Hi all,
Currently I'm going through book 'development of Linux kernel' by Robert
Love.
In the chapter 'Process Management' I read below sentence
"Linux has a unique implementation of threads: It does not differentiate
between threads and processes. To Linux, a thread is just a special kind
of process."
In kernel everything is a just task represented by *task_struct
*
And from some other sources I understand that there is a one-one mapping
between threads created by library API and kernel threads.
Now my questions are :
1. I have Program and I've created two threads say T1 and T2 using
Posix Thread Library. see below
*void* function2()
{
while(1)
{
printf("I'm Thread 2\n");
sleep(1);
}
}
void* function1()
{
printf("I'm Thread 1\n");
char buf[1024];
read(1,buf,1023); // Thread 1 will block here
}
int main(int argc,char *argv[])
{
pthread_t pid1,pid2;
pthread_create(&pid1,NULL,function1,NULL);
pthread_create(&pid2,NULL,function2,NULL);
while(1)
{
printf("I'm Main Thread\n");
sleep(1);
}
}
*
According my understanding there will be three tasks will be created in
the kernel after I ran this program. One is for main process say P and
other two for T1 and T2.
And T1 & T2 share the address space of P. Is my understanding is correct?
2.Regarding the scheduling.
Upon running the above program , the output is:
* I'm Main Thread
I'm Thread 1
I'm Thread 2
I'm Main Thread
I'm Thread 2
I'm Main Thread
I'm Thread 2
I'm Main Thread
I'm Thread 2
I'm Main Thread
I'm Thread 2
* Though Thread 1 is blocked Main Thread and Thread 2 are still
running.
That means different user-level threads are scheduled by kernel
separately.Is this correct ?
If this is correct how time slices will be allocated?
Do please some body clarify my questions and also provide some good
links as references
Thank you all
Regards,
Ravikumar
