Re: uarea swap-out

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

On Fri, Aug 28, 2009 at 10:59:06PM +0100, Mindaugas Rasiukevicius wrote:

> http://www.netbsd.org/~rmind/uarea_swapout4.diff

- Suggest leaving the ps keywords in place and documented.  Removing them
  could break scripts, and leaving them in serves as a reminder not to reuse
  the same flag letters in the display.  top and systat are by and large
  visual so I don't have the same concern about them.  Benfit of removing
  them is only cosmetic.

- You can probably get rid of XS_CTL_DATA_ONSTACK.

- lwp_t::l_swaplock: worth leaving as a reserved field?

- uvmexp_sysctl::swapins, swapouts: would leave these and not rename so you
  don't break compilation of third party software.  Consider the various X
  widgets that display graphs and so on.

- As an aside, elimination of pmap_collect() gets us a closer to the
  simplification of pmap locking that I proposed earlier this year - where
  MD page manipluation are implicitly locked by caller using the containing
  object's lock (uvm_object and/or amap). It also allows lockless
  pmap_extract() to be safe again - I can't remember if I disabled this. It
  was unsafe because pmap_collect() was a "side channel" where PTEs and so
  on could be ripped out from under the process even with the correct
  uvm_object/amap locked.

Thanks!