• Huang Rui's avatar
    drm/amdgpu: use bulk moves for efficient VM LRU handling (v6) · f921661b
    Huang Rui authored
    I continue to work for bulk moving that based on the proposal by Christian.
    
    Background:
    amdgpu driver will move all PD/PT and PerVM BOs into idle list. Then move all of
    them on the end of LRU list one by one. Thus, that cause so many BOs moved to
    the end of the LRU, and impact performance seriously.
    
    Then Christian provided a workaround to not move PD/PT BOs on LRU with below
    patch:
    Commit 0bbf32026cf5ba41e9922b30e26e1bed1ecd38ae ("drm/amdgpu: band aid
    validating VM PTs")
    
    However, the final solution should bulk move all PD/PT and PerVM BOs on the LRU
    instead of one by one.
    
    Whenever amdgpu_vm_validate_pt_bos() is called and we have BOs which need to be
    validated we move all BOs together to the end of the LRU without dropping the
    lock for the LRU.
    
    While doing so we note the beginning and end of this block in the LRU list.
    
    Now when amdgpu_vm_validate_pt_bos() is called and we don't have anything to do,
    we don't move every BO one by one, but instead cut the LRU list into pieces so
    that we bulk move everything to the end in just one operation.
    
    Test data:
    +--------------+-----------------+-----------+---------------------------------------+
    |              |The Talos        |Clpeak(OCL)|BusSpeedReadback(OCL)                  |
    |              |Principle(Vulkan)|           |                                       |
    +------------------------------------------------------------------------------------+
    |              |                 |           |0.319 ms(1k) 0.314 ms(2K) 0.308 ms(4K) |
    | Original     |  147.7 FPS      |  76.86 us |0.307 ms(8K) 0.310 ms(16K)             |
    +------------------------------------------------------------------------------------+
    | Orignial + WA|                 |           |0.254 ms(1K) 0.241 ms(2K)              |
    |(don't move   |  162.1 FPS      |  42.15 us |0.230 ms(4K) 0.223 ms(8K) 0.204 ms(16K)|
    |PT BOs on LRU)|                 |           |                                       |
    +------------------------------------------------------------------------------------+
    | Bulk move    |  163.1 FPS      |  40.52 us |0.244 ms(1K) 0.252 ms(2K) 0.213 ms(4K) |
    |              |                 |           |0.214 ms(8K) 0.225 ms(16K)             |
    +--------------+-----------------+-----------+---------------------------------------+
    
    After test them with above three benchmarks include vulkan and opencl. We can
    see the visible improvement than original, and even better than original with
    workaround.
    
    v2: move all BOs include idle, relocated, and moved list to the end of LRU and
    put them together.
    v3: remove unused parameter and use list_for_each_entry instead of the one with
    save entry.
    v4: move the amdgpu_vm_move_to_lru_tail after command submission, at that time,
    all bo will be back on idle list.
    v5: remove amdgpu_vm_move_to_lru_tail_by_list(), use bulk_moveable instread of
    validated, and move ttm_bo_bulk_move_lru_tail() also into
    amdgpu_vm_move_to_lru_tail().
    v6: clean up and fix return value.
    Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
    Signed-off-by: default avatarHuang Rui <ray.huang@amd.com>
    Tested-by: default avatarMike Lothian <mike@fireburn.co.uk>
    Tested-by: default avatarDieter Nützel <Dieter@nuetzel-hh.de>
    Acked-by: default avatarChunming Zhou <david1.zhou@amd.com>
    Reviewed-by: default avatarJunwei Zhang <Jerry.Zhang@amd.com>
    Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
    f921661b
amdgpu_vm.c 75.3 KB