From ebb0e9d0ed7eccd5b320d56d60ef50cf3c87b105 Mon Sep 17 00:00:00 2001
From: Akarshan Biswas <akarshan@menlo.ai>
Date: Mon, 14 Jul 2025 15:07:55 +0530
Subject: [PATCH] SYCL: use 1D kernel for set_rows (llama/14618)

* SYCL: Use 1D kernel for set_rows

* Remove dangling comment

* Refactor and use ceil_div
---
 ggml/src/ggml-sycl/set_rows.cpp | 82 ++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 41 deletions(-)

diff --git a/ggml/src/ggml-sycl/set_rows.cpp b/ggml/src/ggml-sycl/set_rows.cpp
index 4a76a63d..3091fab3 100644
--- a/ggml/src/ggml-sycl/set_rows.cpp
+++ b/ggml/src/ggml-sycl/set_rows.cpp
@@ -6,46 +6,49 @@ static constexpr bool is_arithmetic_v() {
     return std::is_arithmetic_v<T> || std::is_same_v<T, sycl::half> || std::is_same_v<T, sycl::ext::oneapi::bfloat16>;
 }
 }
+
 template<typename TIn, typename TOut>
 static inline std::enable_if_t<utils::is_arithmetic_v<TIn>() && utils::is_arithmetic_v<TOut>(), void>
 convert (const char* src, char* dst) {
     auto src_val = *reinterpret_cast<const TIn*>(src);
     auto dst_val = sycl::vec<TIn, 1>(src_val).template convert<TOut, sycl::rounding_mode::automatic>()[0];
-   *reinterpret_cast<TOut*>(dst) = dst_val;;
+   *reinterpret_cast<TOut*>(dst) = dst_val;
 }
 
 template<typename TIn, typename TOut>
 static void k_set_rows(
         const char * __restrict__ src0, const int64_t * __restrict__ src1, char * __restrict__ dst,
-        const int64_t ne00, const int64_t ne01, const int64_t ne11, const int64_t ne12,
+        const int64_t ne00, const int64_t ne01, const int64_t ne02,
+        const int64_t ne11, const int64_t ne12,
         const size_t nb01, const size_t nb02, const size_t nb03,
         const size_t nb10, const size_t nb11, const size_t nb12,
         const size_t nb1, const size_t nb2, const size_t nb3,
         const size_t src_type_size, const size_t dst_type_size,
-        const sycl::nd_item<3> & item_ct1) {
+        const int64_t total_elements,
+        const sycl::nd_item<1> & item_ct1) {
 
-    const int i03 = item_ct1.get_group(0);
-    const int i02 = item_ct1.get_group(1);
-    const int i01 = item_ct1.get_group(2) * item_ct1.get_local_range(1) + item_ct1.get_local_id(1);  // Row index
-
-    if (i01 >= ne01) {
+    const int64_t i = item_ct1.get_global_linear_id();
+    if (i >= total_elements) {
         return;
     }
 
-    const int i12 = i03 % ne12;
-    const int i11 = i02 % ne11;
-    const int i10 = i01;
+    const int64_t i03 = i / (ne00 * ne01 * ne02);
+    const int64_t i02 = (i - i03 * ne00 * ne01 * ne02) / (ne00 * ne01);
+    const int64_t i01 = (i - i03 * ne00 * ne01 * ne02 - i02 * ne00 * ne01) / ne00;
+    const int64_t i00 = i - i03 * ne00 * ne01 * ne02 - i02 * ne00 * ne01 - i01 * ne00;
+
+    const int64_t i12 = i03 % ne12;
+    const int64_t i11 = i02 % ne11;
+    const int64_t i10 = i01;
 
     const int64_t dst_row = *(const int64_t *)((const char *)src1 + calculate_offset<3>({nb10, nb11, nb12}, {i10, i11, i12}));
 
     const char * src0_row = src0 + calculate_offset<3>({nb01, nb02, nb03}, {i01, i02, i03});
-    char * dst_row_ptr    = dst + dst_row*nb1 + i02*nb2 + i03*nb3;
+    const char * src_elem = src0_row + i00 * src_type_size;
+    char * dst_row_ptr = dst + dst_row*nb1 + i02*nb2 + i03*nb3;
+    char * dst_elem = dst_row_ptr + i00 * dst_type_size;
 
-    for (int col = item_ct1.get_local_id(0); col < ne00; col += item_ct1.get_local_range(0)) {
-        const char * src_elem = src0_row + col * src_type_size;
-        char * dst_elem       = dst_row_ptr + col * dst_type_size;
-        convert<TIn, TOut>(src_elem, dst_elem);
-    }
+    convert<TIn, TOut>(src_elem, dst_elem);
 }
 
 template<typename TIn, typename TOut>
@@ -58,33 +61,30 @@ static void set_rows_sycl(
         const size_t src_type_size, const size_t dst_type_size,
         queue_ptr stream) {
 
-    constexpr int max_threads_per_row = 64; // KEEPING 64 for now
-    const int threads_per_row     = std::min((int)ne00, max_threads_per_row);
+    const int64_t total_elements = ne00 * ne01 * ne02 * ne03;
 
-    constexpr int max_threads_per_block = 64;
-    const int rows_per_block        = std::max(1, max_threads_per_block / threads_per_row);
+    constexpr int block_size = 64;
+    const int64_t grid_size = ceil_div(total_elements, block_size);
 
-    const sycl::range<3> block_size(1, rows_per_block, threads_per_row);
-    const sycl::range<3> grid_size(ne03, ne02, (ne01 + rows_per_block - 1) / rows_per_block);
-
-        sycl_parallel_for(
-            stream,
-            sycl::nd_range<3>(grid_size * block_size, block_size),
-            [=](sycl::nd_item<3> item_ct1) {
-                k_set_rows<TIn, TOut>(
-                    src0_d, src1_d, dst_d,
-                    ne00, ne01, ne11, ne12,
-                    nb01, nb02, nb03,
-                    nb10, nb11, nb12,
-                    nb1, nb2, nb3,
-                    src_type_size, dst_type_size,
-                    item_ct1
-                );
-            }
-        );
+    sycl_parallel_for(
+        stream,
+        sycl::nd_range<1>(grid_size * block_size, block_size),
+        [=](sycl::nd_item<1> item_ct1) {
+            k_set_rows<TIn, TOut>(
+                src0_d, src1_d, dst_d,
+                ne00, ne01, ne02,
+                ne11, ne12,
+                nb01, nb02, nb03,
+                nb10, nb11, nb12,
+                nb1, nb2, nb3,
+                src_type_size, dst_type_size,
+                total_elements,
+                item_ct1
+            );
+        }
+    );
 }
 
-
 void ggml_sycl_op_set_rows(ggml_backend_sycl_context & ctx, ggml_tensor * dst) {
     scope_op_debug_print scope_dbg_print(__func__, dst, /*num_src=*/2);
     const ggml_tensor * src0 = dst->src[0];
@@ -122,7 +122,7 @@ void ggml_sycl_op_set_rows(ggml_backend_sycl_context & ctx, ggml_tensor * dst) {
                 nb1, nb2, nb3,
                 sizeof(float), sizeof(sycl::half),
                 stream
-        );
+            );
             break;
         default:
             GGML_ABORT("Unsupported tensor type!");