GPU Variable and Data Display

Totalview® for HPC User Guide : PART V Using the CUDA Debugger : Chapter 26 CUDA Debugging Tutorial : Displaying CUDA Program Elements : GPU Variable and Data Display

TotalView can display variables and data from a CUDA thread. The stack frame pane of the process window contains parameter, register, local, and shared variables, as shown in Figure 264. The variables are contained within the lexical blocks in which they are defined. The type of the variable determines its storage kind (register, or local, shared, constant or global memory). The address is a PTX register name or an offset within the storage kind.

Figure 264 – A variable window displaying a parameter

Dive on a variable in the stack frame pane or source pane in the process window to open a variable window. Figure 264 shows a parameter named A with type @parameter const Matrix.

The identifier @parameter is a TotalView built-in type storage qualifier that tells the debugger the storage kind of "A" is parameter storage. The debugger uses the storage qualifier to determine how to locate A in device memory. The supported type storage qualifiers are shown in Table 2.

Table 2: Supported Type Storage Qualifiers
Storage Qualifier	Meaning
@parameter	Address is an offset within parameter storage.
@local	Address is an offset within local storage.
@shared	Address is an offset within shared storage.
@constant	Address is an offset within constant storage.
@global	Address is an offset within global storage.
@register	Address is a PTX register name (see below).

The type storage qualifier is a necessary part of the type for correct addressing in the debugger. When you edit a type or a type cast, make sure that you specify the correct type storage qualifier for the address offset.