git: kernel - Remove proc_token, replace proc, pgrp, and session structure backend

[Matthew Dillon]

commit b22b6ecd66ef2104abc07ae243f04125b30aa38d
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Thu Oct 24 21:54:48 2013 -0700

    kernel - Remove proc_token, replace proc, pgrp, and session structure backend
    
    * Isolate the remaining exposed topology for proc, pgrp, and session
      into one source file (kern_proc.c).
    
    * Remove allproc, zombproc, pgrp's spinlocks, and start tracking session
      structures so we don't have to indirect through other system structures.
    
    * Replace with arrays-of-lists, 1024 elements, including a 1024 element
      token lock array to protect each list.
    
          proc_tokens[1024]
          allprocs[1024]
          allpgrps[1024]
          allsessn[1024]
    
      This removes nearly all the prior proc_token contention and also removes
      process-group processing contention and makes it easier to track tty
      sessions.
    
    * Normal process, Zombie processes, the original linear list, and the
      original has mechanic are now all combined into a single allprocs[]
      table.  The various API functions will filter out zombie vs non-zombie
      based on the type of request.
    
    * Rewrite the PID allocator to take advantage of the hashed array topology.
      An atomic_fetchadd_int() is used on the static base value which will cause
      each cpu to start at a different array entry, thus removing SMP conflicts.
    
      At the moment we iterate the relatively small number of elements in the
      bucket to find a free pid.
    
      Since the same proc_tokens[n] lock applies to all three arrays (proc,
      pgrp, and session), we can validate the pid against all three at the
      same time with a single lock.
    
    * Rewrite the procs sysctl to iterate the hash table.  Since there are
      1024 different locks, a 'ps' or similar operation no longer has any
      significant effect on system performance, and 'ps' is VERY fast now
      regardless of the load.
    
    * poudriere bulk build tests on a blade (4 core / 8 thread) shows virtually
      no SMP collisions even under extreme loads.
    
    * poudriere bulk build tests on monster (48-core opteron) show very low
      SMP collision statistics outside of filesystem writes in most situations.
      Pipes (which are already fine-grained) sometimes show significant
      collisions.
    
      Most importantly, NO collisions on the process fork/exec/exit critical
      path, end-to-end.  Not even in the VM system.

Summary of changes:
 sys/kern/init_main.c |   3 +-
 sys/kern/kern_proc.c | 587 +++++++++++++++++++++++++++++----------------------
 sys/sys/proc.h       |  23 +-
 3 files changed, 347 insertions(+), 266 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/b22b6ecd66ef2104abc07ae243f04125b30aa38d


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