Re: [patch] sched: unlocked context-switches

[David Mosberger <davidm@napali.hpl.hp.com>]

>>>>> On Tue, 12 Apr 2005 08:42:53 +0200, Ingo Molnar <mingo@elte.hu> said:

  Ingo> * David Mosberger <davidm@napali.hpl.hp.com> wrote:

  >> Now, Ingo says that the order is reversed with his patch, i.e.,
  >> switch_mm() happens after switch_to().  That means flush_tlb_mm()
  >> may now see a current->active_mm which hasn't really been
  >> activated yet.  That should be OK since it would just mean that
  >> we'd do an early (and duplicate) activate_context().  While it
  >> does not give me a warm and fuzzy feeling to have this
  >> inconsistent state be observable by interrupt-handlers (and, in
  >> particular, IPI-handlers), I don't see any problem with it off
  >> hand.

  Ingo> thanks for the analysis. I fundamentally dont have any fuzzy
  Ingo> feeling from having _any_ portion of the context-switch path
  Ingo> nonatomic, but with more complex hardware it's just not
  Ingo> possible it seems.

No kidding! ;-)

I _think_ the change is OK.  I'll need testing, of course.
Sure would be nice to have 2.7.xx...

Thanks,

	--david