-----Original Message----- From: amith [mailto:amith@xxxxxxxxxxxxxxx] Sent: Monday, August 02, 2004 10:44 AM To: Nilanjan Roychowdhury Subject: Re: linux threads Nilanjan Roychowdhury wrote: >If I create two threads using pthread_create calls in linux does the kernel sees them as two schedulable entities ?? I can see two LWP with diff PIds. > yes. hence they have different PID's. But if u create user-space threads then it is seen by the kernel as one process and hence the time-slice for the process (which creaated the thread) is divided between threads created by the process. Now, in this case (pthread) they are not user-space threads (pthread -> kernel level threads) and hence each new thread gets a new time slice and runs on the CPU. Another advantage of using kernel-level threads like pthread is it takes advantage of SMP machines where a thread can be scheduled on a diff CPU. where as the user-level threads cannot run on different CPU's since they are not visible to the kernel as different processes (or entities to be shceduled) . in case you want to try both kernel -level and user-space threads there are 2 libraries available.Use pthreads for kernel threads or GNU Portable Threads (Pth) for user space threads. > > >Secondly lets say if I create a thread in process A create another thread in process B then can I control the scheduling between them. > scheduling between threads in different unrelated processes ?? Yes I mean scheduling between threads in two diff processes. Like currently I am executing thread 1 from process A and then I attach my execution ( definitely after blocking the prev thread) to thread 2 from process B . Is it possible ??? > > >Basically the kernel scheduler is thread aware or not?? > yes it is. it depends on what u mean by thread aware actually ;-) ! By "thread aware" I mean threads should be visible to the scheduler. cheers, Amith > > > >-- >Kernelnewbies: Help each other learn about the Linux kernel. >Archive: http://mail.nl.linux.org/kernelnewbies/ >FAQ: http://kernelnewbies.org/faq/ > > -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
