Question

In top, I noticed that my c program (using CUDA 3.2) has a virtual size of 28g or more (looking at VIRT), on every run right from the beginning. This doesn’t make ANY sense to me. The resident memory makes sense and is only around 2g on my largest data set. I know at some point in the past the virtual size was not so large, but I’m not sure when the change occurred.

Why would my process use 28g of virtual memory (or why would top’s VIRT be so large)? I understand that VIRT includes the executable binary (only 437K), shared libraries, and “data area”. What is the “data area”? How can I find out how much memory the shared libraries require? What about other elements of my process’s total memory?

contents of /proc/< pid >/smaps (1022 lines) here: http://pastebin.com/fTJJneXr

One of the entries from smaps show that one of them accounts for MOST of it, but has no label… how can I find out what this “blank” entry is that has 28gb?

200000000-900000000 ---p 00000000 00:00 0 
Size:           29360128 kB
Rss:                   0 kB
Pss:                   0 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:         0 kB
Referenced:            0 kB
Anonymous:             0 kB
Swap:                  0 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Locked:                0 kB

—

ubuntu 11.04 64-bit
16 GB RAM

Answer 1

UVA requires CUDA to allocate enough virtual memory to map all of both GPU and system memory. Please see post #5 in the following thread on the NVIDIA forums: