• Pauli Nieminen's avatar
    drm/ttm: add pool wc/uc page allocator V3 · 1403b1a3
    Pauli Nieminen authored
    
    
    On AGP system we might allocate/free routinely uncached or wc memory,
    changing page from cached (wb) to uc or wc is very expensive and involves
    a lot of flushing. To improve performance this allocator use a pool
    of uc,wc pages.
    
    Pools are protected with spinlocks to allow multiple threads to allocate pages
    simultanously. Expensive operations are done outside of spinlock to maximize
    concurrency.
    
    Pools are linked lists of pages that were recently freed. mm shrink callback
    allows kernel to claim back pages when they are required for something else.
    
    Fixes:
    * set_pages_array_wb handles highmem pages so we don't have to remove them
      from pool.
    * Add count parameter to ttm_put_pages to avoid looping in free code.
    * Change looping from _safe to normal in pool fill error path.
    * Initialize sum variable and make the loop prettier in get_num_unused_pages.
    
    * Moved pages_freed reseting inside the loop in ttm_page_pool_free.
    * Add warning comment about spinlock context in ttm_page_pool_free.
    
    Based on Jerome Glisse's and Dave Airlie's pool allocator.
    Signed-off-by: default avatarJerome Glisse <jglisse@redhat.com>
    Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
    Signed-off-by: default avatarPauli Nieminen <suokkos@gmail.com>
    Reviewed-by: default avatarJerome Glisse <jglisse@redhat.com>
    Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
    1403b1a3