• Chris Wilson's avatar
    drm/i915: Track unbound pages · 6c085a72
    Chris Wilson authored
    
    
    When dealing with a working set larger than the GATT, or even the
    mappable aperture when touching through the GTT, we end up with evicting
    objects only to rebind them at a new offset again later. Moving an
    object into and out of the GTT requires clflushing the pages, thus
    causing a double-clflush penalty for rebinding.
    
    To avoid having to clflush on rebinding, we can track the pages as they
    are evicted from the GTT and only relinquish those pages on memory
    pressure.
    
    As usual, if it were not for the handling of out-of-memory condition and
    having to manually shrink our own bo caches, it would be a net reduction
    of code. Alas.
    
    Note: The patch also contains a few changes to the last-hope
    evict_everything logic in i916_gem_execbuffer.c - we no longer try to
    only evict the purgeable stuff in a first try (since that's superflous
    and only helps in OOM corner-cases, not fragmented-gtt trashing
    situations).
    
    Also, the extraction of the get_pages retry loop from bind_to_gtt (and
    other callsites) to get_pages should imo have been a separate patch.
    
    v2: Ditch the newly added put_pages (for unbound objects only) in
    i915_gem_reset. A quick irc discussion hasn't revealed any important
    reason for this, so if we need this, I'd like to have a git blame'able
    explanation for it.
    
    v3: Undo the s/drm_malloc_ab/kmalloc/ in get_pages that Chris noticed.
    Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
    [danvet: Split out code movements and rant a bit in the commit message
    with a few Notes. Done v2]
    Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
    6c085a72
i915_gem.c 106 KB