On Sun, May 10, 2009 at 4:56 PM, Chetan Nanda <[email protected]> wrote: > > > On Fri, May 8, 2009 at 7:34 PM, Mulyadi Santosa <[email protected]> > wrote: >> >> On Fri, May 8, 2009 at 4:42 PM, Chetan Nanda > >> >I am still confused, as every thread will be having its own register set >> > and >> > this set will get stored in its 'tast_struct' at each context switch and >> > at >> > next run registers will get populated from corresponding 'task_struct'. >> > >> > So how these variable will get shared between different threads? I am >> > missing any basic thing? >> >> The original poster use pthreads, and pthreads are created by using >> CLONE_VM flag of clone() syscall. That means, they're sharing task >> struct, process address space etc. > > AFAIK, each thread or process in kernel has its own 'task_struct'. It is not > shared with any other thread though several elements of this, like > signal_struct, fs_struct, may be shared with other threads in system. > > Now at every context switch all processor registers (called hardware context > of a thread) get stored in task_struct. Thus each thread will be having a > local copy of all processor registers. Thus there will not be any race > condition in program posted by original poster. CMIMW > > Thanks, > Chetan Nanda > >> >> regards, >> >> Mulyadi. > >
The race condition in OP's code can be easily reproduced by making the LOOPCOUNT to 10000 and running the program multiple times on a SMP machine. So, I am unable to follow the arguments about thread private registers etc. Anything missing here? Regards, Sandeep. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
