Allocate pager bufs from UMA instead of 80-ish mutex protected linked list.

o In vm_pager_bufferinit() create pbuf_zone and start accounting on how many
  pbufs are we going to have set.
  In various subsystems that are going to utilize pbufs create private zones
  via call to pbuf_zsecond_create(). The latter calls uma_zsecond_create(),
  and sets a limit on created zone. After startup preallocate pbufs according
  to requirements of all pbuf zones.

  Subsystems that used to have a private limit with old allocator now have
  private pbuf zones: md(4), fusefs, NFS client, smbfs, VFS cluster, FFS,
  swap, vnode pager.

  The following subsystems use shared pbuf zone: cam(4), nvme(4), physio(9),
  aio(4). They should have their private limits, but changing that is out of
  scope of this commit.

o Fetch tunable value of kern.nswbuf from init_param2() and while here move
  NSWBUF_MIN to opt_param.h and eliminate opt_swap.h, that was holding only
  this option.
  Default values aren't touched by this commit, but they probably should be
  reviewed wrt to modern hardware.

This change removes a tight bottleneck from sendfile(2) operation, that
uses pbufs in vnode pager. Other pagers also would benefit from faster
allocation.

Together with:	gallatin
Tested by:	pho

0 files changed, 0 insertions, 0 deletions