cvs commit: src/sys/kern sched_ule.c

Jeff Roberson jeff at
Thu Jan 4 04:16:20 PST 2007

jeff        2007-01-04 12:16:19 UTC

  FreeBSD src repository

  Modified files:
    sys/kern             sched_ule.c 
   - Only allow the tdq_idx to increase by one each tick rather than up to
     the most recently chosen index.  This significantly improves nice
     behavior.  This allows a lower priority thread to run some multiple of
     times before the higher priority thread makes it to the front of
     the queue.  A nice +20 cpu hog now only gets ~5% of the cpu when running
     with a nice 0 cpu hog and about 1.5% with a nice -20 hog.  A nice
     difference of 1 makes a 4% difference in cpu usage between two hogs.
   - Track a seperate insert and removal index.  When the removal index is
     empty it is updated to point at the current insert index.
   - Don't remove and re-add a thread to the runq when it is being adjusted
     down in priority.
   - Pull some conditional code out of sched_tick().  It's looking a bit
     large now.
  Revision  Changes    Path
  1.173     +52 -22    src/sys/kern/sched_ule.c

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