Multi-Target

Debugging with Intel® Distribution for GDB* on Linux* OS Host

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ID 766459

Date 3/22/2024

Version

Public

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Multi-Target

The multi-target feature enables debugging of multiple targets in a single debugging session.

NOTE:

This section assumes you are debugging on a GPU.

With this feature, you can define breakpoints inside and outside the kernel to debug the host portion of the program. For example, define two breakpoints and run the target as follows:


$ export ONEAPI_DEVICE_SELECTOR=level_zero:gpu
$ export ZET_ENABLE_PROGRAM_DEBUGGING=1
$ gdb-oneapi array-transform

(gdb) break 54

Breakpoint 1 at 0x405800: file /path/to/array-transform.cpp, line 54.

(gdb) break 81

Breakpoint 2 at 0x403e13: file /path/to/array-transform.cpp, line 81.

(gdb) run gpu

[...]
[Switching to Thread 1.129 lane 1]

Thread 2.129 hit Breakpoint 1, with SIMD lanes [0-7], main::{lambda(auto:1&)#1}::operator()[...] at array-transform.cpp:54
54          int element = in[index];  // breakpoint-here

Now you are inside the kernel (in this case, the kernel is running on the GPU). The context is Thread 2.129, lane 0.

Disable the breakpoint at line 54 and continue:


disable 1

continue

Continuing.
[Switching to Thread 0x7ffff7fd9780 (LWP 19604)]


Thread 1.1 "array-transform" hit Breakpoint 2, main (...)
  at /path/to/array-transform.cpp:81
81    cout << "success; result is correct.\n";

Try executing print input and print output as follows:


(gdb) print input[6]

$1 = 106

(gdb) print output[6]

$2 = 206

This time the stop event is received from the host. The context is automatically switched to Thread 1.1. You can investigate the host-side values as shown above.

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Debugging with Intel® Distribution for GDB* on Linux* OS Host

Multi-Target