TopK Tiling

功能说明

用于获取Topk Tiling参数。

Ascend C提供Topk Tiling API，方便用户获取Topk kernel计算时所需的Tiling参数。阅读本节之前，请先参考Tiling实现了解Tiling实现基本流程。

获取Tiling参数主要分为如下两步：

1. 获取Topk接口计算所需最小和最大临时空间大小，注意该步骤不是必须的，只是作为一个参考，供合理分配计算空间。
2. 获取Topk kernel侧接口所需tiling参数。
   Topk Tiling结构体的定义如下，开发者无需关注该tiling结构的具体信息，只需要传递到kernel侧，传入Topk高阶API接口，直接进行使用即可。

   struct TopkTiling {
       int32_t tmpLocalSize = 0;
       int32_t allDataSize = 0;
       int32_t innerDataSize = 0;
       uint32_t sortRepeat = 0;
       int32_t mrgSortRepeat = 0;
       int32_t kAlignFourBytes = 0;
       int32_t kAlignTwoBytes = 0;
       int32_t maskOffset = 0;
       int32_t maskVreducev2FourBytes = 0;
       int32_t maskVreducev2TwoBytes = 0;
       int32_t mrgSortSrc1offset = 0;
       int32_t mrgSortSrc2offset = 0;
       int32_t mrgSortSrc3offset = 0;
       int32_t mrgSortTwoQueueSrc1Offset = 0;
       int32_t mrgFourQueueTailPara1 = 0;
       int32_t mrgFourQueueTailPara2 = 0;
       int32_t srcIndexOffset = 0;
       int32_t topkNSmallTmpLocalSize = 0;
       int32_t topkMrgSrc1MaskSizeOffset = 0;
       int32_t topkNSmallSrcIndexOffset = 0;
       uint32_t vreduceValMask0 = 0;
       uint32_t vreduceValMask1 = 0;
       uint32_t vreduceIdxMask0 = 0;
       uint32_t vreduceIdxMask1 = 0;
       uint16_t vreducehalfValMask0 = 0;
       uint16_t vreducehalfValMask1 = 0;
       uint16_t vreducehalfValMask2 = 0;
       uint16_t vreducehalfValMask3 = 0;
       uint16_t vreducehalfValMask4 = 0;
       uint16_t vreducehalfValMask5 = 0;
       uint16_t vreducehalfValMask6 = 0;
       uint16_t vreducehalfValMask7 = 0;
       uint16_t copyUbToUbBlockCount = 0;
   };

函数原型

1

bool GetTopKMaxMinTmpSize(const platform_ascendc::PlatformAscendC &ascendcPlatform, const int32_t inner, const int32_t outter, const bool isReuseSource, const bool isInitIndex, enum TopKMode mode, const bool isLargest, const uint32_t dataTypeSize, uint32_t &maxValue, uint32_t &minValue)

1

bool TopKTilingFunc(const platform_ascendc::PlatformAscendC &ascendcPlatform, const int32_t inner, const int32_t outter, const int32_t k, const uint32_t dataTypeSize, const bool isInitIndex, enum TopKMode mode, const bool isLargest, optiling::TopkTiling &topKTiling)

参数说明

返回值

GetTopKMaxMinTmpSize返回值为true/false，true表示成功拿到Topk接口内部计算需要的最大和最小临时空间大小；false表示获取失败。

TopKTilingFunc返回值为true/false，true表示成功拿到Topk的Tiling各项参数值；false表示获取失败。

调用示例

如下样例介绍了使用Topk高阶API时host侧获取Tiling参数的流程以及该参数如何在kernel侧使用。

1. 将Topk Tiling结构体参数增加至TilingData结构体，作为TilingData结构体的一个字段。

   namespace optiling {
   BEGIN_TILING_DATA_DEF(TilingData)
       TILING_DATA_FIELD_DEF(uint32_t, totalLength);
       TILING_DATA_FIELD_DEF(uint32_t, tilenum);
       //添加其他tiling字段
       ...                                
       TILING_DATA_FIELD_DEF(int32_t, k);
       TILING_DATA_FIELD_DEF(bool, islargest);
       TILING_DATA_FIELD_DEF(bool, isinitindex);
       TILING_DATA_FIELD_DEF(bool, ishasfinish);
       TILING_DATA_FIELD_DEF(uint32_t, tmpsize);
       TILING_DATA_FIELD_DEF(int32_t, outter);
       TILING_DATA_FIELD_DEF(int32_t, inner);
       TILING_DATA_FIELD_DEF(int32_t, n);
       TILING_DATA_FIELD_DEF_STRUCT(TopkTiling, topkTilingData);
   END_TILING_DATA_DEF;
   REGISTER_TILING_DATA_CLASS(TopkCustom, TilingData)
   }

2. Tiling实现函数中，首先调用GetTopKMaxMinTmpSize接口获取Topk接口能完成计算所需最大/最小临时空间大小，根据该范围结合实际的内存使用情况设置合适的空间大小；然后根据输入shape等信息获取Topk kernel侧接口所需tiling参数。

   namespace optiling {
   const uint32_t BLOCK_DIM = 8;
   const uint32_t TILE_NUM = 8;
   const int32_t OUTTER = 2;
   const int32_t INNER = 32;
   const int32_t N = 32;
   const int32_t K = 8;
   const bool IS_LARGEST = true;
   const bool IS_INITINDEX = true;
   const bool IS_REUSESOURCE = false;
   static ge::graphStatus TilingFunc(gert::TilingContext* context)
   {
       TilingData tiling;
       uint32_t totalLength = context->GetInputTensor(0)->GetShapeSize();
       context->SetBlockDim(BLOCK_DIM);
       tiling.set_totalLength(totalLength);
       tiling.set_tileNum(TILE_NUM);
       tiling.set_k(K);
       tiling.set_outter(OUTTER);
       tiling.set_inner(INNER);
       tiling.set_n(N);
       tiling.set_islargest(IS_LARGEST);
       tiling.set_isinitindex(IS_INITINDEX);
       // 设置其他Tiling参数
       ... 
       // 本样例中仅做为样例说明，通过GetTopKMaxMinTmpSize获取最小值并传入，来保证功能正确，开发者可以根据需要传入合适的空间大小。
       uint32_t maxsize = 0;
       uint32_t minsize = 0;
       uint32_t dtypesize = 4;  // float类型
       auto ascendcPlatform = platform_ascendc::PlatformAscendC(context->GetPlatformInfo());
       AscendC::TopKTilingFunc(ascendcPlatform, tiling.inner, tiling.outter, tiling.k, dtypesize, tiling.isinitindex, AscendC::TopKMode::TOPK_NSMALL, tiling.islargest, tiling.topkTilingData);
       AscendC::GetTopKMaxMinTmpSize(ascendcPlatform, tiling.inner, tiling.outter, IS_REUSESOURCE, tiling.isinitindex, AscendC::TopKMode::TOPK_NSMALL, tiling.islargest, dtypesize, maxsize, minsize);
       tiling.set_tmpsize(minsize);
        ... // 其他逻辑
       tiling.SaveToBuffer(context->GetRawTilingData()->GetData(), context->GetRawTilingData()->GetCapacity());
       context->GetRawTilingData()->SetDataSize(tiling.GetDataSize());
       size_t *currentWorkspace = context->GetWorkspaceSizes(1);
       currentWorkspace[0] = 0;
       return ge::GRAPH_SUCCESS;
   }
   } // namespace optiling

3. 对应的kernel侧通过在核函数中调用GET_TILING_DATA获取TilingData，继而将TilingData中的Topk Tiling信息传入Topk接口参与计算。完整的kernel侧样例请参考调用示例。

   extern "C" __global__ __aicore__ void topk_custom(GM_ADDR srcVal, GM_ADDR srcIdx, GM_ADDR finishLocal, GM_ADDR dstVal, GM_ADDR dstIdx, GM_ADDR tiling) {
   {
       GET_TILING_DATA(tilingData, tiling);
       KernelTopK<float, true, true, false, false, AscendC::TopKMode::TOPK_NSMALL> op;
       op.Init(srcVal, srcIdx, finishLocal, dstVal, dstIdx, tilingData.k, tilingData.islargest, tilingData.tmpsize, tilingData.outter, tilingData.inner, tilingData.n,tilingData.topkTilingData);
       op.Process();
   }