linux-kernel - [RFC 0/2] Replace PID implementation with IDR API

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Date:   Sat,  9 Sep 2017 18:03:15 +0530
From:   Gargi Sharma <gs051095@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     riel@...riel.com, julia.lawall@...6.fr, akpm@...ux-foundation.org,
        mingo@...nel.org, pasha.tatashin@...cle.com, ktkhai@...tuozzo.com,
        oleg@...hat.com, wangkefeng.wang@...wei.org,
        Gargi Sharma <gs051095@...il.com>
Subject: [RFC 0/2] Replace PID implementation with IDR API

This patch series replaces kernel bitmap implementation of PID allocation
with IDR API.

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
   3602        324          8       3934        f5e    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
   2858        216         16       3090        c12    kernel/pid_namespace.o

There wasn't a considerable difference between the time required for
allocation of PIDs to the processes. The IDR implementation is a little faster
than bitmap implementation.

The next change in the pipeline is replacing pidhash with IDR API implementation.

Gargi Sharma (2):
  proc: Return if nothing to unmount
  pid: Replace PID bitmap implementation with IDR API

 fs/proc/base.c                |   4 +
 include/linux/pid.h           |   1 +
 include/linux/pid_namespace.h |   5 +-
 init/main.c                   |   4 +-
 kernel/pid.c                  | 204 ++++++++----------------------------------
 kernel/pid_namespace.c        |  39 ++++----
 6 files changed, 63 insertions(+), 194 deletions(-)

-- 
2.7.4