It adds lots of CPU scheduler stats in /proc/pid/stat.  They are described in
the new Documentation//sched-stats.txt

We were carrying this patch offline for some time, but as there's still
considerable ongoing work in this area, and as the new stats are a
configuration option, I think it's best that this capability be in the base
kernel.

Nick removed a fair amount of statistics that he wasn't using.  The full patch
gathers more information.  In particular, his patch doesn't include the code
to measure the latency between the time a process is made runnable and the
time it hits a processor which will be key to measuring interactivity changes.

He passed his changes back to me and I got finished merging his changes with
the current statistics patches just before OLS.  I believe this is largely a
superset of the patch you grabbed and should port relatively easily too.

Versions also exist for

    2.6.8-rc2
    2.6.8-rc2-mm1
    2.6.8-rc2-mm2

at
    http://eaglet.rain.com/rick/linux/schedstat/patches/

and within 24 hours at

    http://oss.software.ibm.com/linux/patches/?patch_id=730&show=all

The version below is for 2.6.8-rc2-mm2 without the staircase code and has
been compiled cleanly but not yet run.

From: Ingo Molnar <mingo@elte.hu>

this code needs a couple of cleanups before it can go into mainline:

fs/proc/array.c, fs/proc/base.c, fs/proc/proc_misc.c:

 - moved the new /proc/<PID>/stat fields to /proc/<PID>/schedstat,
   because the new fields break older procps. It's cleaner this way
   anyway. This moving of fields necessiated a bump to version 10.

Documentation/sched-stats.txt:

 - updated sched-stats.txt for version 10

 - wake_up_forked_thread() => wake_up_new_task()

 - updated the per-process field description

Kconfig:

 - removed the default y and made the option dependent on DEBUG_KERNEL. 
   This is really for scheduler analysis, normal users dont need the 
   overhead.

include/linux/sched.h:

 - moved the definitions into kernel/sched.c - this fixes UP compilation
   and is cleaner.

 - also moved the sched-domain definitions to sched.c - now that the 
   sched-domains internals are not exposed to architectures this is
   doable. It's also necessary due to the previous change.

kernel/fork.c:

 - moved the ->sched_info init to sched_fork() where it belongs.

kernel/sched.c:

 - wake_up_forked_thread() -> wake_up_new_task(), wuft_cnt -> wunt_cnt,
   wuft_moved -> wunt_moved.

 - wunt_cnt and wunt_moved were defined by never updated - added the 
   missing code to wake_up_new_task().

 - whitespace/style police

 - removed whitespace changes done to code not related to schedstats -
   i'll send a separate patch for these (and more).
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>