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
Attachment:
signature.asc
Description: Digital signature
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
