Thanks for your reply. Could please tell or send me a link which can help me to build & install user mode linux. I have never worked with user mode linux, so I request to please guide me over this. This will a great help to understand the code flow in kernel. >I am quite sure you neither need nor want to access > the runqueue. I am novice in kernel programming and trying to learn by implementing practically. I was thinking of a case where someone needs to have a kernel modules and that module will keep of a zombie objects created per user and this information can be retrieved by /proc filesystem. That's why I was trying to get the hold of runqueue and traverse it for zombie process. User mode linux sounds to be nice technique. Please give more inputs as being novice i will be requiring your initial guidance. Regards Dinesh --- Jan Hudec <bulb@xxxxxx> wrote: > On Thu, May 19, 2005 at 04:15:41 +0100, Dinesh Ahuja > wrote: > > Hi All, > > > > I am implementing Blocking I/O techniques in > device > > driver and want to understand the fu nctionality > of > > schedule() function i.e how the process [ > represented > > by task_struct ] switch from wait_queue to > run_queue. > > > > To understand the code flow, i want to adopt the > > simplest technique which is quick and effective. > If I > > put printk() in schedule() function, i need to > compile > > the kernel which i somewhat time consuming. Is > there > > any easier way so that I can understand the flow > from > > the module to kernel code and could see what is > code > > flow in kernel. > > You can build user-mode-linux, to which you can > attach debugger. It's > a hell lot safer than playing with live kernel and > you don't need to > work as root. > > On the other hand, I don't see what's the problem. > From module's point > of view, schedule() is a thing, that sleeps for some > time (and the CPU > is doing other work meanwhile). You just have to > note, that the other > thing can be your module called on behalf of other > process. > > When schedule() returns is controlled by the task > state. > IIRC set_current_state() is the appropriate macro to > set that. > > Btw., most of the time you don't want to call > schedule() directly, but > rather with wait_event (or wait_event_interruptible) > or do semaphore or > completion operations. > > > Another question is , i need to access runqueue > from > > my module, but the kernel doesnot export the > functions > > needs to work on runqueue. Please guide me how to > > accesses functions which are not exported by > kernel in > > kernel module. > > I am quite sure you neither need nor want to access > the runqueue. You > may want to make process go to different queues, but > that's done by > setting their state. Or, even more probably, hidden > in wait_event and > wake_up. > > ------------------------------------------------------------------------------- > Jan 'Bulb' Hudec <bulb@xxxxxx> > ________________________________________________________________________ Yahoo! India Matrimony: Find your life partner online Go to: http://yahoo.shaadi.com/india-matrimony -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
