git: kernel - Break up scheduler and loadavg callout

[Matthew Dillon]

commit 586c43085fc900273732f99de6c9ef43f73ded76
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date:   Sat Aug 12 12:24:16 2017 -0700

    kernel - Break up scheduler and loadavg callout
    
    * Change the scheduler and loadavg callouts from cpu 0 to all cpus, and
      adjust the allproc_scan() and alllwp_scan() to segment the hash table
      when asked.
    
      Every cpu is now tasked with handling the nominal scheduler recalc and
      nominal load calculation for a portion of the process list.  The portion
      is unrelated to which cpu(s) the processes are actually scheduled on,
      it is strictly a way to spread the work around, split up by hash range.
    
    * Significantly reduces cpu 0 stalls when a large number of user processes
      or threads are present (that is, in the tens of thousands or more).  In
      the test below, before this change, cpu 0 was straining under 40%+
      interupt load (from the callout).  After this change the load is spread
      across all cpus, approximately 1.5% per cpu.
    
    * Tested with 400,000 running user processes on a 32-thread dual-socket
      xeon (yes, these numbers are real):
    
      12:27PM  up 8 mins,  3 users, load avg: 395143.28, 270541.13, 132638.33
      12:33PM  up 14 mins, 3 users, load avg: 399496.57, 361405.54, 225669.14
    
    * NOTE: There are still a number of other non-segmented allproc scans in
    	the system, particularly related to paging and swapping.
    
    * NOTE: Further spreading-out of the work may be needed, by using a more
      	frequent callout and smaller hash index range for each.

Summary of changes:
 sys/kern/imgact_elf.c         |  2 +-
 sys/kern/init_main.c          |  2 +-
 sys/kern/kern_descrip.c       |  4 +--
 sys/kern/kern_ktrace.c        |  4 +--
 sys/kern/kern_proc.c          | 30 ++++++++++++++++---
 sys/kern/kern_resource.c      |  8 ++---
 sys/kern/kern_sig.c           |  2 +-
 sys/kern/kern_synch.c         | 70 +++++++++++++++++++++++++++++++------------
 sys/kern/vfs_syscalls.c       |  4 +--
 sys/sys/globaldata.h          |  8 ++++-
 sys/sys/proc.h                |  6 ++--
 sys/vfs/procfs/procfs_vnops.c |  2 +-
 sys/vm/vm_glue.c              |  7 +++--
 sys/vm/vm_meter.c             |  2 +-
 sys/vm/vm_object.c            |  2 +-
 sys/vm/vm_pageout.c           |  4 +--
 16 files changed, 111 insertions(+), 46 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/586c43085fc900273732f99de6c9ef43f73ded76


-- 
DragonFly BSD source repository