Re: mutexes, IPL, tty locking

[David Holland <dholland-tech%netbsd.org@localhost>]

On Tue, Feb 09, 2010 at 12:20:48AM +0000, YAMAMOTO Takashi wrote:
 > > I'm not suggesting that we use this as such (and it would take quite a
 > > bit of work to merge it) but I think the general approach is worth
 > > considering.
 > 
 > i don't think it's worth to do at this point because
 > - much complexity for little gain.
 > - it involves more frequent change of the effective IPL, which might
 >   be expensive.

Well, there's the other point, which I admittedly didn't make very
prominent, which is that all that code is MI and the MD code is
reduced to just a single cpu_setipl() function.

It can easily (much more easily than deploying it in the first place)
be made to take the same shortcut we currently do, that is, never
lowering the ipl except to 0.

-- 
David A. Holland
dholland%netbsd.org@localhost