ROCprofiler-SDK callback tracing services#
Callback tracing services provide immediate callbacks to a tool on the current CPU thread on the occurrence of an event.
For example, when tracing an API function such as hipSetDevice, callback tracing invokes a user-specified callback
before and after the traced function executes on the thread invoking the API function.
Subscribing to callback tracing services#
During tool initialization, tools configure callback tracing using:
rocprofiler_status_t
rocprofiler_configure_callback_tracing_service(rocprofiler_context_id_t context_id,
rocprofiler_callback_tracing_kind_t kind,
rocprofiler_tracing_operation_t* operations,
size_t operations_count,
rocprofiler_callback_tracing_cb_t callback,
void* callback_args);
Here are the parameters required to configure callback tracing services:
kind: A high-level specification of the services to be traced. This parameter is also known as “domain”. Domain examples include, but not limited to, the HIP API, HSA API, and kernel dispatches.operations: For each domain, there are often variousoperationsthat can be used to restrict the callbacks to a subset within the domain. For domains corresponding to APIs, theoperationsare the functions composing the API. To trace all operations in a domain, set theoperationsandoperations_countparameters tonullptrand0respectively. To restrict the tracing domain to a subset of operations, the tool library must specify a C-array of typerocprofiler_tracing_operation_tforoperationsand size of the array for theoperations_countparameter.
rocprofiler_configure_callback_tracing_service returns an error if a callback service for the specified context and domain is configured more than once.
Example: To trace only two functions within
the HIP runtime API, hipGetDevice and hipSetDevice:
{
auto ctx = rocprofiler_context_id_t{};
// ... creation of context, etc. ...
// array of operations (i.e. API functions)
auto operations = std::array<rocprofiler_tracing_operation_t, 2>{
ROCPROFILER_HIP_RUNTIME_API_ID_hipSetDevice,
ROCPROFILER_HIP_RUNTIME_API_ID_hipGetDevice
};
rocprofiler_configure_callback_tracing_service(ctx,
ROCPROFILER_CALLBACK_TRACING_HIP_RUNTIME_API,
operations.data(),
operations.size(),
callback_func,
nullptr);
// ... etc. ...
}
The following code returns error ROCPROFILER_STATUS_ERROR_SERVICE_ALREADY_CONFIGURED as the callback service is already configured:
{
auto ctx = rocprofiler_context_id_t{};
// ... creation of context, etc. ...
// array of operations (i.e. API functions)
auto operations = std::array<rocprofiler_tracing_operation_t, 2>{
ROCPROFILER_HIP_RUNTIME_API_ID_hipSetDevice,
ROCPROFILER_HIP_RUNTIME_API_ID_hipGetDevice
};
for(auto op : operations)
{
// after the first iteration, returns ROCPROFILER_STATUS_ERROR_SERVICE_ALREADY_CONFIGURED
rocprofiler_configure_callback_tracing_service(ctx,
ROCPROFILER_CALLBACK_TRACING_HIP_RUNTIME_API,
&op,
1,
callback_func,
nullptr);
}
// ... etc. ...
}
Callback tracing callback function#
Here is the callback tracing callback function:
typedef void (*rocprofiler_callback_tracing_cb_t)(rocprofiler_callback_tracing_record_t record,
rocprofiler_user_data_t* user_data,
void* callback_data)
The parameters record and user_data are discussed here:
record: Contains the information to uniquely identify a tracing record type. Here is the definition:typedef struct rocprofiler_callback_tracing_record_t { rocprofiler_context_id_t context_id; rocprofiler_thread_id_t thread_id; rocprofiler_correlation_id_t correlation_id; rocprofiler_callback_tracing_kind_t kind; uint32_t operation; rocprofiler_callback_phase_t phase; void* payload; } rocprofiler_callback_tracing_record_t;
The underlying type of
payloadfield is typically unique to a domain and, less frequently, an operation. For example, for theROCPROFILER_CALLBACK_TRACING_HIP_RUNTIME_APIandROCPROFILER_CALLBACK_TRACING_HIP_COMPILER_API, the payload must be casted torocprofiler_callback_tracing_hip_api_data_t*, which contains the arguments to the function and the return value when exiting the function. The payload field is a valid pointer only during the invocation of the callback function(s).user_data: Stores data in between callback phases. This value is unique for every instance of an operation. For example, for a tool library to store the timestamp of theROCPROFILER_CALLBACK_PHASE_ENTERphase for the ensuingROCPROFILER_CALLBACK_PHASE_EXITcallback, the data can be stored using:void callback_func(rocprofiler_callback_tracing_record_t record, rocprofiler_user_data_t* user_data, void* cb_data) { auto ts = rocprofiler_timestamp_t{}; rocprofiler_get_timestamp(&ts); if(record.phase == ROCPROFILER_CALLBACK_PHASE_ENTER) { user_data->value = ts; } else if(record.phase == ROCPROFILER_CALLBACK_PHASE_EXIT) { auto delta_ts = (ts - user_data->value); // ... etc. ... } else { // ... etc. ... } }
The
callback_datais passed torocprofiler_configure_callback_tracing_serviceas the value ofcallback_argsto subscribe to callback tracing services.
Callback tracing record#
To obtain the name of the kind of tracing, you can use rocprofiler_query_callback_tracing_kind_name function and to obtain the name of an operation specific to a tracing kind, use rocprofiler_query_callback_tracing_kind_operation_name
function. To iterate over all the callback tracing kinds and operations for each tracing kind, use rocprofiler_iterate_callback_tracing_kinds and rocprofiler_iterate_callback_tracing_kind_operations functions.
Lastly, for a specified rocprofiler_callback_tracing_record_t object, ROCprofiler-SDK supports generically iterating over the arguments of the payload field for many domains. Within the rocprofiler_callback_tracing_record_t object, the domain-specific information is available in
an opaque void* payload.
The data types generally follow the naming convention of rocprofiler_callback_tracing_<DOMAIN>_data_t. For example, for the tracing kinds ROCPROFILER_BUFFER_TRACING_HSA_{CORE,AMD_EXT,IMAGE_EXT,FINALIZE_EXT}_API,
cast the payload to rocprofiler_callback_tracing_hsa_api_data_t*:
void
callback_func(rocprofiler_callback_tracing_record_t record,
rocprofiler_user_data_t* user_data,
void* cb_data)
{
static auto hsa_domains = std::unordered_set<rocprofiler_buffer_tracing_kind_t>{
ROCPROFILER_BUFFER_TRACING_HSA_CORE_API,
ROCPROFILER_BUFFER_TRACING_HSA_AMD_EXT_API,
ROCPROFILER_BUFFER_TRACING_HSA_IMAGE_EXT_API,
ROCPROFILER_BUFFER_TRACING_HSA_FINALIZER_API};
if(hsa_domains.count(record.kind) > 0)
{
auto* payload = static_cast<rocprofiler_callback_tracing_hsa_api_data_t*>(record.payload);
hsa_status_t status = payload->retval.hsa_status_t_retval;
if(record.phase == ROCPROFILER_CALLBACK_PHASE_EXIT && status != HSA_STATUS_SUCCESS)
{
const char* _kind = nullptr;
const char* _operation = nullptr;
rocprofiler_query_callback_tracing_kind_name(record.kind, &_kind, nullptr);
rocprofiler_query_callback_tracing_kind_operation_name(
record.kind, record.operation, &_operation, nullptr);
// message that
fprintf(stderr, "[domain=%s] %s returned a non-zero exit code: %i\n", _kind, _operation, status);
}
}
else if(record.phase == ROCPROFILER_CALLBACK_PHASE_EXIT)
{
auto delta_ts = (ts - user_data->value);
// ... etc. ...
}
else
{
// ... etc. ...
}
}
Example: Iterating over all the callback tracing kinds and operations for each tracing kind using rocprofiler_iterate_callback_tracing_kind_operation_args:
int
print_args(rocprofiler_callback_tracing_kind_t domain_idx,
uint32_t op_idx,
uint32_t arg_num,
const void* const arg_value_addr,
int32_t arg_indirection_count,
const char* arg_type,
const char* arg_name,
const char* arg_value_str,
int32_t arg_dereference_count,
void* data)
{
if(arg_num == 0)
{
const char* _kind = nullptr;
const char* _operation = nullptr;
rocprofiler_query_callback_tracing_kind_name(domain_idx, &_kind, nullptr);
rocprofiler_query_callback_tracing_kind_operation_name(
domain_idx, op_idx, &_operation, nullptr);
fprintf(stderr, "\n[%s] %s\n", _kind, _operation);
}
char* _arg_type = abi::__cxa_demangle(arg_type, nullptr, nullptr, nullptr);
fprintf(stderr, " %u: %-18s %-16s = %s\n", arg_num, _arg_type, arg_name, arg_value_str);
free(_arg_type);
// unused in example
(void) arg_value_addr;
(void) arg_indirection_count;
(void) arg_dereference_count;
(void) data;
return 0;
}
void
callback_func(rocprofiler_callback_tracing_record_t record,
rocprofiler_user_data_t* user_data,
void* cb_data)
{
if(record.phase == ROCPROFILER_CALLBACK_PHASE_EXIT &&
record.kind == ROCPROFILER_CALLBACK_TRACING_HIP_RUNTIME_API &&
(record.operation == ROCPROFILER_HIP_RUNTIME_API_ID_hipLaunchKernel ||
record.operation == ROCPROFILER_HIP_RUNTIME_API_ID_hipMemcpyAsync))
{
rocprofiler_iterate_callback_tracing_kind_operation_args(
record, print_args, record.phase, nullptr));
}
}
Sample output:
[HIP_RUNTIME_API] hipLaunchKernel
0: void const* function_address = 0x219308
1: rocprofiler_dim3_t numBlocks = {z=1, y=310, x=310}
2: rocprofiler_dim3_t dimBlocks = {z=1, y=32, x=32}
3: void** args = 0x7ffe6d8dd3c0
4: unsigned long sharedMemBytes = 0
5: hipStream_t* stream = 0x17b40c0
[HIP_RUNTIME_API] hipMemcpyAsync
0: void* dst = 0x7f06c7bbb010
1: void const* src = 0x7f0698800000
2: unsigned long sizeBytes = 393625600
3: hipMemcpyKind kind = DeviceToHost
4: hipStream_t* stream = 0x25dfcf0
Code object tracing#
The code object tracing service is a critical component for obtaining information regarding
asynchronous activity on the GPU. The rocprofiler_callback_tracing_code_object_load_data_t
payload (kind=ROCPROFILER_CALLBACK_TRACING_CODE_OBJECT, operation=ROCPROFILER_CODE_OBJECT_LOAD)
provides a unique identifier for a bundle of one or more GPU kernel symbols that are loaded
for a specific GPU agent. For example, if your application leverages a multi-GPU system
consisting of four Vega20 GPUs and four MI100 GPUs, at least eight code objects will be loaded: one code
object for each GPU. Each code object will be associated with a set of kernel symbols.
The rocprofiler_callback_tracing_code_object_kernel_symbol_register_data_t payload
(kind=ROCPROFILER_CALLBACK_TRACING_CODE_OBJECT, operation=ROCPROFILER_CODE_OBJECT_DEVICE_KERNEL_SYMBOL_REGISTER)
provides a globally unique identifier for the specific kernel symbol along with the kernel name and
several other static properties of the kernel such as scratch size, scalar general purpose register count, and so on.
Note
The kernel identifiers for two identical kernel symbols with the same properties (kernel name, scratch size, and so on) that are part of similar code objects loaded for different GPU agents will still be unique. Furthermore, the identifier for a code object and its kernel symbols after being unloaded and then reloaded, will also be unique.
Here is the general sequence of events when a code object is loaded and unloaded:
Callback: load code object
kind=
ROCPROFILER_CALLBACK_TRACING_CODE_OBJECToperation=
ROCPROFILER_CODE_OBJECT_LOADphase=
ROCPROFILER_CALLBACK_PHASE_LOAD
Callback: load kernel symbol
kind=
ROCPROFILER_CALLBACK_TRACING_CODE_OBJECToperation=
ROCPROFILER_CODE_OBJECT_DEVICE_KERNEL_SYMBOL_REGISTERphase=
ROCPROFILER_CALLBACK_PHASE_LOADRepeats for each kernel symbol in code object
Execute application
Callback: unload kernel symbol
kind=
ROCPROFILER_CALLBACK_TRACING_CODE_OBJECToperation=
ROCPROFILER_CODE_OBJECT_DEVICE_KERNEL_SYMBOL_REGISTERphase=
ROCPROFILER_CALLBACK_PHASE_UNLOADRepeats for each kernel symbol in code object
Callback: unload code object
kind=
ROCPROFILER_CALLBACK_TRACING_CODE_OBJECToperation=
ROCPROFILER_CODE_OBJECT_LOADphase=
ROCPROFILER_CALLBACK_PHASE_UNLOAD
Note
ROCprofiler-SDK doesn’t provide an interface to query information outside of the
code object tracing service. If you wish to associate kernel names with kernel tracing records,
the tool must be configured to create a copy of the relevant information when the code objects and
kernel symbol are loaded. However, any constant string fields like const char* kernel_name
don’t need to be copied as these are guaranteed to be valid pointers until after ROCprofiler-SDK finalization.
If a tool decides to delete its copy of the data associated with a code object or kernel symbol
identifier when the code object and kernel symbols are unloaded, it is highly recommended to flush
all buffers that might contain references to that code object or kernel symbol identifier before
deleting the associated data.
For a sample of code object tracing, see samples/code_object_tracing.