[PATCH v3 0/2] Replace PID bitmap allocation with IDR API

[Gargi Sharma <gs051095@gmail.com>]

This patch series replaces kernel bitmap implementation of PID allocation
with IDR API. These patches are written to simplify the kernel by replacing custom code with calls to generic code.

The following are the stats for pid and pid_namespace object files
before and after the replacement. There is a noteworthy change between
the IDR and bitmap implementation.

Before
text       data        bss        dec        hex    filename
   8447       3894         64      12405       3075    kernel/pid.o
After
text       data        bss        dec        hex    filename
   3397        304          0       3701        e75    kernel/pid.o

Before
 text       data        bss        dec        hex    filename
   5692       1842        192       7726       1e2e    kernel/pid_namespace.o
After
text       data        bss        dec        hex    filename
   2854        216         16       3086        c0e    kernel/pid_namespace.o

The following are the stats for ps, pstree and calling readdir on /proc
for 10,000 processes.

ps:
	With IDR API	With bitmap
real	0m1.479s	0m2.319s
user	0m0.070s	0m0.060s
sys	0m0.289s	0m0.516s

pstree:
	With IDR API	With bitmap
real	0m1.024s	0m1.794s
user    0m0.348s	0m0.612s
sys	0m0.184s	0m0.264s

proc:
	With IDR API	With bitmap
real    0m0.059s	0m0.074s
user    0m0.000s	0m0.004s
sys	0m0.016s	0m0.016s

---
Changes in v3:
	- Replace idr_next with idr_get_cursor().
	- Correct pid_alloc so that find_pid_ns can't
	  find not completely allocated pids.
Changes in v2:
        - Removed redundant  IDR function that was introduced
          in the previous patchset.
        - Renamed PIDNS_HASH_ADDING
        - Used idr_for_each_entry_continue()
        - Used idr_find() to lookup pids

Gargi Sharma (2):
  pid: Replace pid bitmap implementation with IDR API
  pid: Remove pidhash

 arch/powerpc/platforms/cell/spufs/sched.c |   2 +-
 fs/proc/loadavg.c                         |   2 +-
 include/linux/init_task.h                 |   1 -
 include/linux/pid.h                       |   2 -
 include/linux/pid_namespace.h             |  18 +--
 init/main.c                               |   3 +-
 kernel/fork.c                             |   2 +-
 kernel/pid.c                              | 245 ++++++------------------------
 kernel/pid_namespace.c                    |  48 ++----
 9 files changed, 68 insertions(+), 255 deletions(-)

-- 
2.7.4