Hi Daniel... Here comes my thoughts.... On Sat, Jan 16, 2010 at 8:24 AM, Daniel (Youngwhan) Song <breadncup@xxxxxxxxx> wrote: > 1. It seems that the concept of thread in the linux kernel is lightweight > process. Is this right? Yes. A bit OOT, in Windows, there's a lighter form than thread called fiber. But in Linux, thread (NPTL, if we want to be specific) is the actualization of LWP. > 1-1 If it is right, are both kernel thread and user-space thread (pthread) > lightweight process? Or does the lightweight process mean only to kernel > thread? IMHO, LWP (Light Weight Process) is a concept which can be applied in both space. However, there is correlation between user space thread and kernel space thread. IIRC, in NPTL, the relationship is 1:1 thus one user space thread is running on top of one kernel thread. (sorry if I use wrong words, but hopefully you get it) Other threading implementation could do it differently e.g many user space threads inside one thread group are multiplexed on top of one kernel space thread > 2. I guess the instance from fork() is a process in user application, and > the instance from pthread_create() is a thread. Correct >The former process is heavy > weight process having copy-on-write feature and the later thread is managed > by pthread library handled in user mode. Is this right? Right, with additionaly note: pthread_create eventually calls clone() with CLONE_VM and CLONE_THREAD flags IIRC. fork() calls clone() too but without those two flags. So you can say, both essentially some similar operations (e.g creating new task structs) but the rest is different (one is creating whole address space, the other is not). > Any help would be appreciated. Thanks, Hopefully it makes things clearer :) -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
