On 6/28/06, Fernando Apesteguía <fernando.apesteguia@xxxxxxxxx> wrote:
Hi,
I would like to take some time measurements for some functions from my
kernel module. In a first attempt, I tried to use current_kernel_time, but
this often returns the same value before and after the call I want to
measure (even, when I use the tv_nsec field.).
ts1=current_kernel_time;
function();
ts2=current_kernel_time;
So now I'm using rdtscll instead of current_kernel_time and that's fine..
but I would like to convert that cycle units to time units. I don't know how
to do it... Maybe with loops_per_jiffies and do_div but I don't know how to
combine them. What is a jiffie (4 ms as wikipedia said in 2.6 kernel series)
and how can I use them to convert the rdtscll return value to time units?
Hi,
You can use the "jiffies" variable in the kernel to do so. Here is how
you do it:
unsigned long i, j;
i = jiffies;
function()
j = jiffies;
printk(" function took %ul mili secs",
jiffies_to_msecs(j-i) );
Thanks,
Rajat
--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
FAQ: http://kernelnewbies.org/faq/
