Nice approach....
Some general comments are
-The while loop can be in an ioctl rather than in the init_module. So that you
can do repeated testing.
-The condition (jiffies != num) can be dangerous, especially in a preemptible
kernel, it should be (jiffies < num) otherwise there is a danger of going into
an infinite loop.
-If init_module returns -1, I don't think it would be successfully loaded. Done
intentionally ?
If the above were a result of a quickly written module then please ignore the
comments.
Gopu.
-----Original Message-----
From: Sangharsha p g
Sent: Tuesday, August 17, 2004 2:20 PM
To: Gopu Bhaskar (WT01 - EMBEDDED & PRODUCT ENGINEERING SOLUTIONS)
Cc: ilugc@xxxxxxxxxxxxx
Subject: Re: [Ilugc] RE:Kernel 2.6
?
Thanks a lot for the reply, I will do that, I have given small kernel module
which I feel this is the way of testing preemptiveness of the kernel.The below
shown module I am using
#define __KERNEL__
#define MODULE
#include<linux/kernel.h>
#include<linux/module.h>
#include<linux/sched.h>
static int init_module(void)
{
unsigned long num=jiffies+(10*HZ);
while(jiffies!=num) {
? //schedule(); /* uncomment this line to relinquish the CPU*/
? ? ? ? }
return -1;
}
static void cleanup_module(void)
{
? ? ? ? printk("module unloaded\n");
}
When you try to load the above module since it is a non-preemptible kernel, it
will in that loop for 10 secs(since it is jiffies+(10*HZ)).So during that U try
type some thing OR try to move the mouse since it is non-premtible kernel you
can't do anything.If it is a pr-emtible it will allow you to do so(This is what
my way of testing if any comments OR better way of testing pls let me know).
Regards,
Sangharsh
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