From: Reese Levine <redacted>
Date: Wed, 18 Feb 2026 23:06:29 +0000 (-0700)
Subject: ggml webgpu: Fix bug in dispatching large matrix-vector multiplication (llama/19535)
X-Git-Tag: v0.9.8~121
X-Git-Url: https://git.djapps.eu/?a=commitdiff_plain;h=e10bfc0db2caae8bbf396b33a90b86668d5dbe1d;p=pkg%2Fggml%2Fsources%2Fggml

ggml webgpu: Fix bug in dispatching large matrix-vector multiplication (llama/19535)

* Fix bug in dispatching large matrix-vector multiplication
---

diff --git a/src/ggml-webgpu/ggml-webgpu.cpp b/src/ggml-webgpu/ggml-webgpu.cpp
index 17bb2f47..b5fee480 100644
--- a/src/ggml-webgpu/ggml-webgpu.cpp
+++ b/src/ggml-webgpu/ggml-webgpu.cpp
@@ -1121,7 +1121,8 @@ static webgpu_command ggml_webgpu_mul_mat(webgpu_context & ctx,
         uint32_t batches       = dst->ne[2] * dst->ne[3];
         uint32_t output_groups = CEIL_DIV(dst->ne[0], decisions->outputs_per_wg);
         uint32_t total_wg      = output_groups * batches;
-        wg_x                   = total_wg % ctx->global_ctx->capabilities.limits.maxComputeWorkgroupsPerDimension;
+        // TODO: split large sizes into multiple batches to avoid way over-provisioning workgroups
+        wg_x = std::min(total_wg, ctx->global_ctx->capabilities.limits.maxComputeWorkgroupsPerDimension);
         wg_y = CEIL_DIV(total_wg, ctx->global_ctx->capabilities.limits.maxComputeWorkgroupsPerDimension);
     } else if (use_fast) {
         auto decisions = static_cast<ggml_webgpu_mul_mat_shader_decisions *>(pipeline.context.get());