SYCL: fix multi-GPU system RAM exhaustion by using Level Zero allocations

.devops/intel.Dockerfile

@@ -5,8 +5,15 @@ ARG ONEAPI_VERSION=2025.3.3-0-devel-ubuntu24.04
 FROM intel/deep-learning-essentials:$ONEAPI_VERSION AS build
 
 ARG GGML_SYCL_F16=OFF
+ARG LEVEL_ZERO_VERSION=1.28.2
+ARG LEVEL_ZERO_UBUNTU_VERSION=u24.04
 RUN apt-get update && \
-    apt-get install -y git libssl-dev
+    apt-get install -y git libssl-dev wget ca-certificates && \
+    cd /tmp && \
+    wget -q "https://github.com/oneapi-src/level-zero/releases/download/v${LEVEL_ZERO_VERSION}/level-zero_${LEVEL_ZERO_VERSION}%2B${LEVEL_ZERO_UBUNTU_VERSION}_amd64.deb" -O level-zero.deb && \
+    wget -q "https://github.com/oneapi-src/level-zero/releases/download/v${LEVEL_ZERO_VERSION}/level-zero-devel_${LEVEL_ZERO_VERSION}%2B${LEVEL_ZERO_UBUNTU_VERSION}_amd64.deb" -O level-zero-devel.deb && \
+    apt-get -o Dpkg::Options::="--force-overwrite" install -y ./level-zero.deb ./level-zero-devel.deb && \
+    rm -f /tmp/level-zero.deb /tmp/level-zero-devel.deb
 
 WORKDIR /app
 
@@ -109,4 +116,3 @@ WORKDIR /app
 HEALTHCHECK CMD [ "curl", "-f", "http://localhost:8080/health" ]
 
 ENTRYPOINT [ "/app/llama-server" ]
-

.github/workflows/build-sycl.yml

@@ -50,6 +50,8 @@ jobs:
     env:
       ONEAPI_ROOT: /opt/intel/oneapi/
       ONEAPI_INSTALLER_VERSION: "2025.3.3"
+      LEVEL_ZERO_VERSION: "1.28.2"
+      LEVEL_ZERO_UBUNTU_VERSION: "u24.04"
 
     continue-on-error: true
 
@@ -71,6 +73,14 @@ jobs:
           wget https://registrationcenter-download.intel.com/akdlm/IRC_NAS/56f7923a-adb8-43f3-8b02-2b60fcac8cab/intel-deep-learning-essentials-2025.3.3.16_offline.sh -O intel-deep-learning-essentials_offline.sh
           sudo bash intel-deep-learning-essentials_offline.sh -s -a --silent --eula accept
 
+      - name: Install Level Zero SDK
+        shell: bash
+        run: |
+          cd /tmp
+          wget -q "https://github.com/oneapi-src/level-zero/releases/download/v${LEVEL_ZERO_VERSION}/level-zero_${LEVEL_ZERO_VERSION}%2B${LEVEL_ZERO_UBUNTU_VERSION}_amd64.deb" -O level-zero.deb
+          wget -q "https://github.com/oneapi-src/level-zero/releases/download/v${LEVEL_ZERO_VERSION}/level-zero-devel_${LEVEL_ZERO_VERSION}%2B${LEVEL_ZERO_UBUNTU_VERSION}_amd64.deb" -O level-zero-devel.deb
+          sudo apt-get install -y ./level-zero.deb ./level-zero-devel.deb
+
       - name: Clone
         id: checkout
         uses: actions/checkout@v6
@@ -107,6 +117,7 @@ jobs:
     env:
       WINDOWS_BASEKIT_URL: https://registrationcenter-download.intel.com/akdlm/IRC_NAS/b60765d1-2b85-4e85-86b6-cb0e9563a699/intel-deep-learning-essentials-2025.3.3.18_offline.exe
       WINDOWS_DPCPP_MKL: intel.oneapi.win.cpp-dpcpp-common:intel.oneapi.win.mkl.devel:intel.oneapi.win.dnnl:intel.oneapi.win.tbb.devel
+      LEVEL_ZERO_SDK_URL: https://github.com/oneapi-src/level-zero/releases/download/v1.28.2/level-zero-win-sdk-1.28.2.zip
       ONEAPI_ROOT: "C:/Program Files (x86)/Intel/oneAPI"
       ONEAPI_INSTALLER_VERSION: "2025.3.3"
     steps:
@@ -127,6 +138,13 @@ jobs:
         run: |
           scripts/install-oneapi.bat $WINDOWS_BASEKIT_URL $WINDOWS_DPCPP_MKL
 
+      - name: Install Level Zero SDK
+        shell: pwsh
+        run: |
+          Invoke-WebRequest -Uri "${{ env.LEVEL_ZERO_SDK_URL }}" -OutFile "level-zero-win-sdk.zip"
+          Expand-Archive -Path "level-zero-win-sdk.zip" -DestinationPath "C:/level-zero-sdk" -Force
+          "LEVEL_ZERO_V1_SDK_PATH=C:/level-zero-sdk" | Out-File -FilePath $env:GITHUB_ENV -Append
+
       - name: ccache
         uses: ggml-org/ccache-action@v1.2.21
         with:

.github/workflows/release.yml

@@ -600,6 +600,7 @@ jobs:
     env:
       WINDOWS_BASEKIT_URL: https://registrationcenter-download.intel.com/akdlm/IRC_NAS/b60765d1-2b85-4e85-86b6-cb0e9563a699/intel-deep-learning-essentials-2025.3.3.18_offline.exe
       WINDOWS_DPCPP_MKL: intel.oneapi.win.cpp-dpcpp-common:intel.oneapi.win.mkl.devel:intel.oneapi.win.dnnl:intel.oneapi.win.tbb.devel
+      LEVEL_ZERO_SDK_URL: https://github.com/oneapi-src/level-zero/releases/download/v1.28.2/level-zero-win-sdk-1.28.2.zip
       ONEAPI_ROOT: "C:/Program Files (x86)/Intel/oneAPI"
       ONEAPI_INSTALLER_VERSION: "2025.3.3"
 
@@ -621,6 +622,13 @@ jobs:
         run: |
           scripts/install-oneapi.bat $WINDOWS_BASEKIT_URL $WINDOWS_DPCPP_MKL
 
+      - name: Install Level Zero SDK
+        shell: pwsh
+        run: |
+          Invoke-WebRequest -Uri "${{ env.LEVEL_ZERO_SDK_URL }}" -OutFile "level-zero-win-sdk.zip"
+          Expand-Archive -Path "level-zero-win-sdk.zip" -DestinationPath "C:/level-zero-sdk" -Force
+          "LEVEL_ZERO_V1_SDK_PATH=C:/level-zero-sdk" | Out-File -FilePath $env:GITHUB_ENV -Append
+
       - name: ccache
         uses: ggml-org/ccache-action@v1.2.21
         with:
@@ -655,6 +663,13 @@ jobs:
           cp "${{ env.ONEAPI_ROOT }}/compiler/latest/bin/ur_adapter_opencl.dll" ./build/bin
           cp "${{ env.ONEAPI_ROOT }}/compiler/latest/bin/ur_loader.dll" ./build/bin
           cp "${{ env.ONEAPI_ROOT }}/compiler/latest/bin/ur_win_proxy_loader.dll" ./build/bin
+          ZE_LOADER_DLL=$(find "${{ env.ONEAPI_ROOT }}" "$LEVEL_ZERO_V1_SDK_PATH" -iname ze_loader.dll -print -quit 2>/dev/null || true)
+          if [ -n "$ZE_LOADER_DLL" ]; then
+            echo "Using Level Zero loader: $ZE_LOADER_DLL"
+            cp "$ZE_LOADER_DLL" ./build/bin
+          else
+            echo "Level Zero loader DLL not found in oneAPI or SDK; relying on system driver/runtime"
+          fi
 
           cp "${{ env.ONEAPI_ROOT }}/compiler/latest/bin/sycl8.dll" ./build/bin
           cp "${{ env.ONEAPI_ROOT }}/compiler/latest/bin/svml_dispmd.dll" ./build/bin
@@ -695,6 +710,8 @@ jobs:
     env:
       ONEAPI_ROOT: /opt/intel/oneapi/
       ONEAPI_INSTALLER_VERSION: "2025.3.3"
+      LEVEL_ZERO_VERSION: "1.28.2"
+      LEVEL_ZERO_UBUNTU_VERSION: "u24.04"
 
     steps:
       - name: Clone
@@ -718,6 +735,14 @@ jobs:
           wget https://registrationcenter-download.intel.com/akdlm/IRC_NAS/56f7923a-adb8-43f3-8b02-2b60fcac8cab/intel-deep-learning-essentials-2025.3.3.16_offline.sh -O intel-deep-learning-essentials_offline.sh
           sudo bash intel-deep-learning-essentials_offline.sh -s -a --silent --eula accept
 
+      - name: Install Level Zero SDK
+        shell: bash
+        run: |
+          cd /tmp
+          wget -q "https://github.com/oneapi-src/level-zero/releases/download/v${LEVEL_ZERO_VERSION}/level-zero_${LEVEL_ZERO_VERSION}%2B${LEVEL_ZERO_UBUNTU_VERSION}_amd64.deb" -O level-zero.deb
+          wget -q "https://github.com/oneapi-src/level-zero/releases/download/v${LEVEL_ZERO_VERSION}/level-zero-devel_${LEVEL_ZERO_VERSION}%2B${LEVEL_ZERO_UBUNTU_VERSION}_amd64.deb" -O level-zero-devel.deb
+          sudo apt-get install -y ./level-zero.deb ./level-zero-devel.deb
+
       - name: ccache
         uses: ggml-org/ccache-action@v1.2.21
         with:

docs/backend/SYCL.md

@@ -720,6 +720,7 @@ use 1 SYCL GPUs: [0] with Max compute units:512
 | GGML_SYCL_GRAPH    | OFF *(default)* \|ON *(Optional)*     | Enable build with [SYCL Graph extension](https://github.com/intel/llvm/blob/sycl/sycl/doc/extensions/experimental/sycl_ext_oneapi_graph.asciidoc). |
 | GGML_SYCL_DNN      | ON *(default)* \|OFF *(Optional)*     | Enable build with oneDNN.                   |
 | GGML_SYCL_HOST_MEM_FALLBACK | ON *(default)* \|OFF *(Optional)* | Allow host memory fallback when device memory is full during quantized weight reorder. Enables inference to continue at reduced speed (reading over PCIe) instead of failing. Requires Linux kernel 6.8+. |
+| GGML_SYCL_SUPPORT_LEVEL_ZERO | ON *(default)* \|OFF *(Optional)* | Enable Level Zero API for device memory allocation. Requires Level Zero headers/library at build time and Intel GPU driver (Level Zero runtime) at run time. Reduces system RAM usage during multi-GPU inference. |
 | CMAKE_C_COMPILER   | `icx` *(Linux)*, `icx/cl` *(Windows)* | Set `icx` compiler for SYCL code path.      |
 | CMAKE_CXX_COMPILER | `icpx` *(Linux)*, `icx` *(Windows)*   | Set `icpx/icx` compiler for SYCL code path. |
 
@@ -733,9 +734,10 @@ use 1 SYCL GPUs: [0] with Max compute units:512
 | GGML_SYCL_ENABLE_FLASH_ATTN | 1 (default) or 0| Enable Flash-Attention. It can reduce memory usage. The performance impact depends on the LLM.|
 | GGML_SYCL_DISABLE_OPT | 0 (default) or 1 | Disable optimize features for Intel GPUs. (Recommended to 1 for intel devices older than Gen 10) |
 | GGML_SYCL_DISABLE_GRAPH | 0 or 1 (default) | Disable running computations through SYCL Graphs feature. Disabled by default because SYCL Graph is still on development, no better performance. |
+| GGML_SYCL_ENABLE_LEVEL_ZERO | 1 (default) or 0 | Use Level Zero API for device memory allocation instead of SYCL. Reduces system RAM usage on Intel dGPUs by avoiding DMA-buf/TTM host memory staging. Requires GGML_SYCL_SUPPORT_LEVEL_ZERO=ON at build time. |
 | GGML_SYCL_DISABLE_DNN | 0 (default) or 1 | Disable running computations through oneDNN and always use oneMKL. |
 | ZES_ENABLE_SYSMAN | 0 (default) or 1 | Support to get free memory of GPU by sycl::aspect::ext_intel_free_memory.<br>Recommended to use when --split-mode = layer |
-| UR_L0_ENABLE_RELAXED_ALLOCATION_LIMITS | 0 (default) or 1 | Support malloc device memory more than 4GB.|
+| UR_L0_ENABLE_RELAXED_ALLOCATION_LIMITS | 0 (default) or 1 | Allow SYCL/Unified Runtime Level Zero device allocations larger than 4 GiB. llama.cpp's direct Level Zero allocation path requests the relaxed maximum-size limit itself when GGML_SYCL_ENABLE_LEVEL_ZERO=1. |
 
 ## Design Rule
 
@@ -811,7 +813,7 @@ use 1 SYCL GPUs: [0] with Max compute units:512
 
 - `ggml_backend_sycl_buffer_type_alloc_buffer: can't allocate 5000000000 Bytes of memory on device`
 
-  You need to enable to support 4GB memory malloc by:
+  With the default `GGML_SYCL_ENABLE_LEVEL_ZERO=1`, llama.cpp requests Level Zero's relaxed maximum-size allocation limit directly. If Level Zero support is disabled at build time or runtime and the allocation goes through SYCL/Unified Runtime instead, enable support for allocations larger than 4 GiB by:
   ```
     export UR_L0_ENABLE_RELAXED_ALLOCATION_LIMITS=1
     set UR_L0_ENABLE_RELAXED_ALLOCATION_LIMITS=1

ggml/CMakeLists.txt

@@ -249,6 +249,7 @@ option(GGML_SYCL                            "ggml: use SYCL"
 option(GGML_SYCL_F16                        "ggml: use 16 bit floats for sycl calculations"   OFF)
 option(GGML_SYCL_GRAPH                      "ggml: enable graphs in the SYCL backend"         ON)
 option(GGML_SYCL_HOST_MEM_FALLBACK          "ggml: allow host memory fallback in SYCL reorder (requires kernel 6.8+)" ON)
+option(GGML_SYCL_SUPPORT_LEVEL_ZERO         "ggml: use Level Zero API in SYCL backend"  ON)
 option(GGML_SYCL_DNN                        "ggml: enable oneDNN in the SYCL backend"         ON)
 set   (GGML_SYCL_TARGET "INTEL" CACHE STRING
                                             "ggml: sycl target device")

ggml/src/ggml-sycl/CMakeLists.txt

@@ -39,6 +39,18 @@ if (WIN32)
         set(CMAKE_CXX_COMPILER "icx")
         set(CMAKE_CXX_COMPILER_ID "IntelLLVM")
     endif()
+    # Level Zero SDK path for Windows (only when GGML_SYCL_SUPPORT_LEVEL_ZERO is enabled)
+    if(GGML_SYCL_SUPPORT_LEVEL_ZERO)
+        if(DEFINED ENV{LEVEL_ZERO_V1_SDK_PATH})
+            set(LEVEL_ZERO_V1_SDK_PATH $ENV{LEVEL_ZERO_V1_SDK_PATH})
+            if(EXISTS "${LEVEL_ZERO_V1_SDK_PATH}")
+                target_include_directories(ggml-sycl PRIVATE "${LEVEL_ZERO_V1_SDK_PATH}/include")
+                set(LEVEL_ZERO_V1_SDK_LIB_PATH "${LEVEL_ZERO_V1_SDK_PATH}/lib")
+            else()
+                message(WARNING "LEVEL_ZERO_V1_SDK_PATH set but folder not found: ${LEVEL_ZERO_V1_SDK_PATH}")
+            endif()
+        endif()
+    endif()
 endif()
 
 macro(detect_and_find_package package_name)
@@ -93,6 +105,23 @@ endif()
 
 target_compile_options(ggml-sycl PRIVATE "-Wno-narrowing")
 
+message(STATUS "GGML_SYCL_SUPPORT_LEVEL_ZERO ${GGML_SYCL_SUPPORT_LEVEL_ZERO}")
+if (GGML_SYCL_SUPPORT_LEVEL_ZERO)
+    # Link against Level Zero loader for direct device memory allocation.
+    # Avoids sycl::malloc_device triggering DMA-buf/TTM system RAM staging
+    # in the xe kernel driver during multi-GPU inference.
+    find_path(LEVEL_ZERO_INCLUDE_DIR level_zero/ze_api.h HINTS ${ONEAPI_ROOT}/include ${LEVEL_ZERO_V1_SDK_PATH}/include)
+    find_library(ZE_LOADER_LIB ze_loader HINTS ${ONEAPI_ROOT}/lib ${LEVEL_ZERO_V1_SDK_LIB_PATH} ENV LD_LIBRARY_PATH)
+    if(ZE_LOADER_LIB AND LEVEL_ZERO_INCLUDE_DIR)
+        target_link_libraries(ggml-sycl PRIVATE ${ZE_LOADER_LIB})
+        target_compile_definitions(ggml-sycl PRIVATE GGML_SYCL_SUPPORT_LEVEL_ZERO)
+        message(STATUS "Level Zero loader found: ${ZE_LOADER_LIB}")
+        message(STATUS "Level Zero headers found: ${LEVEL_ZERO_INCLUDE_DIR}")
+    else()
+        message(WARNING "Level Zero loader or headers not found, Level Zero support disabled")
+    endif()
+endif()
+
 # Link against oneDNN
 set(GGML_SYCL_DNNL 0)
 if(GGML_SYCL_DNN)

ggml/src/ggml-sycl/common.cpp

@@ -11,6 +11,10 @@
 //
 
 #include "common.hpp"
+#include <sycl/backend.hpp>
+#ifdef GGML_SYCL_SUPPORT_LEVEL_ZERO
+#include <level_zero/ze_api.h>
+#endif
 
 #include "ggml-backend-impl.h"
 #include "ggml-impl.h"
@@ -55,6 +59,20 @@ bool gpu_has_xmx(sycl::device &dev) {
     return dev.has(sycl::aspect::ext_intel_matrix);
 }
 
+static int ggml_sycl_get_env(const char *env_name, int default_val) {
+    char *user_device_string = getenv(env_name);
+    int user_number = default_val;
+
+    unsigned n;
+    if (user_device_string != NULL &&
+        sscanf(user_device_string, " %u", &n) == 1) {
+        user_number = (int)n;
+    } else {
+        user_number = default_val;
+    }
+    return user_number;
+}
+
 int64_t downsample_sycl_global_range(int64_t accumulate_block_num, int64_t block_size) {
   const int64_t max_range = std::numeric_limits<int>::max();
   int64_t sycl_down_blk_size = block_size;
@@ -66,6 +84,61 @@ int64_t downsample_sycl_global_range(int64_t accumulate_block_num, int64_t block
   return sycl_down_blk_size;
 }
 
+#ifdef GGML_SYCL_SUPPORT_LEVEL_ZERO
+static bool ggml_sycl_use_level_zero_device_alloc(sycl::queue &q) {
+    return ggml_sycl_get_env("GGML_SYCL_ENABLE_LEVEL_ZERO", 1) &&
+        q.get_device().is_gpu() &&
+        q.get_backend() == sycl::backend::ext_oneapi_level_zero;
+}
+#endif
+
+// Use Level Zero zeMemAllocDevice to avoid sycl::malloc_device triggering
+// DMA-buf/TTM system RAM staging in the xe kernel driver during multi-GPU inference.
+// The decision is made from the queue and runtime env because large buffers can be
+// allocated before ggml_check_sycl() initializes g_ggml_sycl_enable_level_zero.
+void * ggml_sycl_malloc_device(size_t size, sycl::queue &q) {
+#ifdef GGML_SYCL_SUPPORT_LEVEL_ZERO
+    if (ggml_sycl_use_level_zero_device_alloc(q)) {
+        void *ptr = nullptr;
+        auto ze_ctx = sycl::get_native<sycl::backend::ext_oneapi_level_zero>(q.get_context());
+        auto ze_dev = sycl::get_native<sycl::backend::ext_oneapi_level_zero>(q.get_device());
+#ifdef ZE_RELAXED_ALLOCATION_LIMITS_EXP_NAME
+        ze_relaxed_allocation_limits_exp_desc_t relaxed_desc = {
+            ZE_STRUCTURE_TYPE_RELAXED_ALLOCATION_LIMITS_EXP_DESC,
+            nullptr,
+            ZE_RELAXED_ALLOCATION_LIMITS_EXP_FLAG_MAX_SIZE,
+        };
+        ze_device_mem_alloc_desc_t alloc_desc = {
+            ZE_STRUCTURE_TYPE_DEVICE_MEM_ALLOC_DESC,
+            &relaxed_desc,
+            0,
+            0,
+        };
+#else
+        ze_device_mem_alloc_desc_t alloc_desc = {ZE_STRUCTURE_TYPE_DEVICE_MEM_ALLOC_DESC, nullptr, 0, 0};
+#endif
+        ze_result_t r = zeMemAllocDevice(ze_ctx, &alloc_desc, size, 64, ze_dev, &ptr);
+        if (r == ZE_RESULT_SUCCESS && ptr) {
+            return ptr;
+        }
+        return nullptr;
+    }
+#endif
+    return sycl::malloc_device(size, q);
+}
+
+void ggml_sycl_free_device(void *ptr, sycl::queue &q) {
+    if (!ptr) return;
+#ifdef GGML_SYCL_SUPPORT_LEVEL_ZERO
+    if (ggml_sycl_use_level_zero_device_alloc(q)) {
+        auto ze_ctx = sycl::get_native<sycl::backend::ext_oneapi_level_zero>(q.get_context());
+        zeMemFree(ze_ctx, ptr);
+        return;
+    }
+#endif
+    SYCL_CHECK(CHECK_TRY_ERROR(sycl::free(ptr, q)));
+}
+
 void release_extra_gpu(ggml_tensor_extra_gpu * extra, std::vector<queue_ptr> streams) {
     for (int i = 0; i < ggml_sycl_info().device_count; ++i) {
         for (int64_t is = 0; is < GGML_SYCL_MAX_STREAMS; ++is) {
@@ -75,8 +148,7 @@ void release_extra_gpu(ggml_tensor_extra_gpu * extra, std::vector<queue_ptr> str
         }
         if (extra->data_device[i] != nullptr && streams.size()>0) {
             ggml_sycl_set_device(i);
-            SYCL_CHECK(
-                CHECK_TRY_ERROR(sycl::free(extra->data_device[i], *(streams[i]))));
+            SYCL_CHECK(CHECK_TRY_ERROR(ggml_sycl_free_device(extra->data_device[i], *(streams[i]))));
         }
     }
     delete extra;

ggml/src/ggml-sycl/common.hpp

@@ -309,6 +309,10 @@ struct ggml_tensor_extra_gpu {
   optimize_feature optimized_feature;
 };
 
+extern int g_ggml_sycl_enable_level_zero;
+void * ggml_sycl_malloc_device(size_t size, sycl::queue &q);
+void ggml_sycl_free_device(void *ptr, sycl::queue &q);
+
 void release_extra_gpu(ggml_tensor_extra_gpu * extra, std::vector<queue_ptr> streams={});
 
 namespace sycl_ex = sycl::ext::oneapi::experimental;