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    drm: implement helper functions for scanning lru list · 709ea971
    Daniel Vetter 提交于
    These helper functions can be used to efficiently scan lru list
    for eviction. Eviction becomes a three stage process:
    1. Scanning through the lru list until a suitable hole has been found.
    2. Scan backwards to restore drm_mm consistency and find out which
       objects fall into the hole.
    3. Evict the objects that fall into the hole.
    
    These helper functions don't allocate any memory (at the price of
    not allowing any other concurrent operations). Hence this can also be
    used for ttm (which does lru scanning under a spinlock).
    
    Evicting objects in this fashion should be more fair than the current
    approach by i915 (scan the lru for a object large enough to contain
    the new object). It's also more efficient than the current approach used
    by ttm (uncoditionally evict objects from the lru until there's enough
    free space).
    Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
    Acked-by: NThomas Hellstrom <thellstrom@vmwgfx.com>
    Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
    Signed-off-by: NDave Airlie <airlied@redhat.com>
    709ea971
drm_mm.c 15.1 KB