Why there is a difference between the values shown in top and jtop?

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Orin
1

Why are the values shown in top and jtop different? Which one is more accurate? As shown in the screenshots: in Figure 1, top indicates that PID 3285 is using 6.2 GB of RES memory, whereas in Figure 2, jtop shows that the same PID 3285 is only using 1.6 GB of MEM. Which one is correct?

Additionally, I noticed a [GPU MEM] field, but there’s also another MEM field, which leaves me confused about their exact meanings. Could someone help clarify this? Or is there any documentation explaining the significance of these fields? I’ve already checked jetson-stats 4.3.0, but it doesn’t seem to provide any information about the meaning of the fields.

Figure 1
top

Figure 2
jtop

4

Hi,
top command is default in Linux system and jtop is GUI of sudo tegrastats. There are some unique device nodes on Jetson which provide the information. Detail of tegrastats is described in

Tegrastats Utility — NVIDIA Jetson Linux Developer Guide 1 documentation

5

Hi @DaneLLL
I’ve also reviewed this document, but it doesn’t seem to provide any information about the difference between GPU MEM and MEM, or the definitions of these fields. For example, what exactly does the value of GPU MEM represent?

6

Hi,

Please find the document here:

Memory occupied

Extract resident set size (VmRSS) (Second field) in /proc/[PID]/statm:

VmRSS is the resident set size of the process, which is the portion of the process’s memory that is held in RAM and is not swapped out to disk. This is the amount of memory that the process is currently using.

GPU Memory occupied

This value is the GPU memory occupied from the process.

Thanks.

7

@AastaLLL
Based on the information you provided, in Figure 1, that process PID 63999 is using 444 MB, while the GPU memory usage is 5.9 GB? If so, does this mean that PID 63999 is using a total of 5.9 GB + 444 MB of memory?

Figure 1
image

8

Hi @kerokerokero

Thank you for your detailed post.

jtop read the status from all processes that are working with the jetson GPU from /debug/nvmap/iovmm/maps from this table extract from /proc/[PID]/statm

The MEM is the only memory used from the process (not for the GPU), and GPU MEM is the shared memory used by the GPU.

Let me know fi I helped you.

Best,
Raffaello

9

Hi @Raffaello

Based on the information in the image I provided, could you please clarify how much resource PID 63999 requires to run? Is it 5.9GB + 444MB, 444MB, or 5.9GB?