Hi, On Wed, Dec 29, 2010 at 9:30 AM, CP YEH <ntdev74@gmail.com> wrote:

Hi,

I would like to know if I can obtain thread id of calling thread. Let me clarify what I mean by this.

First, here is task_struct from linux kernel code.

struct task_struct {       struct list_head tasks;       pid_t pid;       pid_t tgid;       struct task_struct *group_leader;  /* threadgroup leader */       struct list_head thread_group; };

I understand that getpid returns tgid and gettid via __NR_gettid returns tid but according to manpage, it seems to me that it is same as what I get from getpid().

Man page of gettid:       gettid() returns the thread ID of the current process.  This is equal to the       process ID (as returned by getpid(2)), unless  the  process  is  part  of  a       thread  group

However, I would like to obtain pid of task_struct. Is there any way I can get that information?

From my understanding, this sort of depends on which threading model is being employed.

For standard distros (like ubuntu), I believe that getpid returns the tgid, and gettid (aka syscall( 224 )) returns pid of the task struct (which is really a thread id). Dave Hylands