Merge pull request #209 from ROCm/andriy/merge_from_public

Update develop branch from public repository

python/ck4inductor/universal_gemm/gen_instances.py

+# SPDX-License-Identifier: MIT
+# Copyright (c) 2018-2024, Advanced Micro Devices, Inc. All rights reserved.
+
 import logging
 import os
 import subprocess
-from dataclasses import fields, replace
+from dataclasses import replace
 from functools import lru_cache, partial
 from typing import List
 

python/ck4inductor/universal_gemm/op.py

+# SPDX-License-Identifier: MIT
+# Copyright (c) 2018-2024, Advanced Micro Devices, Inc. All rights reserved.
+
 from dataclasses import asdict, dataclass
 from typing import Optional, Tuple
 

python/ck4inductor/util.py

+# SPDX-License-Identifier: MIT
+# Copyright (c) 2018-2024, Advanced Micro Devices, Inc. All rights reserved.
+
 import functools
 import os
 
 
 @functools.lru_cache(None)
 def library_path():
-    return os.path.join(os.path.dirname(__file__), 'library')
+    return os.path.join(os.path.dirname(__file__), "library")

test/CMakeLists.txt

@@ -210,3 +210,4 @@ if(SUPPORTED_GPU_TARGETS MATCHES "gfx942" AND CK_HIP_VERSION_MAJOR GREATER_EQUAL
     add_subdirectory(smfmac_op)
 endif()
 add_subdirectory(position_embedding)
+add_subdirectory(scatter_gather)

test/ck_tile/CMakeLists.txt

 add_subdirectory(image_to_column)
+add_subdirectory(gemm)

test/ck_tile/gemm/CMakeLists.txt

+# Currently ck_tile is only built on gfx9
+if(GPU_TARGETS MATCHES "gfx9")
+    add_gtest_executable(test_ck_tile_gemm_mem_pipeline test_gemm_mem_pipeline.cpp)
+endif()

test/ck_tile/gemm/test_gemm_mem_pipeline.cpp

+// SPDX-License-Identifier: MIT
+// Copyright (c) 2024, Advanced Micro Devices, Inc. All rights reserved.
+
+#include <tuple>
+
+#include "gtest/gtest.h"
+
+#include "ck_tile/host.hpp"
+#include "test_gemm_mem_pipeline_util.hpp"
+
+using F16 = ck_tile::half_t;
+using F32 = float;
+
+using Row = ck_tile::tensor_layout::gemm::RowMajor;
+using Col = ck_tile::tensor_layout::gemm::ColumnMajor;
+
+// clang-format off
+using KernelTypes = ::testing::Types<
+    //         ALayout, BLayout, CLayout, ADataType, BDataType, AccDataType, CDataType
+    std::tuple<    Row,     Col,     Row,       F16,       F16,         F32,      F16>,
+    std::tuple<    Col,     Row,     Row,       F16,       F16,         F32,      F16>,
+    std::tuple<    Row,     Row,     Row,       F16,       F16,         F32,      F16>,
+    std::tuple<    Col,     Col,     Row,       F16,       F16,         F32,      F16>
+    >;
+// clang-format on
+
+TYPED_TEST_SUITE(TestCkTileGemmMemPipeline, KernelTypes);
+
+#include "test_gemm_mem_pipeline_ut_cases.inc"

test/ck_tile/gemm/test_gemm_mem_pipeline_ut_cases.inc

+#pragma once
+
+TYPED_TEST(TestCkTileGemmMemPipeline, SmallM)
+{
+    std::vector<int> Ms{1, 2, 3, 4, 5, 6};
+    constexpr int N = 1024;
+    constexpr int K = 320;
+
+    for(int M : Ms)
+        this->Run(M, N, K);
+}
+
+TYPED_TEST(TestCkTileGemmMemPipeline, MidLargeM)
+{
+    std::vector<int> Ms{127, 255, 312, 799, 1573};
+    constexpr int N = 1024;
+    constexpr int K = 320;
+
+    for(int M : Ms)
+        this->Run(M, N, K);
+}
+
+TYPED_TEST(TestCkTileGemmMemPipeline, PaddK)
+{
+    std::vector<int> Ms{127};
+    constexpr int N = 1024;
+    constexpr int K = 432;
+
+    for(int M : Ms)
+        this->Run(M, N, K);
+}
+
+TYPED_TEST(TestCkTileGemmMemPipeline, Regular)
+{
+    std::vector<int> Ms{512};
+    constexpr int N = 1024;
+    constexpr int K = 512;
+
+    for(int M : Ms)
+        this->Run(M, N, K);
+}

test/ck_tile/gemm/test_gemm_mem_pipeline_util.hpp

+// SPDX-License-Identifier: MIT
+// Copyright (c) 2024, Advanced Micro Devices, Inc. All rights reserved.
+#pragma once
+
+#include <sstream>
+#include <gtest/gtest.h>
+
+#include "ck_tile/core.hpp"
+#include "ck_tile/host.hpp"
+#include "ck_tile/host/kernel_launch.hpp"
+#include "ck_tile/ops/epilogue.hpp"
+#include "ck_tile/ops/gemm.hpp"
+
+template <typename Tuple>
+class TestCkTileGemmMemPipeline : public ::testing::Test
+{
+    protected:
+    using ALayout     = std::tuple_element_t<0, Tuple>;
+    using BLayout     = std::tuple_element_t<1, Tuple>;
+    using CLayout     = std::tuple_element_t<2, Tuple>;
+    using ADataType   = std::tuple_element_t<3, Tuple>;
+    using BDataType   = std::tuple_element_t<4, Tuple>;
+    using AccDataType = std::tuple_element_t<5, Tuple>;
+    using CDataType   = std::tuple_element_t<6, Tuple>;
+    // TODO: expose tile size through test t-param ?
+
+    struct gemm_basic_args
+    {
+        const void* p_a;
+        const void* p_b;
+        void* p_c;
+        ck_tile::index_t kbatch;
+        ck_tile::index_t M;
+        ck_tile::index_t N;
+        ck_tile::index_t K;
+        ck_tile::index_t stride_A;
+        ck_tile::index_t stride_B;
+        ck_tile::index_t stride_C;
+    };
+
+    void invoke_gemm(const gemm_basic_args& args, const ck_tile::stream_config& s)
+    {
+        // TODO: This should be parameterized in tests
+        constexpr ck_tile::index_t M_Tile = 128;
+        constexpr ck_tile::index_t N_Tile = 128;
+        constexpr ck_tile::index_t K_Tile = 32;
+
+        constexpr ck_tile::index_t M_Warp = 2;
+        constexpr ck_tile::index_t N_Warp = 2;
+        constexpr ck_tile::index_t K_Warp = 1;
+
+        constexpr ck_tile::index_t M_Warp_Tile = 32;
+        constexpr ck_tile::index_t N_Warp_Tile = 32;
+        constexpr ck_tile::index_t K_Warp_Tile = 8;
+
+        constexpr bool kPadA = true;
+        constexpr bool kPadB = true;
+        constexpr bool kPadC = true;
+
+        constexpr int kBlockPerCu = 1;
+
+        // ===============================================
+
+        using GemmShape =
+            ck_tile::TileGemmShape<ck_tile::sequence<M_Tile, N_Tile, K_Tile>,
+                                   ck_tile::sequence<M_Warp, N_Warp, K_Warp>,
+                                   ck_tile::sequence<M_Warp_Tile, N_Warp_Tile, K_Warp_Tile>>;
+        using TilePartitioner = ck_tile::GemmTilePartitioner<GemmShape>;
+
+        using GemmEpilogue = ck_tile::Default2DEpilogue<
+            ck_tile::Default2DEpilogueProblem<AccDataType, CDataType, false, kPadC>>;
+
+        using Traits = ck_tile::TileGemmTraits<kPadA, kPadB, kPadC, ALayout, BLayout, CLayout>;
+
+        using BaseGemmPipeline = ck_tile::BaseGemmPipelineAgBgCrMem<
+            ck_tile::GemmPipelineProblem<ADataType, BDataType, AccDataType, GemmShape, Traits>>;
+
+        const ck_tile::index_t num_loop    = TilePartitioner::GetLoopNum(args.K);
+        const bool has_hot_loop            = BaseGemmPipeline::BlockHasHotloop(num_loop);
+        const ck_tile::TailNumber tail_num = BaseGemmPipeline::GetBlockLoopTailNum(num_loop);
+
+        const auto Run = [&](const auto has_hot_loop_, const auto tail_number_) {
+            constexpr bool has_hot_loop_v = has_hot_loop_.value;
+            constexpr auto tail_number_v  = tail_number_.value;
+
+            using GemmPipeline = ck_tile::GemmPipelineAgBgCrMem<
+                ck_tile::UniversalGemmPipelineProblem<ADataType,
+                                                      BDataType,
+                                                      AccDataType,
+                                                      GemmShape,
+                                                      Traits,
+                                                      ck_tile::GemmPipelineScheduler::Intrawave,
+                                                      has_hot_loop_v,
+                                                      tail_number_v>>;
+            using Kernel = ck_tile::GemmKernel<TilePartitioner, GemmPipeline, GemmEpilogue>;
+            auto kargs   = Kernel::MakeKargs(args.p_a,
+                                           args.p_b,
+                                           args.p_c,
+                                           args.M,
+                                           args.N,
+                                           args.K,
+                                           args.stride_A,
+                                           args.stride_B,
+                                           args.stride_C);
+
+            const dim3 grids      = Kernel::GridSize(args.M, args.N, args.kbatch);
+            constexpr dim3 blocks = Kernel::BlockSize();
+
+            if(s.log_level_ > 0)
+            {
+                std::cout << "Lunching kernel with args:"
+                          << " grid: {" << grids.x << ", " << grids.y << ", " << grids.z << "}"
+                          << ", blocks: {" << blocks.x << ", " << blocks.y << ", " << blocks.z
+                          << "}" << std::endl;
+            }
+
+            ck_tile::launch_kernel(
+                s, ck_tile::make_kernel<blocks.x, kBlockPerCu>(Kernel{}, grids, blocks, 0, kargs));
+        };
+
+        if(has_hot_loop)
+        {
+            // Tail pipeline One to Seven
+            if(tail_num == ck_tile::TailNumber::One)
+            {
+                Run(ck_tile::bool_constant<true>{},
+                    ck_tile::integral_constant<ck_tile::TailNumber, ck_tile::TailNumber::One>{});
+            }
+            else if(tail_num == ck_tile::TailNumber::Full)
+            {
+                Run(ck_tile::bool_constant<true>{},
+                    ck_tile::integral_constant<ck_tile::TailNumber, ck_tile::TailNumber::Full>{});
+            }
+
+            if constexpr(BaseGemmPipeline::PrefetchStages > 2)
+            {
+                if(tail_num == ck_tile::TailNumber::Two)
+                {
+                    Run(ck_tile::bool_constant<true>{},
+                        ck_tile::integral_constant<ck_tile::TailNumber,
+                                                   ck_tile::TailNumber::Two>{});
+                }
+            }
+            if constexpr(BaseGemmPipeline::PrefetchStages > 3)
+            {
+                if(tail_num == ck_tile::TailNumber::Three)
+                {
+                    Run(ck_tile::bool_constant<true>{},
+                        ck_tile::integral_constant<ck_tile::TailNumber,
+                                                   ck_tile::TailNumber::Three>{});
+                }
+            }
+            if constexpr(BaseGemmPipeline::PrefetchStages > 4)
+            {
+                if(tail_num == ck_tile::TailNumber::Four)
+                {
+                    Run(ck_tile::bool_constant<true>{},
+                        ck_tile::integral_constant<ck_tile::TailNumber,
+                                                   ck_tile::TailNumber::Four>{});
+                }
+            }
+            if constexpr(BaseGemmPipeline::PrefetchStages > 5)
+            {
+                if(tail_num == ck_tile::TailNumber::Five)
+                {
+                    Run(ck_tile::bool_constant<true>{},
+                        ck_tile::integral_constant<ck_tile::TailNumber,
+                                                   ck_tile::TailNumber::Five>{});
+                }
+            }
+            if constexpr(BaseGemmPipeline::PrefetchStages > 6)
+            {
+                if(tail_num == ck_tile::TailNumber::Six)
+                {
+                    Run(ck_tile::bool_constant<true>{},
+                        ck_tile::integral_constant<ck_tile::TailNumber,
+                                                   ck_tile::TailNumber::Six>{});
+                }
+            }
+            if constexpr(BaseGemmPipeline::PrefetchStages > 7)
+            {
+                if(tail_num == ck_tile::TailNumber::Seven)
+                {
+                    Run(ck_tile::bool_constant<true>{},
+                        ck_tile::integral_constant<ck_tile::TailNumber,
+                                                   ck_tile::TailNumber::Seven>{});
+                }
+            }
+        }
+        else
+        {
+            // Tail number always Full - #PrefetchStages
+            if(tail_num == ck_tile::TailNumber::Full)
+            {
+                Run(ck_tile::bool_constant<false>{},
+                    ck_tile::integral_constant<ck_tile::TailNumber, ck_tile::TailNumber::Full>{});
+            }
+            else
+            {
+                std::ostringstream err;
+                err << "When there's no hot loop, this tail number \"" << tail_num
+                    << "\" is not supported! " << __FILE__ << ":" << __LINE__
+                    << ", in function: " << __func__;
+                throw std::runtime_error(err.str());
+            }
+        }
+    }
+
+    public:
+    std::vector<int> k_batches_;
+
+    void SetUp() override { k_batches_ = {1}; }
+
+    void Run(const int M,
+             const int N,
+             const int K,
+             const int StrideA = 0,
+             const int StrideB = 0,
+             const int StrideC = 0)
+    {
+        for(auto kb : k_batches_)
+        {
+            RunSingle(M, N, K, StrideA, StrideB, StrideC, kb);
+        }
+    }
+
+    void RunSingle(const int M,
+                   const int N,
+                   const int K,
+                   const int StrideA,
+                   const int StrideB,
+                   const int StrideC,
+                   int kbatch = 1)
+    {
+        using namespace ck_tile::literals;
+
+        auto f_host_tensor_descriptor = [](std::size_t row,
+                                           std::size_t col,
+                                           std::size_t stride,
+                                           auto layout) {
+            if constexpr(std::is_same_v<decltype(layout), ck_tile::tensor_layout::gemm::RowMajor>)
+            {
+                return ck_tile::HostTensorDescriptor({row, col}, {stride, 1_uz});
+            }
+            else
+            {
+                return ck_tile::HostTensorDescriptor({row, col}, {1_uz, stride});
+            }
+        };
+
+        auto f_get_default_stride =
+            [](std::size_t row, std::size_t col, std::size_t stride, auto layout) {
+                if(stride == 0)
+                {
+                    // give a chance if stride is zero, return a default packed stride
+                    if constexpr(std::is_same_v<decltype(layout),
+                                                ck_tile::tensor_layout::gemm::RowMajor>)
+                    {
+                        return col;
+                    }
+                    else
+                    {
+                        return row;
+                    }
+                }
+                else
+                    return stride;
+            };
+
+        std::size_t stride_A = f_get_default_stride(M, K, StrideA, ALayout{});
+        std::size_t stride_B = f_get_default_stride(K, N, StrideB, BLayout{});
+        std::size_t stride_C = f_get_default_stride(M, N, StrideC, CLayout{});
+
+        ck_tile::HostTensor<ADataType> a_m_k(f_host_tensor_descriptor(M, K, stride_A, ALayout{}));
+        ck_tile::HostTensor<BDataType> b_k_n(f_host_tensor_descriptor(K, N, stride_B, BLayout{}));
+        ck_tile::HostTensor<CDataType> c_m_n_dev_result(
+            f_host_tensor_descriptor(M, N, stride_C, CLayout{}));
+
+        ck_tile::FillUniformDistributionIntegerValue<ADataType>{-5, 5}(a_m_k);
+        ck_tile::FillUniformDistributionIntegerValue<BDataType>{-5, 5}(b_k_n);
+
+        ck_tile::DeviceMem a_m_k_dev_buf(a_m_k.get_element_space_size_in_bytes());
+        ck_tile::DeviceMem b_k_n_dev_buf(b_k_n.get_element_space_size_in_bytes());
+        ck_tile::DeviceMem c_m_n_dev_buf(c_m_n_dev_result.get_element_space_size_in_bytes());
+
+        a_m_k_dev_buf.ToDevice(a_m_k.data());
+        b_k_n_dev_buf.ToDevice(b_k_n.data());
+        c_m_n_dev_buf.SetZero();
+        c_m_n_dev_result.SetZero();
+
+        gemm_basic_args args;
+        args.p_a      = a_m_k_dev_buf.GetDeviceBuffer();
+        args.p_b      = b_k_n_dev_buf.GetDeviceBuffer();
+        args.p_c      = c_m_n_dev_buf.GetDeviceBuffer();
+        args.kbatch   = kbatch;
+        args.M        = M;
+        args.N        = N;
+        args.K        = K;
+        args.stride_A = stride_A;
+        args.stride_B = stride_B;
+        args.stride_C = stride_C;
+
+        invoke_gemm(args, ck_tile::stream_config{nullptr, false});
+
+        c_m_n_dev_buf.FromDevice(c_m_n_dev_result.data());
+        bool pass = true;
+
+        ck_tile::HostTensor<CDataType> c_m_n_host_ref(
+            f_host_tensor_descriptor(M, N, stride_C, CLayout{}));
+        c_m_n_host_ref.SetZero();
+
+        ck_tile::reference_gemm<ADataType, BDataType, AccDataType, CDataType>(
+            a_m_k, b_k_n, c_m_n_host_ref);
+
+        pass = ck_tile::check_err(c_m_n_dev_result, c_m_n_host_ref);
+        EXPECT_TRUE(pass);
+    }
+};

test/scatter_gather/CMakeLists.txt

+add_test_executable(test_scatter_gather scatter_gather.cpp)
+# target_compile_options(test_scatter_gather PRIVATE -v --save-temps -Wno-gnu-line-marker)

test/scatter_gather/scatter_gather.cpp

+// SPDX-License-Identifier: MIT
+// Copyright (c) 2018-2024, Advanced Micro Devices, Inc. All rights reserved.
+
+#include <vector>
+#include <iostream>
+#include <numeric>
+#include <cassert>
+#include <cstdlib>
+#include <iostream>
+#include <time.h>
+#include <unordered_set>
+
+#include "ck_tile/core.hpp"
+
+#ifndef TEST_SCATTER_GATHER_VERBOSE
+#define TEST_SCATTER_GATHER_VERBOSE 1
+#endif
+
+#define HIP_CALL(call)                                                              \
+    do                                                                              \
+    {                                                                               \
+        hipError_t err = call;                                                      \
+        if(err != hipSuccess)                                                       \
+        {                                                                           \
+            printf("[hiperror](%d) fail to call %s", static_cast<int>(err), #call); \
+            exit(0);                                                                \
+        }                                                                           \
+    } while(0)
+
+/*
+TODO:
+This is a simple design of scatter/gather through indexing transform, with limitations
+We may design a scatter/gather adaptor layer directly inside tile window
+*/
+template <ck_tile::index_t ROW_TILE_SIZE = 8,
+          ck_tile::index_t COL_TILE_SIZE = 32 * 8,
+          ck_tile::index_t BLOCK_SIZE    = 256,
+          ck_tile::index_t ALIGNMENT     = 8,
+          typename INDEX_BUF_TYPE        = ck_tile::index_t,
+          typename DATA_TYPE             = ck_tile::fp16_t>
+__global__ void row_scatter_gather(const INDEX_BUF_TYPE* src_row_idx_ptr,
+                                   const INDEX_BUF_TYPE* dst_row_idx_ptr,
+                                   const DATA_TYPE* src_ptr,
+                                   DATA_TYPE* dst_ptr,
+                                   ck_tile::index_t n_row_total,
+                                   ck_tile::index_t /*n_row_select*/,
+                                   ck_tile::index_t n_cols)
+{
+    using namespace ck_tile;
+
+    // some constexpr vars
+    constexpr index_t vec = ALIGNMENT;
+    static_assert(COL_TILE_SIZE % vec == 0);
+    constexpr index_t col_lanes = COL_TILE_SIZE / vec;
+    constexpr index_t warp_size = ck_tile::get_warp_size();
+    static_assert(warp_size % col_lanes == 0);
+    constexpr index_t row_lanes = warp_size / col_lanes;
+    constexpr index_t num_warps = BLOCK_SIZE / warp_size;
+    static_assert(ROW_TILE_SIZE % (num_warps * row_lanes) == 0);
+    constexpr index_t row_repeat = ROW_TILE_SIZE / (num_warps * row_lanes);
+    static_assert(
+        row_repeat == 1,
+        "currently indexing not support(and would be not performant) if row_repeat has more");
+
+    // tile partitioner
+    index_t tile_col_idx = 0;
+    index_t tile_row_idx = blockIdx.x * ROW_TILE_SIZE;
+
+    // create our tild distribution, which tell us the location of different threads
+    constexpr auto src_dist = make_static_tile_distribution(
+        tile_distribution_encoding<
+            sequence<1>,
+            tuple<sequence<row_repeat, num_warps, row_lanes>, sequence<col_lanes, vec>>,
+            tuple<sequence<1>, sequence<1, 2>>,
+            tuple<sequence<1>, sequence<2, 0>>,
+            sequence<1, 2>,
+            sequence<0, 1>>{});
+    const auto coord     = src_dist.calculate_index();
+    const auto row_coord = coord[number<0>{}] + tile_row_idx;
+
+    // load the current row index from the indexing buffer. we do not use ck_tile utility here
+    INDEX_BUF_TYPE src_row_id = src_row_idx_ptr[row_coord];
+    INDEX_BUF_TYPE dst_row_id = dst_row_idx_ptr[row_coord];
+
+    // printf("-- tid:%d, src_row_id:%d, dst_row_id:%d\n", static_cast<int>(threadIdx.x),
+    // static_cast<int>(src_row_id), static_cast<int>(dst_row_id));
+
+    const auto src_view =
+        make_naive_tensor_view<address_space_enum::global>(src_ptr,
+                                                           make_tuple(n_row_total, n_cols),
+                                                           make_tuple(n_cols, 1),
+                                                           number<vec>{}, // alignement
+                                                           number<1>{});
+
+    const auto src_gather_view = transform_tensor_view(
+        src_view,
+        make_tuple(make_indexing_transform(
+                       n_row_total,
+                       src_row_id), // here we replace row_idx  which is loaded from another buffer
+                   make_pass_through_transform(n_cols)),
+        make_tuple(sequence<0>{}, sequence<1>{}),
+        make_tuple(sequence<0>{}, sequence<1>{}));
+
+    auto src_tile = make_tile_window(src_gather_view,
+                                     make_tuple(number<ROW_TILE_SIZE>{}, number<COL_TILE_SIZE>{}),
+                                     {tile_row_idx, tile_col_idx},
+                                     src_dist);
+
+    const auto dst_view =
+        make_naive_tensor_view<address_space_enum::global>(dst_ptr,
+                                                           make_tuple(n_row_total, n_cols),
+                                                           make_tuple(n_cols, 1),
+                                                           number<vec>{},
+                                                           number<1>{});
+
+    const auto dst_scatter_view = transform_tensor_view(
+        dst_view,
+        make_tuple(make_indexing_transform(
+                       n_row_total,
+                       dst_row_id), // here we replace row_idx  which is loaded from another buffer
+                   make_pass_through_transform(n_cols)),
+        make_tuple(sequence<0>{}, sequence<1>{}),
+        make_tuple(sequence<0>{}, sequence<1>{}));
+
+    auto dst_tile = make_tile_window(dst_scatter_view,
+                                     make_tuple(number<ROW_TILE_SIZE>{}, number<COL_TILE_SIZE>{}),
+                                     {tile_row_idx, tile_col_idx},
+                                     src_dist /*reuse distribution*/);
+
+    // we finished descriptor construction and index calculation, now start load/store
+    for(auto i = 0; i < n_cols; i += COL_TILE_SIZE)
+    {
+        // note that scatter/gather are just the same API when doing load store as normal memory
+        // operation
+        auto data = load_tile(src_tile);
+        store_tile(dst_tile, data);
+
+        move_tile_window(src_tile, {number<0>{}, number<COL_TILE_SIZE>{}});
+        move_tile_window(dst_tile, {number<0>{}, number<COL_TILE_SIZE>{}});
+    }
+}
+
+union pixel
+{
+    struct __attribute__((packed))
+    {
+        unsigned int r : 6;
+        unsigned int c : 10;
+    };
+    ushort data;
+};
+
+struct unique_linear_rand
+{
+    unique_linear_rand(int capacity_) : capacity(capacity_) {}
+    std::unordered_set<int> set;
+    int gen()
+    {
+        if(static_cast<int>(set.size()) >= capacity)
+        {
+            printf("overflow, but will give you an number as well\n");
+            return std::rand() % capacity;
+        }
+        while(1)
+        {
+            int r = std::rand() % capacity;
+            if(set.count(r) == 1)
+            {
+                continue;
+            }
+            set.insert(r);
+            return r;
+        }
+    }
+
+    int capacity;
+};
+
+int main()
+{
+    int row_total  = 64;
+    int row_select = 8 * 2;
+    int col        = 256 * 2;
+    using fp16_t   = ck_tile::fp16_t;
+
+    constexpr int row_tile = 8;
+    constexpr int col_tile = 256;
+
+    fp16_t* src = reinterpret_cast<fp16_t*>(malloc(row_total * col * sizeof(fp16_t)));
+    for(int i_r = 0; i_r < row_total; i_r++)
+    {
+        for(int i_c = 0; i_c < col; i_c++)
+        {
+            int i = i_r * col + i_c;
+            pixel p;
+            p.r      = i_r;
+            p.c      = i_c;
+            ushort d = p.data;
+            src[i]   = ck_tile::bit_cast<fp16_t>(d); // for simplicity, just cast
+        }
+    }
+
+    fp16_t* dst  = reinterpret_cast<fp16_t*>(malloc(row_total * col * sizeof(fp16_t)));
+    int* src_idx = reinterpret_cast<int*>(malloc(row_select * sizeof(int)));
+    int* dst_idx = reinterpret_cast<int*>(malloc(row_select * sizeof(int)));
+    // std::srand(std::time(std::nullptr));
+    // std::srand(11935);
+    std::srand(std::time(nullptr));
+    auto src_gen = unique_linear_rand(row_total);
+    auto dst_gen = unique_linear_rand(row_total); // dst index must be unique. src is fine
+    for(int i_r = 0; i_r < row_select; i_r++)
+    {
+        src_idx[i_r] = src_gen.gen();
+        dst_idx[i_r] = dst_gen.gen();
+    }
+
+    void* dev_src;
+    void* dev_dst;
+    void* dev_src_idx;
+    void* dev_dst_idx;
+    HIP_CALL(hipMalloc(&dev_src, row_total * col * sizeof(fp16_t)));
+    HIP_CALL(hipMalloc(&dev_dst, row_total * col * sizeof(fp16_t)));
+    HIP_CALL(hipMalloc(&dev_src_idx, row_select * sizeof(int)));
+    HIP_CALL(hipMalloc(&dev_dst_idx, row_select * sizeof(int)));
+
+    HIP_CALL(hipMemcpy(dev_src, src, row_total * col * sizeof(fp16_t), hipMemcpyHostToDevice));
+    HIP_CALL(hipMemcpy(dev_src_idx, src_idx, row_select * sizeof(int), hipMemcpyHostToDevice));
+    HIP_CALL(hipMemcpy(dev_dst_idx, dst_idx, row_select * sizeof(int), hipMemcpyHostToDevice));
+
+    constexpr int bdim = 256;
+    int gdim           = (row_select + row_tile - 1) / row_tile;
+    row_scatter_gather<row_tile, col_tile><<<gdim, bdim>>>(reinterpret_cast<int*>(dev_src_idx),
+                                                           reinterpret_cast<int*>(dev_dst_idx),
+                                                           reinterpret_cast<fp16_t*>(dev_src),
+                                                           reinterpret_cast<fp16_t*>(dev_dst),
+                                                           row_total,
+                                                           row_select,
+                                                           col);
+
+    HIP_CALL(hipMemcpy(dst, dev_dst, row_total * col * sizeof(fp16_t), hipMemcpyDeviceToHost));
+
+#if TEST_SCATTER_GATHER_VERBOSE
+    printf("select row:");
+    for(int i_r = 0; i_r < row_select; i_r++)
+    {
+        printf("%d->%d->%d ", i_r, src_idx[i_r], dst_idx[i_r]);
+    }
+    printf("\n");
+#endif
+
+    int err_cnt = 0;
+    for(int i_r = 0; i_r < row_select; i_r++)
+    {
+        for(int i_c = 0; i_c < col; i_c++)
+        {
+            int i      = dst_idx[i_r] * col + i_c;
+            pixel p    = ck_tile::bit_cast<pixel>(dst[i]);
+            bool is_ok = p.r == src_idx[i_r] && p.c == i_c;
+            if(!is_ok)
+            {
+                if(i_c == 0)
+                    printf("(%d)pixel: %dx%d -> %d\n", i_r, p.r, p.c, dst_idx[i_r]);
+                err_cnt++;
+            }
+        }
+    }
+#if TEST_SCATTER_GATHER_VERBOSE
+    printf("err:%d\n", err_cnt);
+#endif
+
+    free(src);
+    free(dst);
+    free(src_idx);
+    free(dst_idx);
+    return err_cnt == 0 ? 0 : -1;
+}