mouse interactivity (Re: svn commit: r182109 - head/sys/dev/syscons)

Marius Nünnerich marius at
Tue Aug 26 10:28:25 UTC 2008

On Mon, Aug 25, 2008 at 4:19 PM, Ed Schouten <ed at> wrote:
> * Kris Kennaway <kris at> wrote:
>> Ed Schouten wrote:
>>> Author: ed
>>> Date: Sun Aug 24 15:20:44 2008
>>> New Revision: 182109
>>> URL:
>>> Log:
>>>   Make sysmouse(4) use its own locks, instead of using Giant.
>>>     When I changed syscons(4) to work with the MPSAFE TTY code, I just
>>>   locked all device nodes down using the compatibility feature that allows
>>>   you to override the TTY's lock (Giant in this case). Upon closer
>>>   inspection, it seems sysmouse(4) only has two internal variables that
>>>   need locking: mouse_level and mouse_status.
>>>     I haven't done any performance benchmarks on this, though I think
>>> it
>>>   won't have any dramatic improvements on the system. It is good to get
>>>   rid of Giant here, because the third argument of tty_alloc() has only
>>>   been added to ease migration to MPSAFE TTY. It should not be used when
>>>   not needed.
>>>     While there, remove SC_MOUSE, which is a leftover from the MPSAFE
>>> TTY
>>>   import.
>> This might help mouse interactivity for desktop users that have legacy
>> Giant-locked systems in use (e.g. busy MSDOS filesystems, giant-locked
>> disk drivers), etc.
> Yes, but only a very very little bit. moused still delivers the input to
> /dev/consolectl, which is still Giant locked. The part where the Xorg
> server reads from /dev/sysmouse is now Giant-free.

Are you going to lock that one too? I have some problems with a sluggish PS/2
mouse when Firefox runs a heavily javascripted site (though it is way better
now that I can use nvidia(4) again without crashing).

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