On Fri, 2004-06-25 at 16:49 +0530, Dhiman, Gaurav wrote: > need_resched is not something specific to a particular process and is > not a part of task_struct, its global to kernel and is set by timer > interrupt whenever the timer interrupt finds that the time allocated to > current process (represented by 'current' pointer) has expired. This is not true. need_resched is a flag in the process's thread_info struct. It is per- process, for performance reasons. > Your first question is my question also, How the returning code of any > interrupt finds whether the control is returning to user space or kernel > space? As far as I think, it must be checking if the return address > falls in kernel address range or in user address range. Can someone give > the detailed insight about this? Yes, this is basically what it does. The interrupts have to know whether to jump back to a kernel address or mode switch back to user- space, so there are different code paths. Robert Love -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
