The memory usage displayed by nvtop is different from that of nvidia-smi

[Kelvinlby]

I noticed that on my platform (Ubuntu 24.04, RTX3060), when it comes to VRAM utilization, nvtop gives a different number to nvidia-smi

[Kelvinlby]

I noticed this when I was writing a C program which needs to get VRAM usage of Nvidia GPUs. I used the following code and get the same result as what nvidia-smi shows. However, I'm not sure whether it takes all VRAM utilization into account and which program (nvtop/nvidia-smi) shows the real utilization.

By the way, in most cases nvtop shows larger VRAM utilization than nvidia-smi.

UINT32 nvidiaUsedVram(void) {
    size_t freeMemory, totalMemory;
    cudaMemGetInfo(&freeMemory, &totalMemory);
    return (totalMemory - freeMemory) / (1024 * 1024);
}

[canytam-krystal]

I face the same problem. After my os upgraded to 24.04, the dispaly of nvtop is no longer correct even I update the nvtop to 3.0.2-1.

[Syllo]

Hard to say which one is closer to what we can expect as "allocated memory". Nvtop uses the result of nvmlDeviceGetMemoryInfo_v2 coming directly from the driver!

The value nvtop displays is the used memory: Allocated device memory (in bytes).
Perhaps nvidia-smi subtracts the reserved memory? I'm not sure.

[Kelvinlby]

Hard to say which one is closer to what we can expect as "allocated memory". Nvtop uses the result of nvmlDeviceGetMemoryInfo_v2 coming directly from the driver!

The value nvtop displays is the used memory: Allocated device memory (in bytes). Perhaps nvidia-smi subtracts the reserved memory? I'm not sure.

Not sure either, since both methods are offered by nvidia.