spent some time googling, but could not find out how or if it is 
>> possible to read the current system time in kernel space.  I could 
>> insert a printk() somewhere in usbdev_read() then.
> 
> If that's what you want to do could you not turn on timestamps on printk 
> (CONFIG_PRINTK_TIME in the kernel hacking menu)?
> 

Thanks for the response!

You might be misunderstanding my goal.  I need a common clock between 
kernel and user space, so that I can say:

Event1 happened at time X in the kernel
Event2 happened at time X+Y in user space
The time between Event1 and Event2 was Y-X

So, turning off timestamps does not help anything here :)

What might be useful is if user space can read the current timestamp 
value that printk uses, that way I can just do a printk in the kernel 
and then read the value and print in user space.

Is this possible?

Thanks!
George
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