On Linux or any UNIX platform process with PID 1 is init process and process with PID 0 is a swapper process.
A process on a UNIX system is created by fork system call. Every process except the process with PID 0 is created when another process executes the fork system call. The Process 0 is created by hand when the system boots; after forking a child (process with PID 1), process 0 becomes the swpper process. Process 1, is known as init, and is the ancestor of every other process in the system.
The command "ps -p 1" will show the process having PID=1, this is how the output looked on my machine.
lopgod50:~ # ps -p 1 -o pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm
PID TID CLS RTPRIO NI PRI PSR %CPU STAT WCHAN COMMAND
1 1 TS - 0 23 1 0.0 S schedule init
Check the same for process having PID 0 use command ps -p0
Thanks and Regards,
Prasad.
On 6/7/07,
Devvrat Tripathi <tripathidevvrat@xxxxxxxxx> wrote:
On 6/7/07, Devvrat Tripathi < tripathidevvrat@xxxxxxxxx> wrote:On 6/7/07, Erik Mouw <mouw@xxxxxxxxxxxx > wrote:-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On Thu, Jun 07, 2007 at 12:02:03PM +0200, Devvrat Tripathi wrote:
> I wanted to ask you if current pid will work at the driver level. i used in
> pci-gart.c to get the processes which are using DMA transfer but stragely i
> get 0 sometimes and sometime proper pid's.
0 is a proper pid as well, it's the "swapper" task.
Erik
what is a "Swapper" task. Can you explain what work does it do and why does it do so many IO transfers.
devvrat
Also this is what wikipedia says of idle task.
" In Unix-like operating systems such as Linux, the idle task has process ID zero, and never exits. "
but the results which i am getting show that this task does exist and is initiating so many DMA transfers. what can be the possible reason for it or is it that i am missing something?
devvrat
