{"id":97782,"date":"2026-08-30T08:08:44","date_gmt":"2026-08-30T00:08:44","guid":{"rendered":"https:\/\/www.wsisp.com\/helps\/97782.html"},"modified":"2026-08-30T08:08:44","modified_gmt":"2026-08-30T00:08:44","slug":"%e7%ac%ac%e4%ba%94%e7%ab%a0%ef%bc%9abo%e7%9a%84%e5%85%b1%e4%ba%ab%ef%bc%9a5-2-5-dynamic-dma-buf%ef%bc%9a%e5%85%b1%e4%ba%ab%e4%b8%8b%e7%9a%84%e8%bf%81%e7%a7%bb","status":"publish","type":"post","link":"https:\/\/www.wsisp.com\/helps\/97782.html","title":{"rendered":"\u7b2c\u4e94\u7ae0\uff1aBO\u7684\u5171\u4eab\uff1a5.2.5 dynamic dma-buf\uff1a\u5171\u4eab\u4e0b\u7684\u8fc1\u79fb"},"content":{"rendered":"

5.2.4 \u7ed3\u5c3e\u7559\u4e0b\u4e86\u4e00\u4e2a\u60ac\u5ff5：\u5bfc\u5165\u65b9\u901a\u8fc7 dma_buf_attach \u2192 dma_buf_map_attachment \u62ff\u5230 sg_table \u4e4b\u540e，\u8fd9\u5f20\u8868\u91cc\u7684 DMA \u5730\u5740\u5c31\u56fa\u5b9a\u6307\u5411\u4e86 buffer \u5f53\u524d\u6240\u5728\u7684\u7269\u7406\u4f4d\u7f6e\u3002\u53ef\u5982\u679c\u5bfc\u51fa\u65b9\u662f GPU，\u5b83\u7684\u663e\u5b58\u968f\u65f6\u53ef\u80fd\u56e0\u4e3a TTM eviction\u3001\u663e\u5b58\u5403\u7d27\u800c\u628a\u8fd9\u5757 BO \u4ece VRAM \u642c\u5230 GTT\u3001\u751a\u81f3\u6362\u51fa\u3002\u4e00\u65e6 buffer \u642c\u4e86\u5bb6，\u5bfc\u5165\u65b9\u624b\u91cc\u90a3\u5f20\u65e7 sg_table \u5c31\u53d8\u6210\u4e86\u6307\u5411\u9519\u8bef\u4f4d\u7f6e\u7684\u300c\u91ce\u5730\u5740\u300d\u3002<\/p>\n

\u300c\u9759\u6001\u5bfc\u5165\u65b9\u300d\u7684\u89e3\u6cd5\u7b80\u5355\u7c97\u66b4：map \u65f6 pin \u4f4f\u540e\u7aef\u5b58\u50a8，\u6620\u5c04\u5b58\u5728\u671f\u95f4\u8c01\u4e5f\u522b\u60f3\u52a8\u5b83\u3002\u4ee3\u4ef7\u662f\u663e\u5b58\u88ab\u957f\u671fpin\u4f4f\u2014\u2014\u4e00\u5757\u88ab RDMA \u7f51\u5361\u6620\u5c04\u8d70\u7684 GPU BO，\u54ea\u6015 GPU \u81ea\u5df1\u663e\u5b58\u544a\u6025\u4e5f\u65e0\u6cd5\u8fc1\u79fb\u6216\u6362\u51fa\u3002\u5bf9\u6e32\u67d3\u3001AI \u8fd9\u7c7b\u8981\u53cd\u590d\u5171\u4eab\u5927\u91cf buffer \u7684\u573a\u666f，\u8fd9\u79cd\u300c\u9489\u6b7b\u300d\u662f\u4e0d\u53ef\u63a5\u53d7\u7684\u3002<\/p>\n

Dynamic dma-buf（\u52a8\u6001 dma-buf） \u5c31\u662f\u4e3a\u5316\u89e3\u8fd9\u5bf9\u77db\u76fe\u800c\u751f：\u5bfc\u5165\u65b9\u4e0d\u518d\u8981\u6c42 pin，\u800c\u662f\u5411\u5bfc\u51fa\u65b9\u6ce8\u518c\u4e00\u4e2a move_notify \u56de\u8c03；\u5bfc\u51fa\u65b9\u6bcf\u6b21\u8981\u642c\u52a8 buffer \u524d，\u5148\u9010\u4e2a\u901a\u77e5\u6240\u6709\u52a8\u6001\u5bfc\u5165\u65b9\u300c\u6211\u8981\u52a8\u4e86，\u8bf7\u628a\u4f60\u7684\u65e7\u6620\u5c04\u4f5c\u5e9f\u3001\u7a0d\u540e\u91cd\u5efa\u300d\u3002\u4e8e\u662f\u663e\u5b58\u91cd\u65b0\u53d8\u5f97\u53ef\u8fc1\u79fb，\u5171\u4eab\u4e5f\u4e0d\u518d\u4ee5pin\u4e3a\u4ee3\u4ef7\u3002<\/p>\n

1. \u9759\u6001 vs \u52a8\u6001<\/h3>\n

\u56de\u987e 5.2.4：\u5bfc\u5165\u65b9\u662f\u5426\u300c\u52a8\u6001\u300d，\u5b8c\u5168\u53d6\u51b3\u4e8e dma_buf_dynamic_attach() \u65f6\u4f20\u5165\u7684 importer_ops \u662f\u5426\u4e3a NULL\u3002<\/p>\n

struct<\/span> dma_buf_attachment<\/span> *<\/span>dma_buf_attach<\/span>(<\/span>struct<\/span> dma_buf<\/span> *<\/span>dmabuf,<\/span>
\n struct<\/span> device<\/span> *<\/span>dev)<\/span>
\n{<\/span>
\n return<\/span> dma_buf_dynamic_attach<\/span>(<\/span>dmabuf,<\/span> dev,<\/span> NULL<\/span>,<\/span> NULL<\/span>)<\/span>;<\/span> \/* \u9759\u6001：importer_ops = NULL *\/<\/span>
\n}<\/span><\/p>\n

\u4f20\u5165\u975e NULL \u7684 importer_ops（\u5176\u4e2d\u5e26 move_notify），\u5c31\u6210\u4e86\u52a8\u6001\u5bfc\u5165\u65b9\u3002\u4e8c\u8005\u7684\u884c\u4e3a\u5dee\u5f02\u53ef\u4ee5\u6d53\u7f29\u6210\u4e00\u5f20\u8868：<\/p>\n\n\u9759\u6001\u5bfc\u5165\u65b9（importer_ops == NULL）\u52a8\u6001\u5bfc\u5165\u65b9（importer_ops != NULL）<\/tr>\n\n\n\n\n\n\n\n
\u5224\u5b9a\u51fd\u6570<\/td>\ndma_buf_attachment_is_dynamic() = false<\/td>\n= true<\/td>\n<\/tr>\n
map \u65f6\u662f\u5426 pin \u540e\u7aef<\/td>\n\u662f（pin_on_map \u6210\u7acb）<\/td>\n\u5426<\/td>\n<\/tr>\n
buffer \u53ef\u5426\u88ab\u8fc1\u79fb<\/td>\n\u6620\u5c04\u671f\u95f4\u4e0d\u53ef<\/td>\n\u53ef\u2014\u2014\u8fc1\u79fb\u524d\u7ecf move_notify \u901a\u77e5<\/td>\n<\/tr>\n
\u8fc1\u79fb\u540e\u65e7 sg_table<\/td>\n\u4e0d\u5b58\u5728\u6b64\u95ee\u9898<\/td>\n\u7acb\u5373\u5931\u6548，\u987b\u91cd\u65b0 map<\/td>\n<\/tr>\n
\u540c\u6b65\u8d23\u4efb<\/td>\ncore \u5e2e\u5fd9\u7b49 KERNEL fence<\/td>\n\u5bfc\u5165\u65b9\u81ea\u5df1\u9075\u5b88 write fence<\/td>\n<\/tr>\n
\u5178\u578b\u4f7f\u7528\u8005<\/td>\n\u7b80\u5355 scanout\u3001\u4e0d\u652f\u6301 ODP \u7684 RDMA<\/td>\nGPU\u2194GPU \u4e92\u5bfc\u3001\u652f\u6301 move \u7684\u73b0\u4ee3\u9a71\u52a8<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\u4e00\u53e5\u8bdd：\u9759\u6001\u7528\u300cpin \u4f4f\u4e0d\u8bb8\u52a8\u300d\u6362\u7b80\u5355，\u52a8\u6001\u7528\u300c\u968f\u65f6\u51c6\u5907\u91cd\u6620\u5c04\u300d\u6362\u663e\u5b58\u4e0d\u88ab pin\u3002<\/p>\n

2. move_notify：\u52a8\u6001\u673a\u5236\u7684\u5fc3\u810f<\/h3>\n

\u52a8\u6001\u673a\u5236\u7684\u5168\u90e8\u7cbe\u9ad3，\u5c31\u5728\u5bfc\u51fa\u65b9\u642c\u79fb buffer \u524d\u8c03\u7528\u7684\u8fd9\u4e00\u4e2a\u51fd\u6570：<\/p>\n

void<\/span> dma_buf_move_notify<\/span>(<\/span>struct<\/span> dma_buf<\/span> *<\/span>dmabuf)<\/span>
\n{<\/span>
\n struct<\/span> dma_buf_attachment<\/span> *<\/span>attach;<\/span><\/p>\n

dma_resv_assert_held<\/span>(<\/span>dmabuf-><\/span>resv)<\/span>;<\/span><\/p>\n

list_for_each_entry<\/span>(<\/span>attach,<\/span> &<\/span>dmabuf-><\/span>attachments,<\/span> node)<\/span>
\n if<\/span> (<\/span>attach-><\/span>importer_ops)<\/span>
\n attach-><\/span>importer_ops-><\/span>move_notify<\/span>(<\/span>attach)<\/span>;<\/span>
\n}<\/span><\/p>\n

  • \u904d\u5386 dmabuf->attachments \u94fe\u8868：\u5bfc\u51fa\u65b9\u65e0\u9700\u77e5\u9053\u5bf9\u7aef\u662f\u8c01，\u7167\u7740\u94fe\u8868\u9010\u4e2a\u901a\u77e5\u5373\u53ef\u3002<\/li>\n
  • \u53ea\u901a\u77e5\u52a8\u6001\u5bfc\u5165\u65b9（if (attach->importer_ops)）：\u9759\u6001\u5bfc\u5165\u65b9\u6ca1\u6709 move_notify，\u4e5f\u4e0d\u9700\u8981\u2014\u2014\u5b83\u4eec\u7684 buffer \u672c\u5c31\u88ab pin \u4f4f\u4e0d\u4f1a\u79fb\u52a8\u3002<\/li>\n
  • \u5fc5\u987b\u5728\u6301 resv \u9501\u65f6\u8c03\u7528（dma_resv_assert_held）：\u8fd9\u4fdd\u8bc1\u4e86\u300c\u901a\u77e5\u5bfc\u5165\u65b9\u300d\u4e0e\u300c\u5b9e\u9645\u642c\u79fb\u300d\u4e4b\u95f4\u4e0d\u4f1a\u6709\u5e76\u53d1\u7684\u65b0\u6620\u5c04\u63d2\u8fdb\u6765\u3002\u56de\u8c03\u672c\u8eab\u4e5f\u5728\u6301\u9501\u72b6\u6001\u4e0b\u6267\u884c\u3002<\/li>\n

    struct dma_buf_attach_ops \u7684\u5b9a\u4e49\u5370\u8bc1\u4e86\u8fd9\u5957\u5951\u7ea6：<\/p>\n

    struct<\/span> dma_buf_attach_ops<\/span> {<\/span>
    \n bool allow_peer2peer;<\/span> \/* \u5bfc\u5165\u65b9\u80fd\u5426\u5904\u7406\u65e0 struct page \u7684\u5bf9\u7aef\u8d44\u6e90 *\/<\/span>
    \n void<\/span> (<\/span>*<\/span>move_notify)<\/span>(<\/span>struct<\/span> dma_buf_attachment<\/span> *<\/span>attach)<\/span>;<\/span> \/* [\u53ef\u9009] buffer \u6b63\u5728\u79fb\u52a8 *\/<\/span>
    \n}<\/span>;<\/span><\/p>\n

    \u5185\u6838\u5934\u6587\u4ef6\u5bf9 move_notify \u7684\u8bed\u4e49\u6709\u6781\u7cbe\u786e\u7684\u63cf\u8ff0，\u503c\u5f97\u9010\u6761\u62c6\u89e3：<\/p>\n

      \n
    • \u201cMappings stay valid and are not directly affected by this callback\u201d\u2014\u2014\u56de\u8c03\u89e6\u53d1\u7684\u77ac\u95f4，\u65e7\u6620\u5c04\u5728\u7269\u7406\u4e0a\u4ecd\u7136\u6709\u6548，move_notify \u53ea\u662f\u4e00\u4e2a\u300c\u9884\u8b66\u300d，\u4e0d\u662f\u300c\u5df2\u7ecf\u642c\u5b8c\u300d\u3002<\/li>\n
    • \u201cBut the DMA-buf can now be in a different physical location, so all mappings should be destroyed and re-created as soon as possible\u201d\u2014\u2014\u5bfc\u5165\u65b9\u6536\u5230\u901a\u77e5\u540e，\u5e94\u5c3d\u5feb\u4f5c\u5e9f\u65e7 sg_table \u5e76\u5728\u4e0b\u6b21\u4f7f\u7528\u524d\u91cd\u5efa\u3002<\/li>\n
    • \u201cNew mappings can be created after this callback returns, and will point to the new location\u201d\u2014\u2014\u56de\u8c03\u8fd4\u56de\u540e\u65b0\u5efa\u7684\u6620\u5c04，\u6307\u5411\u7684\u5c31\u662f\u642c\u79fb\u540e\u7684\u65b0\u4f4d\u7f6e\u3002<\/li>\n<\/ul>\n

      3. pin \/ unpin：\u52a8\u6001\u5bfc\u5165\u65b9\u7684\u300c\u4e34\u65f6\u9489\u4f4f\u300d<\/h3>\n

      \u52a8\u6001\u673a\u5236\u5e76\u975e\u5b8c\u5168\u5426\u5b9a pin，\u800c\u662f\u628a pin \u4ece\u300cmap \u65f6\u5f3a\u5236\u300d\u964d\u7ea7\u4e3a\u300c\u6309\u9700\u4e34\u65f6\u300d\u3002dma_buf_pin() \/ dma_buf_unpin() \u4e13\u4f9b\u52a8\u6001\u5bfc\u5165\u65b9\u5728\u786e\u5b9e\u9700\u8981\u4e00\u6bb5\u7a33\u5b9a\u7269\u7406\u5730\u5740（\u5982\u628a buffer \u62ff\u53bb\u505a scanout \u4e0a\u5c4f）\u65f6\u4f7f\u7528：<\/p>\n

      int<\/span> dma_buf_pin<\/span>(<\/span>struct<\/span> dma_buf_attachment<\/span> *<\/span>attach)<\/span>
      \n{<\/span>
      \n struct<\/span> dma_buf<\/span> *<\/span>dmabuf =<\/span> attach-><\/span>dmabuf;<\/span>
      \n int<\/span> ret =<\/span> 0<\/span>;<\/span><\/p>\n

      WARN_ON<\/span>(<\/span>!<\/span>attach-><\/span>importer_ops)<\/span>;<\/span> \/* \u53ea\u6709\u52a8\u6001\u5bfc\u5165\u65b9\u80fd\u8c03\u7528 *\/<\/span>
      \n dma_resv_assert_held<\/span>(<\/span>dmabuf-><\/span>resv)<\/span>;<\/span><\/p>\n

      if<\/span> (<\/span>dmabuf-><\/span>ops-><\/span>pin)<\/span>
      \n ret =<\/span> dmabuf-><\/span>ops-><\/span>pin<\/span>(<\/span>attach)<\/span>;<\/span>
      \n return<\/span> ret;<\/span>
      \n}<\/span><\/p>\n

      void<\/span> dma_buf_unpin<\/span>(<\/span>struct<\/span> dma_buf_attachment<\/span> *<\/span>attach)<\/span>
      \n{<\/span>
      \n struct<\/span> dma_buf<\/span> *<\/span>dmabuf =<\/span> attach-><\/span>dmabuf;<\/span><\/p>\n

      WARN_ON<\/span>(<\/span>!<\/span>attach-><\/span>importer_ops)<\/span>;<\/span>
      \n dma_resv_assert_held<\/span>(<\/span>dmabuf-><\/span>resv)<\/span>;<\/span><\/p>\n

      if<\/span> (<\/span>dmabuf-><\/span>ops-><\/span>unpin)<\/span>
      \n dmabuf-><\/span>ops-><\/span>unpin<\/span>(<\/span>attach)<\/span>;<\/span>
      \n}<\/span><\/p>\n

      \u4e09\u4e2a\u7ea6\u675f\u503c\u5f97\u7559\u610f：<\/p>\n

    • WARN_ON(!attach->importer_ops)：\u8fd9\u4e24\u4e2a API \u53ea\u5141\u8bb8\u52a8\u6001\u5bfc\u5165\u65b9\u8c03\u7528\u3002\u9759\u6001\u5bfc\u5165\u65b9\u7684 pin \u662f\u5728 map \u5185\u90e8\u81ea\u52a8\u5b8c\u6210\u7684（5.2.4 \u7684 dma_buf_pin_on_map），\u4e0d\u8d70\u8fd9\u6761\u8def\u3002<\/li>\n
    • \u5185\u6838\u6ce8\u91ca\u660e\u786e\u9650\u5236\u7528\u9014：dma_buf_pin \u7684\u6ce8\u91ca\u5199\u9053\u300conly for limited use cases like scanout and not for temporary pin operations\u300d\u300c\u4e0d\u5f97\u8ba9\u7528\u6237\u6001\u901a\u8fc7\u6b64\u63a5\u53e3 pin \u4f4f\u4efb\u610f\u6570\u91cf\u7684 buffer\u300d\u2014\u2014\u9632\u6b62\u52a8\u6001\u673a\u5236\u88ab\u6ee5\u7528\u6210\u53d8\u76f8\u7684\u300c\u65e0\u9650\u9489\u6b7b\u300d\u3002<\/li>\n
    • unpin \u4e4b\u540e buffer \u91cd\u65b0\u53ef\u8fc1\u79fb：\u6ce8\u91ca\u70b9\u660e unpin\u300callows the exporter to move any mapping of @attach again and inform the importer through move_notify\u300d\u2014\u2014\u5373 unpin \u8ba9 buffer \u56de\u5230\u300c\u53ef\u642c\u79fb\u3001\u642c\u79fb\u65f6\u53d1 move_notify\u300d\u7684\u5e38\u6001\u3002<\/li>\n

      \u4e8e\u662f\u4e09\u8005\u6784\u6210\u4e00\u4e2a\u6e05\u6670\u7684\u5c42\u6b21：move_notify \u662f\u5e38\u6001（\u53ef\u8fc1\u79fb），pin\/unpin \u662f\u4e34\u65f6\u7684\u4f8b\u5916（\u77ed\u6682\u9489\u4f4f\u505a scanout），\u9759\u6001\u5bfc\u5165\u65b9\u7684 map \u65f6 pin \u624d\u662f\u6c38\u4e45\u9489\u6b7b\u3002<\/p>\n

      4. amdgpu \u5b9e\u6218：move_notify \u91cc\u5230\u5e95\u505a\u4e86\u4ec0\u4e48<\/h3>\n

      \u62bd\u8c61\u8bb2\u5b8c，\u843d\u5230 amdgpu \u770b GPU \u9a71\u52a8\u5982\u4f55\u5b9e\u73b0\u8fd9\u5957\u5951\u7ea6\u3002amdgpu \u4f5c\u4e3a\u52a8\u6001\u5bfc\u5165\u65b9\u65f6\u6ce8\u518c\u7684\u56de\u8c03\u8868\u662f：<\/p>\n

      static<\/span> const<\/span> struct<\/span> dma_buf_attach_ops<\/span> amdgpu_dma_buf_attach_ops =<\/span> {<\/span>
      \n .<\/span>allow_peer2peer =<\/span> true,<\/span>
      \n .<\/span>move_notify =<\/span> amdgpu_dma_buf_move_notify
      \n}<\/span>;<\/span><\/p>\n

      allow_peer2peer = true \u8868\u793a amdgpu \u80fd\u5904\u7406\u300c\u5bf9\u7aef VRAM \u76f4\u8fde（P2P）\u3001\u6ca1\u6709 struct page\u300d\u7684\u8d44\u6e90\u2014\u2014\u8fd9\u4e5f\u662f\u5b83\u5728 attach \u65f6\u534f\u5546 P2P \u80fd\u529b\u7684\u524d\u63d0\u3002\u6838\u5fc3\u662f move_notify \u7684\u5b9e\u73b0：<\/p>\n

      static<\/span> void<\/span>
      \namdgpu_dma_buf_move_notify<\/span>(<\/span>struct<\/span> dma_buf_attachment<\/span> *<\/span>attach)<\/span>
      \n{<\/span>
      \n struct<\/span> drm_gem_object<\/span> *<\/span>obj =<\/span> attach-><\/span>importer_priv;<\/span>
      \n struct<\/span> amdgpu_bo<\/span> *<\/span>bo =<\/span> gem_to_amdgpu_bo<\/span>(<\/span>obj)<\/span>;<\/span>
      \n struct<\/span> ttm_operation_ctx<\/span> ctx =<\/span> {<\/span> false,<\/span> false }<\/span>;<\/span>
      \n struct<\/span> ttm_placement<\/span> placement =<\/span> {<\/span>}<\/span>;<\/span>
      \n struct<\/span> amdgpu_vm_bo_base<\/span> *<\/span>bo_base;<\/span>
      \n int<\/span> r;<\/span><\/p>\n

      \/* 1. \u8ba9\u672c\u5730\u8fd9\u5757\u300c\u5bfc\u5165 BO\u300d\u5931\u6548 *\/<\/span>
      \n amdgpu_vm_bo_invalidate<\/span>(<\/span>bo,<\/span> false)<\/span>;<\/span>
      \n if<\/span> (<\/span>!<\/span>bo-><\/span>tbo.<\/span>resource ||<\/span> bo-><\/span>tbo.<\/span>resource-><\/span>mem_type ==<\/span> TTM_PL_SYSTEM)<\/span>
      \n return<\/span>;<\/span><\/p>\n

      \/* 2. \u7528\u7a7a placement \u6821\u9a8c：\u628a\u5b83\u8e22\u56de SYSTEM，\u5373\u4f5c\u5e9f\u65e7\u7684\u7269\u7406\u6620\u5c04 *\/<\/span>
      \n r =<\/span> ttm_bo_validate<\/span>(<\/span>&<\/span>bo-><\/span>tbo,<\/span> &<\/span>placement,<\/span> &<\/span>ctx)<\/span>;<\/span>
      \n .<\/span>.<\/span>.<\/span><\/p>\n

      \/* 3. \u904d\u5386\u6240\u6709\u628a\u8be5 BO \u6620\u5c04\u8fdb GPU \u865a\u62df\u5730\u5740\u7a7a\u95f4\u7684 VM，\u66f4\u65b0\u9875\u8868 *\/<\/span>
      \n for<\/span> (<\/span>bo_base =<\/span> bo-><\/span>vm_bo;<\/span> bo_base;<\/span> bo_base =<\/span> bo_base-><\/span>next)<\/span> {<\/span>
      \n struct<\/span> amdgpu_vm<\/span> *<\/span>vm =<\/span> bo_base-><\/span>vm;<\/span>
      \n struct<\/span> dma_resv<\/span> *<\/span>resv =<\/span> vm-><\/span>root.<\/span>bo-><\/span>tbo.<\/span>base.<\/span>resv;<\/span>
      \n .<\/span>.<\/span>.<\/span>
      \n r =<\/span> amdgpu_vm_handle_moved<\/span>(<\/span>adev,<\/span> vm,<\/span> NULL<\/span>)<\/span>;<\/span> \/* \u91cd\u5efa GPU \u9875\u8868\u6620\u5c04 *\/<\/span>
      \n .<\/span>.<\/span>.<\/span>
      \n }<\/span>
      \n}<\/span><\/p>\n

      \u5bf9\u7167\u7b2c 2 \u8282\u7684\u5934\u6587\u4ef6\u8bed\u4e49，\u8fd9\u6bb5\u4ee3\u7801\u628a\u300c\u4f5c\u5e9f + \u91cd\u5efa\u300d\u843d\u5230\u4e86\u5b9e\u5904：<\/p>\n

        \n
      • amdgpu_vm_bo_invalidate + \u7a7a placement \u7684 ttm_bo_validate：\u628a\u8fd9\u5757\u5bfc\u5165 BO \u7684\u65e7\u6620\u5c04\u4f5c\u5e9f（\u63a8\u56de SYSTEM \u57df）\u3002\u8fd9\u6b63\u662f\u54cd\u5e94\u300cbuffer \u6362\u4e86\u7269\u7406\u4f4d\u7f6e，\u65e7\u6620\u5c04\u8981\u9500\u6bc1\u300d\u3002<\/li>\n
      • \u904d\u5386 bo->vm_bo \u66f4\u65b0 GPU \u9875\u8868：amdgpu \u4e0d\u53ea\u662f\u4f5c\u5e9f CPU\/DMA \u4fa7\u7684 sg_table，\u5b83\u628a\u300cBO \u5df2\u79fb\u52a8\u300d\u7684\u4e8b\u5b9e\u4e00\u8def\u4f20\u5bfc\u5230\u81ea\u5df1\u7684 GPUVM \u9875\u8868\u2014\u2014\u6240\u6709\u5f15\u7528\u8fd9\u5757 BO \u7684 GPU \u865a\u62df\u5730\u5740\u6620\u5c04\u90fd\u8981\u8ddf\u7740\u66f4\u65b0\u3002\u8fd9\u4e00\u6b65\u547c\u5e94\u4e86\u7b2c\u4e5d\u7ae0 GPUVM \u7684 amdgpu_vm_handle_moved\u3002<\/li>\n
      • \u5168\u7a0b\u5728\u6301\u9501\u4e0b\u64cd\u4f5c VM \u7684 resv：\u4e0e dma_buf_move_notify \u6301 dmabuf->resv \u9501\u7684\u7ea6\u5b9a\u4e00\u8109\u76f8\u627f，\u907f\u514d\u4e0e\u547d\u4ee4\u63d0\u4ea4\u5e76\u53d1\u3002<\/li>\n<\/ul>\n

        \u800c amdgpu \u4f5c\u4e3a\u5bfc\u51fa\u65b9\u65f6\u7684 pin\/unpin（amdgpu_dma_buf_pin \/ amdgpu_dma_buf_unpin）\u5219\u5c55\u793a\u4e86 move_notify \u80fd\u529b\u5982\u4f55\u53cd\u5411\u5f71\u54cd pin \u7b56\u7565：<\/p>\n

        static<\/span> int<\/span> amdgpu_dma_buf_pin<\/span>(<\/span>struct<\/span> dma_buf_attachment<\/span> *<\/span>attach)<\/span>
        \n{<\/span>
        \n struct<\/span> amdgpu_bo<\/span> *<\/span>bo =<\/span> gem_to_amdgpu_bo<\/span>(<\/span>attach-><\/span>dmabuf-><\/span>priv)<\/span>;<\/span>
        \n u32 domains =<\/span> bo-><\/span>allowed_domains;<\/span><\/p>\n

        \/* \u53ea\u6709\u5f00\u542f move_notify \u65f6，\u624d\u5141\u8bb8 pin \u8fdb VRAM \u505a P2P；
        \n * \u5426\u5219\u9000\u56de GTT，\u907f\u514d GPU \u4e0e RDMA \u5728\u65e0 move \u901a\u77e5\u65f6\u7684\u9489\u6b7b\u51b2\u7a81 *\/<\/span>
        \n if<\/span> (<\/span>!<\/span>IS_ENABLED<\/span>(<\/span>CONFIG_DMABUF_MOVE_NOTIFY)<\/span>)<\/span> {<\/span>
        \n domains &=<\/span> ~<\/span>AMDGPU_GEM_DOMAIN_VRAM;<\/span>
        \n }<\/span> else<\/span> {<\/span>
        \n list_for_each_entry<\/span>(<\/span>attach,<\/span> &<\/span>dmabuf-><\/span>attachments,<\/span> node)<\/span>
        \n if<\/span> (<\/span>!<\/span>attach-><\/span>peer2peer)<\/span>
        \n domains &=<\/span> ~<\/span>AMDGPU_GEM_DOMAIN_VRAM;<\/span>
        \n }<\/span>
        \n .<\/span>.<\/span>.<\/span>
        \n return<\/span> amdgpu_bo_pin<\/span>(<\/span>bo,<\/span> domains)<\/span>;<\/span>
        \n}<\/span><\/p>\n

        \u8fd9\u6bb5\u903b\u8f91\u7684\u5224\u65ad\u6781\u5177\u4ee3\u8868\u6027：\u53ea\u6709\u5728\u7f16\u8bd1\u5f00\u542f CONFIG_DMABUF_MOVE_NOTIFY（\u5373\u52a8\u6001\u673a\u5236\u53ef\u7528）\u65f6，amdgpu \u624d\u6562\u628a buffer pin \u8fdb VRAM \u4f9b\u5bf9\u7aef P2P \u76f4\u8fde；\u5426\u5219\u4e00\u5f8b\u9000\u56de GTT（\u7cfb\u7edf\u5185\u5b58）\u4e2d\u8f6c\u3002\u539f\u56e0\u6b63\u662f\u6ce8\u91ca\u6240\u8bf4\u2014\u2014\u6ca1\u6709 move \u901a\u77e5\u65f6，\u4e00\u65e6 pin \u8fdb VRAM \u5c31\u53ef\u80fd\u4e0e RDMA \u4ea7\u751f\u300c\u8c01\u4e5f\u4e0d\u80fd\u52a8\u300d\u7684\u9489\u6b7b\u51b2\u7a81\u3002<\/p>\n

        5. \u4e00\u6b21\u5b8c\u6574\u7684\u52a8\u6001\u642c\u79fb\u65f6\u5e8f<\/h3>\n

        \u628a\u4e0a\u8ff0\u73af\u8282\u4e32\u6210\u4e00\u6761\u65f6\u95f4\u7ebf，\u52a8\u6001 dma-buf \u7684\u4ef7\u503c\u5c31\u4e00\u76ee\u4e86\u7136：<\/p>\n

        \u52a8\u6001\u5bfc\u5165\u65b9（\u53e6\u4e00 GPU \/ \u7f51\u5361）<\/p>\n

        dma-buf core<\/p>\n

        \u5bfc\u51fa\u65b9 GPU（TTM）<\/p>\n

        \u52a8\u6001\u5bfc\u5165\u65b9（\u53e6\u4e00 GPU \/ \u7f51\u5361）<\/p>\n

        dma-buf core<\/p>\n

        \u5bfc\u51fa\u65b9 GPU（TTM）<\/p>\n

        #mermaid-svg-lyRWMiM57OJZS8cn{font-family:\\”trebuchet ms\\”,verdana,arial,sans-serif;font-size:16px;fill:#333;}@keyframes edge-animation-frame{from{stroke-dashoffset:0;}}@keyframes dash{to{stroke-dashoffset:0;}}#mermaid-svg-lyRWMiM57OJZS8cn .edge-animation-slow{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 50s linear infinite;stroke-linecap:round;}#mermaid-svg-lyRWMiM57OJZS8cn .edge-animation-fast{stroke-dasharray:9,5!important;stroke-dashoffset:900;animation:dash 20s linear infinite;stroke-linecap:round;}#mermaid-svg-lyRWMiM57OJZS8cn .error-icon{fill:#552222;}#mermaid-svg-lyRWMiM57OJZS8cn .error-text{fill:#552222;stroke:#552222;}#mermaid-svg-lyRWMiM57OJZS8cn .edge-thickness-normal{stroke-width:1px;}#mermaid-svg-lyRWMiM57OJZS8cn .edge-thickness-thick{stroke-width:3.5px;}#mermaid-svg-lyRWMiM57OJZS8cn .edge-pattern-solid{stroke-dasharray:0;}#mermaid-svg-lyRWMiM57OJZS8cn .edge-thickness-invisible{stroke-width:0;fill:none;}#mermaid-svg-lyRWMiM57OJZS8cn .edge-pattern-dashed{stroke-dasharray:3;}#mermaid-svg-lyRWMiM57OJZS8cn .edge-pattern-dotted{stroke-dasharray:2;}#mermaid-svg-lyRWMiM57OJZS8cn .marker{fill:#333333;stroke:#333333;}#mermaid-svg-lyRWMiM57OJZS8cn .marker.cross{stroke:#333333;}#mermaid-svg-lyRWMiM57OJZS8cn svg{font-family:\\”trebuchet ms\\”,verdana,arial,sans-serif;font-size:16px;}#mermaid-svg-lyRWMiM57OJZS8cn p{margin:0;}#mermaid-svg-lyRWMiM57OJZS8cn .actor{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-lyRWMiM57OJZS8cn text.actor>tspan{fill:black;stroke:none;}#mermaid-svg-lyRWMiM57OJZS8cn .actor-line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);}#mermaid-svg-lyRWMiM57OJZS8cn .innerArc{stroke-width:1.5;stroke-dasharray:none;}#mermaid-svg-lyRWMiM57OJZS8cn .messageLine0{stroke-width:1.5;stroke-dasharray:none;stroke:#333;}#mermaid-svg-lyRWMiM57OJZS8cn .messageLine1{stroke-width:1.5;stroke-dasharray:2,2;stroke:#333;}#mermaid-svg-lyRWMiM57OJZS8cn #arrowhead path{fill:#333;stroke:#333;}#mermaid-svg-lyRWMiM57OJZS8cn .sequenceNumber{fill:white;}#mermaid-svg-lyRWMiM57OJZS8cn #sequencenumber{fill:#333;}#mermaid-svg-lyRWMiM57OJZS8cn #crosshead path{fill:#333;stroke:#333;}#mermaid-svg-lyRWMiM57OJZS8cn .messageText{fill:#333;stroke:none;}#mermaid-svg-lyRWMiM57OJZS8cn .labelBox{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-lyRWMiM57OJZS8cn .labelText,#mermaid-svg-lyRWMiM57OJZS8cn .labelText>tspan{fill:black;stroke:none;}#mermaid-svg-lyRWMiM57OJZS8cn .loopText,#mermaid-svg-lyRWMiM57OJZS8cn .loopText>tspan{fill:black;stroke:none;}#mermaid-svg-lyRWMiM57OJZS8cn .loopLine{stroke-width:2px;stroke-dasharray:2,2;stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);}#mermaid-svg-lyRWMiM57OJZS8cn .note{stroke:#aaaa33;fill:#fff5ad;}#mermaid-svg-lyRWMiM57OJZS8cn .noteText,#mermaid-svg-lyRWMiM57OJZS8cn .noteText>tspan{fill:black;stroke:none;}#mermaid-svg-lyRWMiM57OJZS8cn .activation0{fill:#f4f4f4;stroke:#666;}#mermaid-svg-lyRWMiM57OJZS8cn .activation1{fill:#f4f4f4;stroke:#666;}#mermaid-svg-lyRWMiM57OJZS8cn .activation2{fill:#f4f4f4;stroke:#666;}#mermaid-svg-lyRWMiM57OJZS8cn .actorPopupMenu{position:absolute;}#mermaid-svg-lyRWMiM57OJZS8cn .actorPopupMenuPanel{position:absolute;fill:#ECECFF;box-shadow:0px 8px 16px 0px rgba(0,0,0,0.2);filter:drop-shadow(3px 5px 2px rgb(0 0 0 \/ 0.4));}#mermaid-svg-lyRWMiM57OJZS8cn .actor-man line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;}#mermaid-svg-lyRWMiM57OJZS8cn .actor-man circle,#mermaid-svg-lyRWMiM57OJZS8cn line{stroke:hsl(259.6261682243, 59.7765363128%, 87.9019607843%);fill:#ECECFF;stroke-width:2px;}#mermaid-svg-lyRWMiM57OJZS8cn :root{–mermaid-font-family:\\”trebuchet ms\\”,verdana,arial,sans-serif;}<\/p>\n

        \u5bfc\u5165\u9636\u6bb5（\u4e0d pin）<\/p>\n

        \u7528 sg_table \u9a71\u52a8 DMA，buffer \u4ecd\u53ef\u8fc1\u79fb<\/p>\n

        \u663e\u5b58\u544a\u6025，TTM \u51b3\u5b9a\u628a\u8fd9\u5757 BO \u4ece VRAM \u642c\u5230 GTT<\/p>\n

        \u4e0b\u6b21\u8981\u7528\u65f6\u91cd\u65b0\u6620\u5c04<\/p>\n

        dma_buf_dynamic_attach(dmabuf, dev, importer_ops)<\/p>\n

        1<\/p>\n

        dma_buf_map_attachment() \u2192 sg_table（\u6307\u5411 VRAM）<\/p>\n

        2<\/p>\n

        dma_resv_lock(dmabuf->>resv)<\/p>\n

        3<\/p>\n

        dma_buf_move_notify(dmabuf)<\/p>\n

        4<\/p>\n

        importer_ops->>move_notify(attach)<\/p>\n

        5<\/p>\n

        \u4f5c\u5e9f\u65e7 sg_table \/ \u66f4\u65b0\u81ea\u8eab\u9875\u8868<\/p>\n

        6<\/p>\n

        \u771f\u6b63\u642c\u79fb buffer（VRAM \u2192 GTT）<\/p>\n

        7<\/p>\n

        dma_resv_unlock()<\/p>\n

        8<\/p>\n

        dma_buf_map_attachment() \u2192 \u65b0 sg_table（\u6307\u5411 GTT）<\/p>\n

        9<\/p>\n

        \u5bf9\u6bd4\u9759\u6001\u8def\u5f84\u2014\u2014\u9759\u6001\u5bfc\u5165\u65b9\u5728\u7b2c\u4e00\u6b21 map \u65f6\u5c31\u628a buffer pin \u6b7b\u5728 VRAM，\u5bfc\u51fa\u65b9\u7684 TTM \u6839\u672c\u65e0\u6cd5\u6267\u884c\u4e0a\u56fe\u4e2d\u95f4\u90a3\u6b21\u642c\u79fb\u3002\u52a8\u6001\u673a\u5236\u901a\u8fc7\u4e00\u6b21 move_notify \u56de\u8c03，\u628a\u300c\u5148\u901a\u77e5\u3001\u540e\u642c\u79fb\u3001\u518d\u91cd\u6620\u5c04\u300d\u4e09\u62cd\u62c6\u5f00，\u65e2\u8ba9\u5171\u4eab\u5f97\u4ee5\u7ee7\u7eed，\u53c8\u628a\u8fc1\u79fb\u7684\u81ea\u7531\u8fd8\u7ed9\u4e86\u5bfc\u51fa\u65b9\u3002<\/p>\n

        6. \u5c0f\u7ed3\u4e0e\u5ef6\u4f38<\/h3>\n

        \u52a8\u6001 dma-buf \u7684\u5168\u90e8\u8981\u4e49\u53ef\u4ee5\u6536\u675f\u4e3a\u4e09\u53e5\u8bdd：<\/p>\n

      • move_notify \u662f\u6838\u5fc3：\u5bfc\u51fa\u65b9\u642c\u79fb\u524d\u904d\u5386 attachments \u9010\u4e2a\u901a\u77e5\u52a8\u6001\u5bfc\u5165\u65b9\u4f5c\u5e9f\u65e7\u6620\u5c04；\u5b83\u628a\u300c\u5171\u4eab\u300d\u4e0e\u300c\u53ef\u8fc1\u79fb\u300d\u8fd9\u5bf9\u77db\u76fe\u62c6\u89e3\u4e3a\u300c\u5148\u9884\u8b66\u3001\u518d\u642c\u79fb\u3001\u540e\u91cd\u5efa\u300d\u7684\u65f6\u5e8f\u534f\u4f5c\u3002<\/li>\n
      • pin\/unpin \u662f\u4e34\u65f6\u4f8b\u5916：\u4ec5\u52a8\u6001\u5bfc\u5165\u65b9\u53ef\u8c03\u7528，\u7528\u4e8e scanout \u7b49\u786e\u9700\u7a33\u5b9a\u5730\u5740\u7684\u77ed\u6682\u573a\u666f，\u7528\u5b8c\u5373 unpin \u8ba9 buffer \u56de\u5f52\u53ef\u8fc1\u79fb\u5e38\u6001\u2014\u2014\u7edd\u4e0d\u53ef\u9000\u5316\u4e3a\u53d8\u76f8\u7684\u6c38\u4e45\u9489\u6b7b\u3002<\/li>\n
      • \u9759\u6001\u4e0e\u52a8\u6001\u7684\u5206\u6c34\u5cad\u5728 attach：\u662f\u5426\u4f20 importer_ops（\u542b move_notify）\u4e00\u6b21\u51b3\u5b9a\u4eba\u683c；\u9759\u6001\u4ee5 pin \u6362\u7b80\u5355，\u52a8\u6001\u4ee5\u91cd\u6620\u5c04\u6362\u7075\u6d3b\u3002<\/li>\n

        \u81f3\u6b64，5.2 \u8282\u4ece anon_inode\u3001dma-buf \u673a\u5236\u3001dma-buf exporter \u5b9e\u73b0\u3001attach\/map\/sg_table\u7684importer \u5b9e\u73b0 \u5230\u672c\u8282\u7684\u52a8\u6001\u673a\u5236，\u5df2\u7ecf\u628a\u300c\u5185\u6838\u5185\u90e8\u4e24\u4e2a\u9a71\u52a8\u5982\u4f55\u5171\u4eab\u4e00\u5757 buffer\u300d\u8bb2\u6e05\u695a\u4e86\u3002\u4f46\u53c8\u81ea\u7136\u800c\u7136\u5f15\u51fa\u53e6\u4e00\u4e2a\u65b9\u5411：\u7528\u6237\u6001\u80fd\u4e0d\u80fd\u76f4\u63a5\u5206\u914d\u4e00\u5757\u53ef\u5171\u4eab\u3001\u96f6\u62f7\u8d1d\u7684 dma-buf，\u800c\u4e0d\u5fc5\u7ecf\u8fc7\u67d0\u4e2a\u5177\u4f53 GPU \u9a71\u52a8？ \u8fd9\u4e2a\u95ee\u9898\u53ef\u4ee5\u4e0a\u5347\u5230\u4e00\u4e2a\u66f4\u5927\u7684\u4e3b\u9898：\u5982\u4f55\u628a\u5185\u6838\u6001\u4e00\u4e9b\u673a\u5236\u8ba9\u7528\u6237\u6001\u4e5f\u53ef\u7528，\u8fd9\u4e2a\u4e3b\u9898\u540c\u6837\u4ee4\u4eba\u5174\u594b\u3002\u90a3\u5c31\u8ba9\u6211\u4eec\u7ee7\u7eed\u5174\u594b\u5730\u524d\u884c\u5427，\u8fd9\u6b63\u662f 5.2.6 dma-buf heaps \u4e0e udmabuf \u8981\u56de\u7b54\u7684\u2014\u2014\u5b83\u628a dma-buf \u7684\u5206\u914d\u6743\u4ece\u5185\u6838\u9a71\u52a8\u4e0b\u653e\u5230\u7528\u6237\u6001\u3002<\/p>\n

        \n

        \u6211\u4eec\u8fd9\u91cc\u7684\u5206\u6790\u53ea\u662f\u5171\u4eab\u4e0b\u7684\u8fc1\u79fb\u6d89\u53ca\u7684\u51b0\u5c71\u4e00\u89d2，\u80cc\u540e\u6d89\u53ca\u7684\u903b\u8f91\u5f88\u591a，\u4e0b\u9762\u662f\u76f8\u5173\u7684\u4e3b\u9898：<\/p>\n

        \u76f8\u5173\u9605\u8bfb：<\/p>\n

          \n
        • move_notify \u91cc\u5bf9 GPU \u9875\u8868\u7684\u66f4\u65b0（amdgpu_vm_handle_moved）\u5c5e\u4e8e\u7b2c\u4e5d\u7ae0 GPUVM \u7684\u8303\u7574；<\/li>\n
        • dma_resv \u9501\u4e0e fence \u7684\u914d\u5408\u8be6\u89c1 6.3 \u9690\u5f0f\u540c\u6b65 dma_resv\u3002<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

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