[Intel-gfx] [RFC 0/2] Reduce the time for which 'struct_mutex' is held

[Daniel Vetter]

On Sun, May 04, 2014 at 04:48:23PM +0530, akash.goel at intel.com wrote:
> From: Akash Goel <akash.goel at intel.com>
> 
> We are trying to reduce the time for which the global 'struct_mutex'
> is locked. Execbuffer ioctl is one place where it is generally held
> for the longest time. And sometimes because of this occasional 
> glitches/flickers are being observed in 60 fps playback (due to miss of
> V-blank intervals) as page flip call is getting delayed because the
> 'struct_mutex' is already locked.

This is the point where working around our single-lock-to-rule-them-all
scheme is no longer sustainable. The first patch might be safe but
definitely scares the heck out of me, the 2nd one is definitely racy.

The right solution here is to work on per-object locking, as Chris suggest
in another mail already. This is a major task. Major = overall effort
likely exceeding man-years.

Also I need to block this on full ppgtt getting stable since we have a
hard time building castles on sands, recursing that will be unmanageble.

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch