Environment Variables
This document describes environment variables that are having effect on DPC++ compiler and runtime.
Controlling DPC++ runtime
| Environment variable | Values | Description |
|---|---|---|
ONEAPI_DEVICE_SELECTOR |
See below. | This device selection environment variable can be used to limit the choice of devices available when the SYCL-using application is run. Useful for limiting devices to a certain type (like GPUs or accelerators) or backends (like Level Zero or OpenCL). This device selection mechanism is replacing SYCL_DEVICE_FILTER . The ONEAPI_DEVICE_SELECTOR syntax is shared with OpenMP and also allows sub-devices to be chosen. See below. for a full description. |
SYCL_DEVICE_FILTER (deprecated) |
backend:device_type:device_num |
Please use ONEAPI_DEVICE_SELECTOR environment variable instead. See section SYCL_DEVICE_FILTER below for SYCL_DEVICE_FILTER description. |
SYCL_DEVICE_ALLOWLIST |
See below | Filter out devices that do not match the pattern specified. BackendName accepts host, opencl, level_zero or cuda. DeviceType accepts host, cpu, gpu or acc. DeviceVendorId accepts uint32_t in hex form (0xXYZW). DriverVersion, PlatformVersion, DeviceName and PlatformName accept regular expression. Special characters, such as parenthesis, must be escaped. DPC++ runtime will select only those devices which satisfy provided values above and regex. More than one device can be specified using the piping symbol "|". |
SYCL_DISABLE_PARALLEL_FOR_RANGE_ROUNDING |
Any(*) | Disables automatic rounding-up of parallel_for invocation ranges. |
SYCL_CACHE_DIR |
Path | Path to persistent cache root directory. Default values are %AppData%\libsycl_cache for Windows and $XDG_CACHE_HOME/libsycl_cache on Linux, if XDG_CACHE_HOME is not set then $HOME/.cache/libsycl_cache. When none of the environment variables are set SYCL persistent cache is disabled. |
SYCL_CACHE_DISABLE_PERSISTENT (deprecated) |
Any(*) | Has no effect. |
SYCL_CACHE_PERSISTENT |
Integer | Controls persistent device compiled code cache. Turns it on if set to '1' and turns it off if set to '0'. When cache is enabled SYCL runtime will try to cache and reuse JIT-compiled binaries. Default is off. |
SYCL_CACHE_EVICTION_DISABLE |
Any(*) | Switches cache eviction off when the variable is set. |
SYCL_CACHE_MAX_SIZE |
Positive integer | Cache eviction is triggered once total size of cached images exceeds the value in megabytes (default - 8 192 for 8 GB). Set to 0 to disable size-based cache eviction. |
SYCL_CACHE_THRESHOLD |
Positive integer | Cache eviction threshold in days (default value is 7 for 1 week). Set to 0 for disabling time-based cache eviction. |
SYCL_CACHE_MIN_DEVICE_IMAGE_SIZE |
Positive integer | Minimum size of device code image in bytes which is reasonable to cache on disk because disk access operation may take more time than do JIT compilation for it. Default value is 0 to cache all images. |
SYCL_CACHE_MAX_DEVICE_IMAGE_SIZE |
Positive integer | Maximum size of device image in bytes which is cached. Too big kernels may overload disk too fast. Default value is 1 GB. |
SYCL_ENABLE_DEFAULT_CONTEXTS |
'1' or '0' | Enable ('1') or disable ('0') creation of default platform contexts in SYCL runtime. The default context for each platform contains all devices in the platform. Refer to Platform Default Contexts extension to learn more. Enabled by default on Linux and disabled on Windows. |
SYCL_RT_WARNING_LEVEL |
Positive integer | The higher warning level is used the more warnings and performance hints the runtime library may print. Default value is '0', which means no warning/hint messages from the runtime library are allowed. The value '1' enables performance warnings from device runtime/codegen. The values greater than 1 are reserved for future use. |
SYCL_USM_HOSTPTR_IMPORT |
Integer | Enable by specifying non-zero value. Buffers created with a host pointer will result in host data promotion to USM, improving data transfer performance. To use this feature, also set SYCL_HOST_UNIFIED_MEMORY=1. |
SYCL_EAGER_INIT |
Integer | Enable by specifying non-zero value. Tells the SYCL runtime to do as much as possible initialization at objects construction as opposed to doing lazy initialization on the fly. This may mean doing some redundant work at warmup but ensures fastest possible execution on the following hot and reportable paths. It also instructs PI plugins to do the same. Default is "0". |
SYCL_REDUCTION_PREFERRED_WORKGROUP_SIZE |
See below | Controls the preferred work-group size of reductions. |
SYCL_ENABLE_FUSION_CACHING |
'1' or '0' | Enable ('1') or disable ('0') caching of JIT compilations for kernel fusion. Caching avoids repeatedly running the JIT compilation pipeline if the same sequence of kernels is fused multiple times. Default value is '1'. |
(*) Note: Any means this environment variable is effective when set to any non-null value.
ONEAPI_DEVICE_SELECTOR
With no environment variables set to say otherwise, all platforms and devices presently on the machine are available. The default choice will be one of these devices, usually preferring a Level Zero GPU device, if available. The ONEAPI_DEVICE_SELECTOR can be used to limit that choice of devices, and to expose GPU sub-devices or sub-sub-devices as individual devices.
The syntax of this environment variable follows this BNF grammar:
ONEAPI_DEVICE_SELECTOR = <selector-string>
<selector-string> ::= { <accept-filters> | <discard-filters> | <accept-filters>;<discard-filters> }
<accept-filters> ::= <accept-filter>[;<accept-filter>...]
<discard-filters> ::= <discard-filter>[;<discard-filter>...]
<accept-filter> ::= <term>
<discard-filter> ::= !<term>
<term> ::= <backend>:<devices>
<backend> ::= { * | level_zero | opencl | cuda | hip | esimd_emulator } // case insensitive
<devices> ::= <device>[,<device>...]
<device> ::= { * | cpu | gpu | fpga | <num> | <num>.<num> | <num>.* | *.* | <num>.<num>.<num> | <num>.<num>.* | <num>.*.* | *.*.* } // case insensitive
Each term in the grammar selects a collection of devices from a particular backend. The device names cpu, gpu, and fpga select all devices from that backend with the corresponding type. A backend's device can also be selected by its numeric index (zero-based) or by using * which selects all devices in the backend.
The dot syntax (e.g. <num>.<num>) causes one or more GPU sub-devices to be exposed to the application as SYCL root devices. For example, 1.0 exposes the first sub-device of the second device as a SYCL root device. The syntax <num>.* exposes all sub-devices of the give device as SYCL root devices. The syntax *.* exposes all sub-devices of all GPU devices as SYCL root devices.
In general, a term with one or more asterisks ( * ) matches all backends, devices, or sub-devices with the given pattern. However, a warning is generated if the term does not match anything. For example, *:gpu matches all GPU devices in all backends (ignoring backends with no GPU devices), but it generates a warning if there are no GPU devices in any backend. Likewise, level_zero:*.* matches all sub-devices of partitionable GPUs in the Level Zero backend, but it generates a warning if there are no Level Zero GPU devices that are partitionable into sub-devices.
The device indices are zero-based and are unique only within a backend. Therefore, level_zero:0 is a different device from cuda:0. To see the indices of all available devices, run the sycl-ls tool. Note that different backends sometimes expose the same hardware as different "devices". For example, the level_zero and opencl backends both expose the Intel GPU devices.
Additionally, if a sub-device is chosen (via numeric index or wildcard), then an additional layer of partitioning can be specified. In other words, a sub-sub-device can be selected. Like sub-devices, this is done with a period ( . ) and a sub-sub-device specifier which is a wildcard symbol ( * ) or a numeric index. Example ONEAPI_DEVICE_SELECTOR=level_zero:0.*.* would partition device 0 into sub-devices and then partition each of those into sub-sub-devices. The range of grandchild sub-sub-devices would be the final devices available to the app, neither device 0, nor its child partitions would be in that list.
Lastly, a filter in the grammar can be thought of as a term in conjuction with an action that is taken on all devices that are selected by the term. The action can be an accept action or a discard action. Based on the action, a filter can be an accept filter or a discard filter.
The string <term> represents an accept filter and the string !<term> represents a discard filter. The underlying term is the same but they perform different actions on the matching devices list.
For example, !opencl:* discards all devices of the opencl backend from the list of available devices. The discarding filters, if there are any, must all appear at the end of the selector string.
When one or more filters accept a device and one or more filters discard the device, the latter have priority and the device is ultimately not made available to the user. This allows the user to provide selector strings such as *:gpu;!cuda:* that accepts all gpu devices except those with a CUDA backend.
Furthermore, if the value of this environment variable only has discarding filters, an accepting filter that matches all devices, but not sub-devices and sub-sub-devices, will be implicitly included in the
environment variable to allow the user to specify only the list of devices that must not be made available. Therefore, !*:cpu will accept all devices except those that are of the cpu type and opencl:*;!*:cpu
will accept all devices of the opencl backend exept those that are of the opencl backend and of the cpu type. It is legal to have a rejection filter even if it specifies devices have already been omitted by previous filters in the selection string. Doing so has no effect; the rejected devices are still omitted.
The following examples further illustrate the usage of this environment variable:
| Example | Result |
|---|---|
ONEAPI_DEVICE_SELECTOR=opencl:* |
Only the OpenCL devices are available |
ONEAPI_DEVICE_SELECTOR=level_zero:gpu |
Only GPU devices on the Level Zero platform are available. |
ONEAPI_DEVICE_SELECTOR="opencl:gpu;level_zero:gpu" |
GPU devices from both Level Zero and OpenCL are available. Note that escaping (like quotation marks) will likely be needed when using semi-colon separated entries. |
ONEAPI_DEVICE_SELECTOR=opencl:gpu,cpu |
Only CPU and GPU devices on the OpenCL platform are available. |
ONEAPI_DEVICE_SELECTOR=opencl:0 |
Only the device with index 0 on the OpenCL backend is available. |
ONEAPI_DEVICE_SELECTOR=hip:0,2 |
Only devices with indices of 0 and 2 from the HIP backend are available. |
ONEAPI_DEVICE_SELECTOR=opencl:0.* |
All the sub-devices from the OpenCL device with index 0 are exposed as SYCL root devices. No other devices are available. |
ONEAPI_DEVICE_SELECTOR=opencl:0.2 |
The third sub-device (2 in zero-based counting) of the OpenCL device with index 0 will be the sole device available. |
ONEAPI_DEVICE_SELECTOR=level_zero:*,*.* |
Exposes Level Zero devices to the application in two different ways. Each device (aka "card") is exposed as a SYCL root device and each sub-device is also exposed as a SYCL root device. |
ONEAPI_DEVICE_SELECTOR="opencl:*;!opencl:0" |
All OpenCL devices except for the device with index 0 are available. |
ONEAPI_DEVICE_SELECTOR="!*:cpu" |
All devices except for CPU devices are available. |
Notes:
- The backend argument is always required. An error will be thrown if it is absent.
- Additionally, the backend MUST be followed by colon (
:) and at least one device specifier of some sort, else an error is thrown. - For sub-devices and sub-sub-devices, the parent device must support partitioning (
info::partition_property::partition_by_affinity_domainandinfo::partition_affinity_domain::next_partitionable. See the SYCL 2020 specification for a precise definition.) For Intel GPUs, the sub-device and sub-sub-device syntax can be used to expose tiles or CCSs to the SYCL application as root devices. The exact mapping between sub-device, sub-sub-device, tiles, and CCSs is specific to the hardware. - The semi-colon character (
;) and the exclamation mark character (!) are treated specially by many shells, so you may need to enclose the string in quotes if the selection string contains these characters.
SYCL_DEVICE_ALLOWLIST
A list of devices and their driver version following the pattern:
BackendName:XXX,DeviceType:YYY,DeviceVendorId:0xXYZW,DriverVersion:{{X.Y.Z.W}}.
Also may contain PlatformVersion, DeviceName and PlatformName. There is no
fixed order of properties in the pattern.
SYCL_DEVICE_FILTER
This environment variable limits the SYCL RT to use only a subset of the system's devices. Setting this environment variable affects all of the device query functions (platform::get_devices() and platform::get_platforms()) and all of the device selectors.
The value of this environment variable is a comma separated list of filters, where each filter is a triple of the form "backend:device_type:device_num" (without the quotes). Each element of the triple is optional, but each filter must have at least one value. Possible values of backend are:
host(Deprecated)level_zeroopenclcudahipesimd_emulator*
Possible values of device_type are:
host(Deprecated)cpugpuacc*
device_num is an integer that indexes the enumeration of devices from the sycl-ls utility tool, where the first device in that enumeration has index zero in each backend. For example, SYCL_DEVICE_FILTER=2 will return all devices with index '2' from all different backends. If multiple devices satisfy this device number (e.g., GPU and CPU devices can be assigned device number '2'), then default_selector will choose the device with the highest heuristic point. When SYCL_DEVICE_ALLOWLIST is set, it is applied before enumerating devices and affects device_num values.
Assuming a filter has all three elements of the triple, it selects only those devices that come from the given backend, have the specified device type, AND have the given device index. If more than one filter is specified, the RT is restricted to the union of devices selected by all filters.
Note that all device selectors will throw an exception if the filtered list of devices does not include a device that satisfies the selector. For instance, SYCL_DEVICE_FILTER=cpu will cause gpu_selector() to throw an exception. SYCL_DEVICE_FILTER also limits loading only specified plugins into the SYCL RT. In particular, SYCL_DEVICE_FILTER=level_zero will cause the cpu_selector to throw an exception since SYCL RT will only load the level_zero backend which does not support any CPU devices at this time. When multiple devices satisfy the filter (e..g, SYCL_DEVICE_FILTER=gpu), only one of them will be selected.
SYCL_REDUCTION_PREFERRED_WORKGROUP_SIZE
This environment variable controls the preferred work-group size for reductions on specified device types. Setting this will affect all reductions without an explicitly specified work-group size on devices of types in the value of the environment variable.
The value of this environment variable is a comma separated list of one or more configurations, where each configuration is a pair of the form "device_type:size" (without the quotes). Possible values of device_type are:
cpugpuacc*
size is a positive integer larger than 0.
For a configuration device_type:size the device_type element specifies the type of device the configuration applies to, that is cpu is for CPU devices, gpu is for GPU devices, and acc is for accelerator devices. If device_type is * the configuration applies to all applicable device types. size denotes the preferred work-group size to be used for devices of types specified by device_type.
If info::device::max_work_group_size on a device on which a reduction is being enqueued is less than the value specified by a configuration in this environment variable, the value of info::device::max_work_group_size on that device is used instead.
A sycl::exception with sycl::errc::invalid is thrown during submission of a reduction kernel in the following cases:
- If the specified device type in any configuration is not one of the valid values.
- If the specified preferred work-group size in any configuration is not a valid integer.
- If the specified preferred work-group size in any configuration is not an integer value larger than 0.
- If any configuration does not have the
:delimiter.
If this environment variable is not set, the preferred work-group size for reductions is implementation defined.
Note that conflicting configuration tuples in the same list will favor the last entry. For example, a list cpu:32,gpu:32,cpu:16 will set the preferred work-group size of reductions to 32 for GPUs and 16 for CPUs. This also applies to *, for example cpu:32,*:16 sets the preferred work-group size of reductions on all devices to 16, while *:16,cpu:32 sets the preferred work-group size of reductions to 32 on CPUs and to 16 on all other devices.
Controlling DPC++ Level Zero Plugin
| Environment variable | Values | Description |
|---|---|---|
SYCL_ENABLE_PCI |
Integer | When set to 1, enables obtaining the GPU PCI address when using the Level Zero backend. The default is 0. |
SYCL_PI_LEVEL_ZERO_DISABLE_USM_ALLOCATOR |
Any(*) | Disable USM allocator in Level Zero plugin (each memory request will go directly to Level Zero runtime) |
SYCL_PI_LEVEL_ZERO_TRACK_INDIRECT_ACCESS_MEMORY |
Any(*) | Enable support of the kernels with indirect access and corresponding deferred release of memory allocations in the Level Zero plugin. |
(*) Note: Any means this environment variable is effective when set to any non-null value.
Controlling DPC++ CUDA Plugin
| Environment variable | Values | Description |
|---|---|---|
SYCL_PI_CUDA_MAX_LOCAL_MEM_SIZE |
Integer | Specifies the maximum size of a local memory allocation in bytes. If the value exceeds the device's capabilities then a sycl::runtime_error is thrown. In order for the full error message to be printed, SYCL_RT_WARNING_LEVEL=2 must be set. The default value for SYCL_PI_CUDA_MAX_LOCAL_MEM_SIZE is determined by the hardware. |
Controlling DPC++ HIP Plugin
| Environment variable | Values | Description |
|---|---|---|
SYCL_PI_HIP_MAX_LOCAL_MEM_SIZE |
Integer | Specifies the maximum size of a local memory allocation in bytes. If the value exceeds the device's capabilities then a sycl::runtime_error is thrown. In order for the full error message to be printed, SYCL_RT_WARNING_LEVEL=2 must be set. The default value for SYCL_PI_HIP_MAX_LOCAL_MEM_SIZE is determined by the hardware. |
Tools variables
| Environment variable | Values | Description |
|---|---|---|
INTEL_ENABLE_OFFLOAD_ANNOTATIONS |
Any(*) | Enables ITT Annotations support for SYCL runtime. This variable should only be used by tools, that support ITT Annotations. |
XPTI_FRAMEWORK_DISPATCHER(**) |
Path to dispatcher library | Loads XPTI instrumentation dispatcher framework library. See XPTI Framework documentation for more info |
XPTI_TRACE_ENABLE(**) |
1, true, 0, false |
Enables XPTI instrumentation. See XPTI Framework documentation for more info |
XPTI_SUBSCRIBERS(**) |
Comma separated list of subscriber libraries | Loads XPTI subscribers. See XPTI Framework documentation for more info |
(*) Note: Any means this environment variable is effective when set to any non-null value.
(**) Note: These variables come from XPTI framework
Debugging variables for DPC++ Runtime
| Environment variable | Values | Description |
|---|---|---|
SYCL_PI_TRACE |
Described below | Enable specified level of tracing for PI. |
SYCL_QUEUE_THREAD_POOL_SIZE |
Positive integer | Number of threads in thread pool of queue. |
SYCL_DEVICELIB_NO_FALLBACK |
Any(*) | Disable loading and linking of device library images |
SYCL_PRINT_EXECUTION_GRAPH |
Described below | Print execution graph to DOT text file. |
SYCL_DISABLE_EXECUTION_GRAPH_CLEANUP |
Any(*) | Disable cleanup of finished command nodes at host-device synchronization points. |
SYCL_DISABLE_POST_ENQUEUE_CLEANUP |
Any(*) | Disable cleanup of enqueued command nodes during submission. |
SYCL_DEVICELIB_INHIBIT_NATIVE |
String of device library extensions (separated by a whitespace) | Do not rely on device native support for devicelib extensions listed in this option. |
SYCL_PROGRAM_COMPILE_OPTIONS |
String of valid OpenCL compile options | Override compile options for all programs. |
SYCL_PROGRAM_LINK_OPTIONS |
String of valid OpenCL link options | Override link options for all programs. |
SYCL_USE_KERNEL_SPV |
Path to the SPIR-V binary | Load device image from the specified file. If runtime is unable to read the file, sycl::runtime_error exception is thrown. |
SYCL_DUMP_IMAGES |
Any(*) | Dump device image binaries to file. Control has no effect if SYCL_USE_KERNEL_SPV is set. |
SYCL_HOST_UNIFIED_MEMORY |
Integer | Enforce host unified memory support or lack of it for the execution graph builder. If set to 0, it is enforced as not supported by all devices. If set to 1, it is enforced as supported by all devices. |
SYCL_CACHE_TRACE |
Any(*) | If the variable is set, messages are sent to std::cerr when caching events or non-blocking failures happen (e.g. unable to access cache item file). |
SYCL_PARALLEL_FOR_RANGE_ROUNDING_TRACE |
Any(*) | Enables tracing of parallel_for invocations with rounded-up ranges. |
SYCL_PI_SUPPRESS_ERROR_MESSAGE |
Any(*) | Suppress printing of error message, only used for CI in order not to interrupt errors generated by underlying toolchains; note that the variable only modifies the printing of the error message (error value, name, description and location), the handling of error return code and aborting/throwing behaviour remains unchanged. |
(*) Note: Any means this environment variable is effective when set to any non-null value.
SYCL_PRINT_EXECUTION_GRAPH Options
SYCL_PRINT_EXECUTION_GRAPH can accept one or more comma separated values from the table below
| Option | Description |
|---|---|
| before_addCG | print graph before addCG method |
| after_addCG | print graph after addCG method |
| before_addCopyBack | print graph before addCopyBack method |
| after_addCopyBack | print graph after addCopyBack method |
| before_addHostAcc | print graph before addHostAccessor method |
| after_addHostAcc | print graph after addHostAccessor method |
| always | print graph before and after each of the above methods |
SYCL_PI_TRACE Options
SYCL_PI_TRACE accepts a bit-mask. Supported tracing levels are in the table below
| Option | Description |
|---|---|
| 1 | Enable basic tracing, which is tracing of PI plugins/devices discovery |
| 2 | Enable tracing of the PI calls |
| -1 | Enable all levels of tracing |
Debugging variables for Level Zero Plugin
| Environment variable | Values | Description |
|---|---|---|
SYCL_PI_LEVEL_ZERO_SINGLE_THREAD_MODE |
Integer | A single-threaded app has an opportunity to enable this mode to avoid overhead from mutex locking in the Level Zero plugin. A value greater than 0 enables single thread mode. A value of 0 disables single thread mode. The default is 0. |
SYCL_PI_LEVEL_ZERO_USM_ALLOCATOR |
[EnableBuffers][;[MaxPoolSize][;[host|device|shared:][MaxPoolableSize][,[Capacity][,SlabMinSize]]]...] | EnableBuffers enables pooling for SYCL buffers, default 0, set to 1 to enable. MaxPoolSize is the maximum size of the pool, default 0. MemType is host, device or shared. Other parameters are values specified as positive integers with optional K, M or G suffix. MaxPoolableSize is the maximum allocation size that may be pooled, default 0 for host and shared, 32KB for device. Capacity is the number of allocations in each size range freed by the program but retained in the pool for reallocation, default 0. Size ranges follow this pattern: 64, 96, 128, 192, and so on, i.e., powers of 2, with one range in between. SlabMinSize is the minimum allocation size, 64KB for host and device, 2MB for shared. Example: SYCL_PI_LEVEL_ZERO_USM_ALLOCATOR=1;32M;host:1M,4,64K;device:1M,4,64K;shared:0,0,2M |
SYCL_PI_LEVEL_ZERO_BATCH_SIZE |
Integer | Sets a preferred number of compute commands to batch into a command list before executing the command list. A value of 0 causes the batch size to be adjusted dynamically. A value greater than 0 specifies fixed size batching, with the batch size set to the specified value. The default is 0. |
SYCL_PI_LEVEL_ZERO_COPY_BATCH_SIZE |
Integer | Sets a preferred number of copy commands to batch into a command list before executing the command list. A value of 0 causes the batch size to be adjusted dynamically. A value greater than 0 specifies fixed size batching, with the batch size set to the specified value. The default is 0. |
SYCL_PI_LEVEL_ZERO_FILTER_EVENT_WAIT_LIST |
Integer | When set to 0, disables filtering of signaled events from wait lists when using the Level Zero backend. The default is 0. |
SYCL_PI_LEVEL_ZERO_USE_COPY_ENGINE |
Any(*) | This environment variable enables users to control use of copy engines for copy operations. If the value is an integer, it will allow the use of copy engines, if available in the device, in Level Zero plugin to transfer SYCL buffer or image data between the host and/or device(s) and to fill SYCL buffer or image data in device or shared memory. The value of this environment variable can also be a pair of the form "lower_index:upper_index" where the indices point to copy engines in a list of all available copy engines. The default is 1. |
SYCL_PI_LEVEL_ZERO_USE_COMPUTE_ENGINE |
Integer | It can be set to an integer (>=0) in which case all compute commands will be submitted to the command-queue with the given index in the compute command group. If it is instead set to a negative value then all available compute engines may be used. The default value is "0" |
SYCL_PI_LEVEL_ZERO_USE_COPY_ENGINE_FOR_D2D_COPY (experimental) |
Integer | Allows the use of copy engine, if available in the device, in Level Zero plugin for device to device copy operations. The default is 0. This option is experimental and will be removed once heuristics are added to make a decision about use of copy engine for device to device copy operations. |
SYCL_PI_LEVEL_ZERO_DEVICE_SCOPE_EVENTS |
Any(*) | Enable support of device-scope events whose state is not visible to the host. If enabled mode is SYCL_PI_LEVEL_ZERO_DEVICE_SCOPE_EVENTS=1 the Level Zero plugin would create all events having device-scope only and create proxy host-visible events for them when their status is needed (wait/query) on the host. If enabled mode is SYCL_PI_LEVEL_ZERO_DEVICE_SCOPE_EVENTS=2 the Level Zero plugin would create all events having device-scope and add proxy host-visible event at the end of each command-list submission. The default is 0, meaning all events have host visibility. SYCL_PI_LEVEL_ZERO_DEVICE_SCOPE_EVENTS is ignored when using immediate command lists (SYCL_PI_LEVEL_ZERO_USE_IMMEDIATE_COMMANDLISTS = 1) and all events use default scope of 0. |
SYCL_PI_LEVEL_ZERO_USE_IMMEDIATE_COMMANDLISTS |
Integer | When set to a positive value enables use of Level Zero immediate commandlists, which means there is no batching and all commands are immediately submitted for execution. When set to 1, unique immediate commandlists are created for each SYCL queue. When set to 2, unique immediate commandlists are created per host thread per SYCL queue. Default is 0. |
SYCL_PI_LEVEL_ZERO_USE_MULTIPLE_COMMANDLIST_BARRIERS |
Integer | When set to a positive value enables use of multiple Level Zero commandlists when submitting barriers. Default is 1. |
SYCL_PI_LEVEL_ZERO_USE_COPY_ENGINE_FOR_FILL |
Integer | When set to a positive value enables use of a copy engine for memory fill operations. Default is 0. |
SYCL_PI_LEVEL_ZERO_SINGLE_ROOT_DEVICE_BUFFER_MIGRATION |
Integer | When set to "0" tells to use single root-device allocation for all devices in a context where all devices have same root. Otherwise performs regular buffer migration. Default is 1. |
SYCL_PI_LEVEL_ZERO_REUSE_DISCARDED_EVENTS |
Integer | When set to a positive value enables the mode when discarded Level Zero events are reset and reused in scope of the same in-order queue based on the dependency chain between commands. Default is 1. |
SYCL_PI_LEVEL_ZERO_EXPOSE_CSLICE_IN_AFFINITY_PARTITIONING (Deprecated) |
Integer | When set to non-zero value exposes compute slices as sub-sub-devices in sycl::info::partition_property::partition_by_affinity_domain partitioning scheme. Default is zero meaning that they are only exposed when partitioning by sycl::info::partition_property::ext_intel_partition_by_cslice. This option is introduced for compatibility reasons and is immediately deprecated. New code must not rely on this behavior. Also note that even if sub-sub-device was created using partition_by_affinity_domain it would still be reported as created via partitioning by compute slices. |
SYCL_PI_LEVEL_ZERO_IMMEDIATE_COMMANDLISTS_EVENT_CLEANUP_THRESHOLD |
Integer | If non-negative then the threshold is set to this value. If negative, the threshold is set to INT_MAX. Whenever the number of events associated with an immediate command list exceeds this threshold, a check is made for signaled events and these events are recycled. Setting this threshold low causes events to be checked more often, which could result in unneeded events being recycled sooner. However, more frequent event status checks may cost time. The default is 20. |
SYCL_PI_LEVEL_ZERO_USM_RESIDENT |
Integer | Controls if/where to make USM allocations resident at the time of allocation. If set to 0 (default) then no special residency is forced. If set to 1 then allocation (device or shared) is made resident at the device of allocation. If set to 2 then allocation (device or shared) is made resident on all devices in the context of allocation that have P2P access to the device of allocation. For host allocation, any non-0 setting forces the allocation resident on all devices in the context. |
SYCL_PI_LEVEL_ZERO_USE_NATIVE_USM_MEMCPY2D |
Integer | When set to a positive value enables the use of Level Zero USM 2D memory copy operations. Default is 0. |
Debugging variables for CUDA Plugin
| Environment variable | Values | Description |
|---|---|---|
SYCL_PI_CUDA_ENABLE_IMAGE_SUPPORT (experimental) |
Any(*) | Enable support of images. This option is experimental since the image support is not fully implemented. |
(*) Note: Any means this environment variable is effective when set to any non-null value.