opencl: route large q6_K lm_head to the flat GEMV (#26427)

* add a direct size condition for `large` weights; the original
  dimension condition is insufficient -- q6_K lm_head for gemma-4 E2B
  has [1536, 262144], which is big enough to slowdown gemv_noshuffle but
  does not satisfy the dimension condition (ne0 >= 2048)

diff --git a/ggml/src/ggml-opencl/ggml-opencl.cpp b/ggml/src/ggml-opencl/ggml-opencl.cpp
index 915c8e7b903f9e68605ff1cb8c2d4c0c90fe2eff..fc0fce0d780ac1c333d28a96434a4b21e91c9669 100644 (file)
--- a/ggml/src/ggml-opencl/ggml-opencl.cpp
+++ b/ggml/src/ggml-opencl/ggml-opencl.cpp
@@ -7065,7 +7065,7 @@ static inline bool use_flat_gemv_for_large_m_q4_K(const ggml_tensor *tensor) {
     return tensor->ne[1] >= 32768 && tensor->ne[2] == 1 && tensor->ne[3] == 1;
 }
 
-static inline bool use_flat_gemv_for_large_m_q6_K(const ggml_tensor *tensor) {
+static inline bool use_flat_gemv_for_large_m_q6_K(const ggml_backend_opencl_context *backend_ctx, const ggml_tensor *tensor) {
     // gemv_noshuffle variant perf drops for large M, use flat variant for large M.
     // threshold is well above typical hidden/FFN dims, but below typical vocab sizes.
     // q6_K flat gemv is worse for smaller K; 2048 seems to be a reasonable threshold.
@@ -7083,7 +7083,15 @@ static inline bool use_flat_gemv_for_large_m_q6_K(const ggml_tensor *tensor) {
     if ((tensor->ne[1] % 128 != 0) && tensor->ne[2] == 1 && tensor->ne[3] == 1) {
         return true;
     }
-    return tensor->ne[1] >= 32768 && tensor->ne[0] >= 2048 && tensor->ne[2] == 1 && tensor->ne[3] == 1;
+
+    // The gemv_noshuffle slowdown tracks TOTAL weight size, not ne0 alone; ne0 >= 2048 is a
+    // proxy for "large weight" that misses a narrow-hidden vocab-scale lm_head.
+    // Add a direct size escape so such weights also take the flat path, without changing
+    // which weights ne0 >= 2048 already routes there.
+    // The size escape is not taken on the A7X since its compiler miscompiles the flat K-quant GEMV
+    return tensor->ne[1] >= 32768
+        && (tensor->ne[0] >= 2048 || (backend_ctx->adreno_gen != ADRENO_GPU_GEN::A7X && ggml_nbytes(tensor) >= (256ull << 20)))
+        && tensor->ne[2] == 1 && tensor->ne[3] == 1;
 }
 
 static bool ggml_opencl_supports_op(ggml_backend_dev_t dev, const struct ggml_tensor * op) {
@@ -9403,7 +9411,7 @@ static void ggml_backend_opencl_buffer_set_tensor(ggml_backend_buffer_t buffer,
         cl_kernel kernel;
 #ifdef GGML_OPENCL_USE_ADRENO_KERNELS
         kernel = backend_ctx->kernel_convert_block_q6_K;
-        if (use_adreno_kernels(backend_ctx, tensor) && !use_flat_gemv_for_large_m_q6_K(tensor)) {
+        if (use_adreno_kernels(backend_ctx, tensor) && !use_flat_gemv_for_large_m_q6_K(backend_ctx, tensor)) {
             kernel = backend_ctx->kernel_convert_block_q6_K_noshuffle;
         }
 #else
@@ -9436,7 +9444,7 @@ static void ggml_backend_opencl_buffer_set_tensor(ggml_backend_buffer_t buffer,
         tensor->extra  = extra;
 
 #ifdef GGML_OPENCL_USE_ADRENO_KERNELS
-        if (use_adreno_kernels(backend_ctx, tensor) && !use_flat_gemv_for_large_m_q6_K(tensor)) {
+        if (use_adreno_kernels(backend_ctx, tensor) && !use_flat_gemv_for_large_m_q6_K(backend_ctx, tensor)) {
             cl_int M = tensor->ne[1];   // ne01
             cl_int K = tensor->ne[0];   // ne00
 
@@ -10473,7 +10481,7 @@ static void ggml_backend_opencl_buffer_get_tensor(ggml_backend_buffer_t buffer,
             CL_CHECK(clReleaseMemObject(data_device));
             return;
         }
-        if (use_adreno_kernels(backend_ctx, tensor) && !use_flat_gemv_for_large_m_q6_K(tensor)) {
+        if (use_adreno_kernels(backend_ctx, tensor) && !use_flat_gemv_for_large_m_q6_K(backend_ctx, tensor)) {
             static ggml_cl_buffer buf_trans_ql;
             static ggml_cl_buffer buf_trans_qh;
             static ggml_cl_buffer buf_trans_s;
@@ -18895,7 +18903,7 @@ static void ggml_cl_mul_mat(ggml_backend_t backend, const ggml_tensor * src0, co
         }
 
         // q6_K x fp32
-        if (src0t == GGML_TYPE_Q6_K && src1t == GGML_TYPE_F32 && !use_flat_gemv_for_large_m_q6_K(src0)) {
+        if (src0t == GGML_TYPE_Q6_K && src1t == GGML_TYPE_F32 && !use_flat_gemv_for_large_m_q6_K(backend_ctx, src0)) {
             ggml_cl_mul_mat_q6_K_f32_adreno(backend, src0, src1, dst);
             return;
         }