thanks
On Sat, Feb 13, 2016 at 2:19 PM, Henrik Austad <henrik@xxxxxxxxx> wrote:
On Sat, Feb 13, 2016 at 11:42:57AM +0530, Nitin Varyani wrote:
> Hello,
Hi Nitin,
> I want to understand the flow of code of process scheduler of
> linux kernel. What I have understood is that
> The task marks itself as sleeping,
> puts itself on a wait queue,
> removes itself from the red-black tree of runnable, and
> calls schedule() to select a new process to execute.
>
> for Waking back up
> The task is set as runnable,
> removed from the wait queue,
> and added back to the red-black tree.
>
> Can I get the details of which function does what? in sched/core.c and in
> sched/fair.c
> I am concerned only with fair scheduler. There are so many functions in
> these two files that I am totally confused.
Then core.c and fair.c is the best bet.
You could also pick up a copy of Linux kernel development (By Love), it
gives a nice introduction to the overall flow of .. well mostly everything.
:)
In kernel/sched/sched.h you have a struct called 'struct sched_class" which
is a set of function-points. This is used by the core machinery to call
into scheduling-class specific code. At the bottom of fair.c, you see said
struct being populated.
Also, if you want to see what really happens, try enabling
function-tracing, but limit it to sched-functions only (and sched-events,
those are also useful to see what triggers things)
mount -t debugfs nodev /sys/kernel/debug
cd /sys/kernel/debug/tracing
echo 0 > tracing_on
echo function > current_tracer
echo "sched*" > set_ftrace_filter
echo 1 > events/sched/enable
echo 1 > tracing_on
... wait for a few secs
echo 0 > tracing_on
cat trace > /tmp/trace.txt
Now, look at trace.txt and correlate it to the scheduler code :)
Good luck!
--
Henrik Austad
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
