On 11/20/2012 07:19 AM, Dave Airlie wrote:
On Tue, Nov 6, 2012 at 9:31 PM, Thomas Hellstrom <thellstrom@xxxxxxxxxx> wrote:
The mostly used lookup+get put+potential_destroy path of TTM objects
is converted to use RCU locks. This will substantially decrease the amount
of locked bus cycles during normal operation.
Since we use kfree_rcu to free the objects, no rcu synchronization is needed
at module unload time.
As this is the first use of RCU in a drm driver from what I can see,
let me remind that the
RCU patent agreement AFAIK only covers GPL works.
So non-GPL or other OSes porting this code should take not of this.
Dave.
From VMware's side this won't be a problem, since other VMware kernel
modules (VMCI IIRC) use RCU.
In any case I have a new version of the "vmwgfx optimization" patch
series that mostly add documentation and
annotation (by using a drm_ht_xxx_rcu) interface for hashtab, after an
internal review by Dmitry Torkov. I see you've already
applied the original patch series. Do you want me to send out the new
one or rebase it against current drm-next?
Thanks,
Thomas
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