Debugging with HIP#
AMD debugging tools include ltrace and ROCgdb. External tools are available and can be found online. For example, if you’re using Windows, you can use Microsoft Visual Studio and WinGDB.
You can trace and debug your code using the following tools and techniques.
Tracing#
You can use tracing to quickly observe the flow of an application before reviewing the detailed information provided by a command-line debugger. Tracing can be used to identify issues ranging from accidental API calls to calls made on a critical path.
ltrace is a standard Linux tool that provides a message to stderr
on every dynamic library call. You
can use ltrace to visualize the runtime behavior of the entire ROCm software stack.
Here’s a simple command-line example that uses ltrace to trace HIP APIs and output:
$ ltrace -C -e "hip*" ./hipGetChanDesc
hipGetChanDesc->hipCreateChannelDesc(0x7ffdc4b66860, 32, 0, 0) = 0x7ffdc4b66860
hipGetChanDesc->hipMallocArray(0x7ffdc4b66840, 0x7ffdc4b66860, 8, 8) = 0
hipGetChanDesc->hipGetChannelDesc(0x7ffdc4b66848, 0xa63990, 5, 1) = 0
hipGetChanDesc->hipFreeArray(0xa63990, 0, 0x7f8c7fe13778, 0x7ffdc4b66848) = 0
PASSED!
+++ exited (status 0) +++
Here’s another example that uses ltrace to trace hsa APIs and output:
$ ltrace -C -e "hsa*" ./hipGetChanDesc
libamdhip64.so.4->hsa_init(0, 0x7fff325a69d0, 0x9c80e0, 0 <unfinished ...>
libhsa-runtime64.so.1->hsaKmtOpenKFD(0x7fff325a6590, 0x9c38c0, 0, 1) = 0
libhsa-runtime64.so.1->hsaKmtGetVersion(0x7fff325a6608, 0, 0, 0) = 0
libhsa-runtime64.so.1->hsaKmtReleaseSystemProperties(3, 0x80084b01, 0, 0) = 0
libhsa-runtime64.so.1->hsaKmtAcquireSystemProperties(0x7fff325a6610, 0, 0, 1) = 0
libhsa-runtime64.so.1->hsaKmtGetNodeProperties(0, 0x7fff325a66a0, 0, 0) = 0
libhsa-runtime64.so.1->hsaKmtGetNodeMemoryProperties(0, 1, 0x9c42b0, 0x936012) = 0
...
<... hsaKmtCreateEvent resumed> ) = 0
libhsa-runtime64.so.1->hsaKmtAllocMemory(0, 4096, 64, 0x7fff325a6690) = 0
libhsa-runtime64.so.1->hsaKmtMapMemoryToGPUNodes(0x7f1202749000, 4096, 0x7fff325a6690, 0) = 0
libhsa-runtime64.so.1->hsaKmtCreateEvent(0x7fff325a6700, 0, 0, 0x7fff325a66f0) = 0
libhsa-runtime64.so.1->hsaKmtAllocMemory(1, 0x100000000, 576, 0x7fff325a67d8) = 0
libhsa-runtime64.so.1->hsaKmtAllocMemory(0, 8192, 64, 0x7fff325a6790) = 0
libhsa-runtime64.so.1->hsaKmtMapMemoryToGPUNodes(0x7f120273c000, 8192, 0x7fff325a6790, 0) = 0
libhsa-runtime64.so.1->hsaKmtAllocMemory(0, 4096, 4160, 0x7fff325a6450) = 0
libhsa-runtime64.so.1->hsaKmtMapMemoryToGPUNodes(0x7f120273a000, 4096, 0x7fff325a6450, 0) = 0
libhsa-runtime64.so.1->hsaKmtSetTrapHandler(1, 0x7f120273a000, 4096, 0x7f120273c000) = 0
<... hsa_init resumed> ) = 0
libamdhip64.so.4->hsa_system_get_major_extension_table(513, 1, 24, 0x7f1202597930) = 0
libamdhip64.so.4->hsa_iterate_agents(0x7f120171f050, 0, 0x7fff325a67f8, 0 <unfinished ...>
libamdhip64.so.4->hsa_agent_get_info(0x94f110, 17, 0x7fff325a67e8, 0) = 0
libamdhip64.so.4->hsa_amd_agent_iterate_memory_pools(0x94f110, 0x7f1201722816, 0x7fff325a67f0, 0x7f1201722816 <unfinished ...>
libamdhip64.so.4->hsa_amd_memory_pool_get_info(0x9c7fb0, 0, 0x7fff325a6744, 0x7fff325a67f0) = 0
libamdhip64.so.4->hsa_amd_memory_pool_get_info(0x9c7fb0, 1, 0x7fff325a6748, 0x7f1200d82df4) = 0
...
<... hsa_amd_agent_iterate_memory_pools resumed> ) = 0
libamdhip64.so.4->hsa_agent_get_info(0x9dbf30, 17, 0x7fff325a67e8, 0) = 0
<... hsa_iterate_agents resumed> ) = 0
libamdhip64.so.4->hsa_agent_get_info(0x9dbf30, 0, 0x7fff325a6850, 3) = 0
libamdhip64.so.4->hsa_agent_get_info(0x9dbf30, 0xa000, 0x9e7cd8, 0) = 0
libamdhip64.so.4->hsa_agent_iterate_isas(0x9dbf30, 0x7f1201720411, 0x7fff325a6760, 0x7f1201720411) = 0
libamdhip64.so.4->hsa_isa_get_info_alt(0x94e7c8, 0, 0x7fff325a6728, 1) = 0
libamdhip64.so.4->hsa_isa_get_info_alt(0x94e7c8, 1, 0x9e7f90, 0) = 0
libamdhip64.so.4->hsa_agent_get_info(0x9dbf30, 4, 0x9e7ce8, 0) = 0
...
<... hsa_amd_memory_pool_allocate resumed> ) = 0
libamdhip64.so.4->hsa_ext_image_create(0x9dbf30, 0xa1c4c8, 0x7f10f2800000, 3 <unfinished ...>
libhsa-runtime64.so.1->hsaKmtAllocMemory(0, 4096, 64, 0x7fff325a6740) = 0
libhsa-runtime64.so.1->hsaKmtQueryPointerInfo(0x7f1202736000, 0x7fff325a65e0, 0, 0) = 0
libhsa-runtime64.so.1->hsaKmtMapMemoryToGPUNodes(0x7f1202736000, 4096, 0x7fff325a66e8, 0) = 0
<... hsa_ext_image_create resumed> ) = 0
libamdhip64.so.4->hsa_ext_image_destroy(0x9dbf30, 0x7f1202736000, 0x9dbf30, 0 <unfinished ...>
libhsa-runtime64.so.1->hsaKmtUnmapMemoryToGPU(0x7f1202736000, 0x7f1202736000, 4096, 0x9c8050) = 0
libhsa-runtime64.so.1->hsaKmtFreeMemory(0x7f1202736000, 4096, 0, 0) = 0
<... hsa_ext_image_destroy resumed> ) = 0
libamdhip64.so.4->hsa_amd_memory_pool_free(0x7f10f2800000, 0x7f10f2800000, 256, 0x9e76f0) = 0
PASSED!
Debugging#
You can use ROCgdb for debugging and profiling.
ROCgdb is the ROCm source-level debugger for Linux and is based on GNU Project debugger (GDB). the GNU source-level debugger, equivalent of CUDA-GDB, can be used with debugger frontends, such as Eclipse, Visual Studio Code, or GDB dashboard. For details, see (ROCm/ROCgdb).
Below is a sample how to use ROCgdb run and debug HIP application, ROCgdb is installed with ROCM package in the folder /opt/rocm/bin.
$ export PATH=$PATH:/opt/rocm/bin
$ rocgdb ./hipTexObjPitch
GNU gdb (rocm-dkms-no-npi-hipclang-6549) 10.1
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
...
For bug reporting instructions, please see:
<https://github.com/ROCm/ROCgdb/issues>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
...
Reading symbols from ./hipTexObjPitch...
(gdb) break main
Breakpoint 1 at 0x4013d1: file /home/test/hip/tests/src/texture/hipTexObjPitch.cpp, line 98.
(gdb) run
Starting program: /home/test/hip/build/directed_tests/texture/hipTexObjPitch
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, main ()
at /home/test/hip/tests/src/texture/hipTexObjPitch.cpp:98
98 texture2Dtest<float>();
(gdb)c
Debugging HIP applications#
The following Linux example shows how to get useful information from the debugger while running a simple memory copy test, which caused a segmentation fault issue.
test: simpleTest2<?> numElements=4194304 sizeElements=4194304 bytes
Segmentation fault (core dumped)
(gdb) run
Starting program: /home/test/hipamd/build/directed_tests/runtimeApi/memory/hipMemcpy_simple
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Breakpoint 1, main (argc=1, argv=0x7fffffffdea8)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:147
147 int main(int argc, char* argv[]) {
(gdb) c
Continuing.
[New Thread 0x7ffff64c4700 (LWP 146066)]
Thread 1 "hipMemcpy_simpl" received signal SIGSEGV, Segmentation fault.
0x000000000020f78e in simpleTest2<float> (numElements=4194304, usePinnedHost=true)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:104
104 A_h1[i] = 3.14f + 1000 * i;
(gdb) bt
#0 0x000000000020f78e in simpleTest2<float> (numElements=4194304, usePinnedHost=true)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:104
#1 0x000000000020e96c in main (argc=<optimized out>, argv=<optimized out>)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:163
(gdb) info thread
Id Target Id Frame
* 1 Thread 0x7ffff64c5880 (LWP 146060) "hipMemcpy_simpl" 0x000000000020f78e in simpleTest2<float> (numElements=4194304, usePinnedHost=true)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:104
2 Thread 0x7ffff64c4700 (LWP 146066) "hipMemcpy_simpl" 0x00007ffff6b0850b in ioctl
() from /lib/x86_64-linux-gnu/libc.so.6
(gdb) thread 2
[Switching to thread 2 (Thread 0x7ffff64c4700 (LWP 146066))]
#0 0x00007ffff6b0850b in ioctl () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0 0x00007ffff6b0850b in ioctl () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007ffff6604568 in ?? () from /opt/rocm/lib/libhsa-runtime64.so.1
#2 0x00007ffff65fe73a in ?? () from /opt/rocm/lib/libhsa-runtime64.so.1
#3 0x00007ffff659e4d6 in ?? () from /opt/rocm/lib/libhsa-runtime64.so.1
#4 0x00007ffff65807de in ?? () from /opt/rocm/lib/libhsa-runtime64.so.1
#5 0x00007ffff65932a2 in ?? () from /opt/rocm/lib/libhsa-runtime64.so.1
#6 0x00007ffff654f547 in ?? () from /opt/rocm/lib/libhsa-runtime64.so.1
#7 0x00007ffff7f76609 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#8 0x00007ffff6b13293 in clone () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) thread 1
[Switching to thread 1 (Thread 0x7ffff64c5880 (LWP 146060))]
#0 0x000000000020f78e in simpleTest2<float> (numElements=4194304, usePinnedHost=true)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:104
104 A_h1[i] = 3.14f + 1000 * i;
(gdb) bt
#0 0x000000000020f78e in simpleTest2<float> (numElements=4194304, usePinnedHost=true)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:104
#1 0x000000000020e96c in main (argc=<optimized out>, argv=<optimized out>)
at /home/test/hip/tests/src/runtimeApi/memory/hipMemcpy_simple.cpp:163
(gdb)
...
Debugging HIP applications using Windows tools can be more informative than on Linux. Windows tools provides more visibility into debug codes, which makes it easier to inspect variables, watch multiple details, and examine call stacks.
Useful environment variables#
HIP provides environment variables that allow HIP, hip-clang, or HSA drivers to prevent certain features and optimizations. These are not intended for production, but can be useful to diagnose synchronization problems in the application (or driver).
Some of the more widely used environment variables are described in this section. These are supported on the Linux ROCm path and Windows.
Kernel enqueue serialization#
You can control kernel command serialization from the host:
AMD_SERIALIZE_KERNEL
, for serializing kernel enqueueAMD_SERIALIZE_KERNEL = 1
, Wait for completion before enqueueAMD_SERIALIZE_KERNEL = 2
, Wait for completion after enqueueAMD_SERIALIZE_KERNEL = 3
, Both
Or
AMD_SERIALIZE_COPY
, for serializing copiesAMD_SERIALIZE_COPY = 1
, Wait for completion before enqueueAMD_SERIALIZE_COPY = 2
, Wait for completion after enqueueAMD_SERIALIZE_COPY = 3
, Both
So HIP runtime can wait for GPU idle before/after any GPU command depending on the environment setting.
Making device visible#
For systems with multiple devices, you can choose to make only certain device(s) visible to HIP using
HIP_VISIBLE_DEVICES
(or CUDA_VISIBLE_DEVICES
on an NVIDIA platform). Once enabled, HIP can
only view devices that have indices present in the sequence. For example:
$ HIP_VISIBLE_DEVICES=0,1
Or in the application:
if (totalDeviceNum > 2) {
setenv("HIP_VISIBLE_DEVICES", "0,1,2", 1);
assert(getDeviceNumber(false) == 3);
... ...
}
Dump code object#
To analyze compiler-related issues, you can use the dump code object:
GPU_DUMP_CODE_OBJECT
.
HIP environment variable summary#
Here are some of the more commonly used environment variables:
Environment variable |
Default value |
Usage |
AMD_LOG_LEVEL
|
0 |
0: Disable log.
|
AMD_LOG_MASK
|
0x7FFFFFFF |
0x1: Log API calls
|
HIP_LAUNCH_BLOCKING
|
0 |
0: Disable. Kernel executes normally.
|
HIP_VISIBLE_DEVICES (or CUDA_VISIBLE_DEVICES)
|
0,1,2: Depending on the number of devices on the system |
|
GPU_DUMP_CODE_OBJECT
|
0 |
0: Disable
|
AMD_SERIALIZE_KERNEL
|
0 |
1: Wait for completion before enqueue
|
AMD_SERIALIZE_COPY
|
0 |
1: Wait for completion before enqueue
|
HIP_HOST_COHERENT
|
0 |
0: memory is not coherent between host and GPU
|
AMD_DIRECT_DISPATCH
|
1 |
0: Disable
|
GPU_MAX_HW_QUEUES
|
4 |
The variable controls how many independent hardware queues HIP runtime can create per process, per device. If an application allocates more HIP streams than this number, then HIP runtime reuses the same hardware queues for the new streams in a round-robin manner. Note that this maximum number does not apply to hardware queues that are created for CU-masked HIP streams, or cooperative queues for HIP Cooperative Groups (single queue per device). |
General debugging tips#
gdb --args
can be used to pass the executable and arguments togdb
.You can set environment variables (
set env
) from within GDB on Linux:(gdb) set env AMD_SERIALIZE_KERNEL 3
Note
This
gdb
command does not use an equal (=) sign.The GDB backtrace shows a path in the runtime. This is because a fault is caught by the runtime, but it is generated by an asynchronous command running on the GPU.
To determine the true location of a fault, you can force the kernels to run synchronously by setting the environment variables
AMD_SERIALIZE_KERNEL=3
andAMD_SERIALIZE_COPY=3
. This forces HIP runtime to wait for the kernel to finish running before returning. If the fault occurs when a kernel is running, you can see the code that launched the kernel inside the backtrace. The thread that’s causing the issue is typically the one insidelibhsa-runtime64.so
.VM faults inside kernels can be caused by:
Incorrect code (e.g., a for loop that extends past array boundaries)
Memory issues, such as invalid kernel arguments (null pointers, unregistered host pointers, bad pointers)
Synchronization issues
Compiler issues (incorrect code generation from the compiler)
Runtime issues