[Intel-gfx] [PATCH 3/3] drm/i915: Wait for the previous RCU grace period, not request completion

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-09-13 12:16:42)
> 
> On 12/09/2018 17:40, Chris Wilson wrote:
> > Under mempressure, our goal is to allow ourselves sufficient time to
> > reclaim the RCU protected slabs without overly penalizing our clients.
> > Currently, we use a 1 jiffie wait if the client is still active as a
> > means of throttling the allocations, but we can instead wait for the end
> > of the RCU grace period of the clients previous allocation.
> 
> Why did you opt for three patches changing the same code and just squash 
> to last?

1 introduced a timeout, 2 limited it to the single timeline, 3 changed
what we are waiting on entirely. Each of those are big jumps, and only
(1) is required to fix the bug.
-Chris