CVS commit: src/sys

["Andrew Doran" <ad%netbsd.org@localhost>]

Module Name:    src
Committed By:   ad
Date:           Sun Apr 19 21:11:43 UTC 2020

Modified Files:
        src/sys/kern: subr_vmem.c
        src/sys/sys: vmem_impl.h

Log Message:
- Fix uneven performance with "bursty" vmem arenas.  Adjust locking so that
  the mutex is acquired and released only once in the happy path.  Align
  tags to cachelines.  Size the hash table according to the maximum count of
  boundary tags over the interval just gone, not the instantaneous count,
  and decay that maximum value by 50%+1 after each rehash.  Round up to the
  next power of two to eliminate divisions.  Do the rehash check unlocked.

- Hash bucket size is sizeof(vmem_hashlist), not size of a pointer to same.


To generate a diff of this commit:
cvs rdiff -u -r1.100 -r1.101 src/sys/kern/subr_vmem.c
cvs rdiff -u -r1.3 -r1.4 src/sys/sys/vmem_impl.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.