mpsafe psm driver needed

Philip Paeps philip at
Mon Jan 14 03:24:11 PST 2008

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?

 - Philip

Philip Paeps                                    Please don't Cc me, I am
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  It is impossible for an optimist to be pleasantly

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