[PATCH 0/4] /proc/schedstat and /proc/sched_debug fail at 4096

[Nathan Zimmer <nzimmer@sgi.com>]

When running with 4096 cores attemping to read /proc/schedstat,
/proc/sched_debug, /proc/timer_list will fail with an ENOMEM condition.
On a sufficantly large systems the total amount of data is more then 4mb, so
it won't fit into a single buffer.  The failure can also occur on smaller
systems when memory fragmentation is high.

An solution considered but not tried for sched_stat and scheddebug would to be
create an alternative mechanism to single_open but rather then calling *_show
once it calls show once per possible cpu.  If someone feels strongly that is
the way to go I can give it a spin.

Nathan Zimmer (4):
  procfs: /proc/sched_stat fails on very very large machines.
  procfs: /proc/sched_debug fails on very very large machines.
  /proc/timer_list split timer_list_show_tickdevices
  Convert timer list to be a proper seq_file.

 kernel/sched/debug.c     |   84 +++++++++++++++++++++++++++++++++-----
 kernel/sched/stats.c     |   73 ++++++++++++++++++++++++---------
 kernel/time/timer_list.c |  102 +++++++++++++++++++++++++++++++++++++---------
 3 files changed, 209 insertions(+), 50 deletions(-)