From 4f3a2a4b79e32efae8d291cae9322689454be368 Mon Sep 17 00:00:00 2001
From: Neo Zhang <zhang.jianyu@outlook.com>
Date: Tue, 1 Sep 2026 18:35:47 +0800
Subject: [PATCH] sycl : support limit max alloc memory within 2GB for
 host-pinned memory (llama/27559)

---
 ggml/src/ggml-sycl/ggml-sycl.cpp | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/ggml/src/ggml-sycl/ggml-sycl.cpp b/ggml/src/ggml-sycl/ggml-sycl.cpp
index 290fb4676..626f0f3bf 100644
--- a/ggml/src/ggml-sycl/ggml-sycl.cpp
+++ b/ggml/src/ggml-sycl/ggml-sycl.cpp
@@ -107,6 +107,7 @@ int g_ggml_sycl_enable_flash_attention = 1;
 int g_ggml_sycl_dev2dev_memcpy = DEV2DEV_MEMCPY_SYCL;
 int g_ggml_sycl_usm_system = 0;
 int g_ggml_sycl_enable_host_pinned_mem = 1;
+int g_ggml_sycl_host_pinned_mem_2g = 0;
 int g_ggml_sycl_get_mem_api = MEMORY_API_TYPE_LEVEL_ZERO;
 
 
@@ -355,6 +356,8 @@ static void ggml_check_sycl() try {
         g_ggml_sycl_enable_host_pinned_mem =
             ggml_sycl_get_env("GGML_SYCL_ENABLE_HOST_PINNED_MEM", 1);
 
+        g_ggml_sycl_host_pinned_mem_2g =
+            ggml_sycl_get_env("GGML_SYCL_HOST_PINNED_MEM_2G", 0) & g_ggml_sycl_enable_host_pinned_mem;
 
         GGML_SYCL_DEBUG("[SYCL] call ggml_check_sycl\n");
 
@@ -457,6 +460,7 @@ static void ggml_check_sycl() try {
 
         GGML_LOG_INFO("  GGML_SYCL_USM_SYSTEM: %d\n", g_ggml_sycl_usm_system);
         GGML_LOG_INFO("  GGML_SYCL_ENABLE_HOST_PINNED_MEM: %d\n", g_ggml_sycl_enable_host_pinned_mem);
+        GGML_LOG_INFO("  GGML_SYCL_HOST_PINNED_MEM_2G: %d\n", g_ggml_sycl_host_pinned_mem_2g);
 
 /* NOT REMOVE, keep it for next optimize for XMX.
 #if defined(SYCL_USE_XMX)
@@ -977,8 +981,12 @@ static size_t ggml_backend_sycl_buffer_type_get_alignment(ggml_backend_buffer_ty
 }
 
 static size_t ggml_backend_sycl_buffer_type_get_max_size(ggml_backend_buffer_type_t buft) {
-    return dpct::get_current_device().get_max_mem_alloc_size();
-
+    size_t max_alloc_size = dpct::get_current_device().get_max_mem_alloc_size();
+    if (g_ggml_sycl_host_pinned_mem_2g) {
+        return std::min(max_alloc_size, (size_t) 2LL*1024*1024*1024);
+    } else {
+        return max_alloc_size;
+    }
     GGML_UNUSED(buft);
 }
 
@@ -1551,7 +1559,12 @@ static size_t ggml_backend_sycl_host_buffer_type_get_max_size(ggml_backend_buffe
 
     if (g_ggml_sycl_enable_host_pinned_mem) {
         ggml_backend_sycl_device_context * dev_ctx = (ggml_backend_sycl_device_context *) buft->device->context;
-        return dpct::dev_mgr::instance().get_device(dev_ctx->device).get_max_mem_alloc_size();
+        size_t max_alloc_size = dpct::dev_mgr::instance().get_device(dev_ctx->device).get_max_mem_alloc_size();
+        if (g_ggml_sycl_host_pinned_mem_2g) {
+            return std::min(max_alloc_size, (size_t) 2LL*1024*1024*1024);
+        } else {
+            return max_alloc_size;
+        }
     } else {
         return SIZE_MAX;
     }