Date: Mon, 14 Jan 2008 16:09:40 +0100 From: Philip Paeps <philip@freebsd.org> To: psionic+spamtest@gmail.com Cc: jls@freebsd.org, current@freebsd.org Subject: Re: mpsafe psm driver needed Message-ID: <20080114150940.GO17508@fasolt.home.paeps.cx> In-Reply-To: <200801140920.12890.jhb@freebsd.org> References: <478A739F.2030003@FreeBSD.org> <20080114110054.GK17508@fasolt.home.paeps.cx> <200801140920.12890.jhb@freebsd.org>
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On 2008-01-14 09:20:11 (-0500), John Baldwin <jhb@freebsd.org> wrote: > On Monday 14 January 2008 06:00:54 am Philip Paeps wrote: > > On 2008-01-13 21:25:03 (+0100), Kris Kennaway <kris@FreeBSD.org> 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)? It shouldn't. moused(8) listens on /dev/psm and sends events down again to syscons with /dev/consctl. (And syscons then pushes them back up through /dev/sysmouse for things like X11 to listen on - yikes). - Philip -- Philip Paeps Please don't Cc me, I am philip@freebsd.org subscribed to the list. <foo> lo azz <azz> lo azz <azz> gah <azz> lo foo
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