[Intel-gfx] [PATCH 10/17] drm/i915: Hide unshrinkable context objects from the shrinker

[Matthew Auld]

On Tue, 30 Jul 2019 at 14:31, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> The shrinker cannot touch objects used by the contexts (logical state
> and ring). Currently we mark those as "pin_global" to let the shrinker
> skip over them, however, if we remove them from the shrinker lists
> entirely, we don't event have to include them in our shrink accounting.
>
> By keeping the unshrinkable objects in our shrinker tracking, we report
> a large number of objects available to be shrunk, and leave the shrinker
> deeply unsatisfied when we fail to reclaim those. The shrinker will
> persist in trying to reclaim the unavailable objects, forcing the system
> into a livelock (not even hitting the dread oomkiller).
>
> v2: Extend unshrinkable protection for perma-pinned scratch and guc
> allocations (Tvrtko)
> v3: Notice that we should be pinned when marking unshrinkable and so the
> link cannot be empty; merge duplicate paths.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Reviewed-by: Matthew Auld <matthew.auld at intel.com>