[Intel-gfx] [PATCH v2 1/3] drm/i915: Use the MRU stack search after evicting

[Chris Wilson]

On Wed, Jan 11, 2017 at 02:04:53PM +0200, Joonas Lahtinen wrote:
> On ke, 2017-01-11 at 11:23 +0000, Chris Wilson wrote:
> > When we evict from the GTT to make room for an object, the hole we
> > create is put onto the MRU stack inside the drm_mm range manager. On the
> > next search pass, we can speed up a PIN_HIGH allocation by referencing
> > that stack for the new hole.
> > 
> > v2: Pull together the 3 identical implements (ahem, a couple were
> > outdated) into a common routine for allocating a node and evicting as
> > necessary.
> > v3: Detect invalid calls to i915_gem_gtt_insert()
> > v4: kerneldoc
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> 
> <SNIP>
> 
> > +/**
> > + * i915_gem_gtt_insert - insert a node into an address_space (GTT)
> > + * @vm - the &struct i915_address_space
> 
> mixing &struct and @struct, I guess you meant &struct in later line
> too.
> 
> > + * @node - the @struct drm_mm_node (typicallay i915_vma.mode)
> 
> "typicallly" and "i915_vma.node"
> 
> > + * @size - how much space to allocate inside the GTT,
> > + *         must be #I915_GTT_PAGE_SIZE aligned
> > + * @alignment - required alignment of starting offset, may be 0 but
> > + *              if specified, this must be a power-of-two and at least
> > + *              #I915_GTT_MIN_ALIGNMENT
> > + * @color - color to apply to node
> > + * @start - start of any range restriction inside GTT (0 for all),
> > + *          must be #I915_GTT_PAGE_SIZE aligned
> > + * @end - end of any range restriction inside GTT (U64_MAX for all),
> > + *        must be #I915_GTT_PAGE_SIZE aligned
> > + * @flags - control search and eviction behaviour
> > + *
> > + * i915_gem_gtt_insert() first searches for an available hole into which
> > + * is can insert the node. The hole address is aligned to @alignment and
> > + * its @size must then fit entirely within the [@start, @end] bounds. The
> > + * nodes on either side of the hole must match @color, or else a guard page
> > + * will be inserted between the two nodes (or the node evicted). If no
> > + * suitable hole is found, then the LRU list of objects within the GTT
> > + * is scanned to find the first set of replacement nodes to create the hole.
> > + * Those old overlapping nodes are evicted from the GTT (and so must be
> > + * rebound before any future use). Any node that is current pinned cannot
> 
> "currently"
> 
> > + * be evicted (see i915_vma_pin()). Similar if the node's VMA is currently
> > + * active and #PIN_NONBLOCK is specified, that node is also skipped when
> > + * searching for an eviction candidate. See i915_gem_evict_something() for
> > + * the gory details on the eviction algorithm.
> > + *
> > + * Returns: 0 on success, -ENOSPC if no suitable hole is found, -EINTR if
> > + * asked to wait for eviction and interrupted.
> > + */
> 
> Fit those fixed, good to merge.

Thanks for proof reading.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre