mpsafe psm driver needed

John Baldwin jhb at
Mon Jan 14 06:32:39 PST 2008

On Monday 14 January 2008 06:00:54 am Philip Paeps wrote:
> On 2008-01-13 21:25:03 (+0100), Kris Kennaway <kris at> wrote:
> > I've been looking at some mutex profiling traces from users of 6.x and 7.x 
> > who are reporting that their mouse pointer sometimes freezes when their 
> > system is busy.  In most of the situations I have looked at this is because 
> > the psm driver is Giant-locked, and competes with other things like the 
> > syncer (in 6.x), or sysctl calls (I have a WIP for this that I need to 
> > revisit).
> > 
> > This is a minor problem from a grand architectural point of view but an 
> > important one from a usability point of view.  I believe these particular 
> > interactivity problems would be resolved if the psm driver no longer 
> > required Giant.  Is anyone able to work on this?
> I have taken a look at this in the past.  It's not a trivial problem.
> There is a lot of what I can only charitably call "legacy code" in psm and it
> appears that as soon as you touch any of it, it upsets at least one brand of
> KVM "out there".
> One of my mentees has been working on a rewrite for a while, but the project
> has not yet been committed to cvs.
> jls: any news on this?

Does psm(4) interface with any subsystems like tty(4)?

John Baldwin

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