I'm running Opensuse 11.0 KDE 4.3 RC3 on my Thinkpad R61i w/ Intel 945GM card. I like to keep a strict check on memory usage as I use several GUI development tools and hardware drivers that use a good amount of memory. I have 1 GB of RAM on my laptop.

I noticed a discrepancy between the memory usage reported by Htop and System Monitor. Particularly for individual apps, like FF3.5 & Amarok...htop reports a higher memory usage than System Monitor. I've attached a screenshot of htop and SM.



The first 2 lines in the htop console in the RES section is what I go by for physical RAM usage. It indicates a usage of 103M for Amarok, SM reports around 60MB. FF3.5 on htop is 85MB and SM is 62.5. Can someone help on why this major discrepancy...or is there something in the way htop and SM collect and report memory? The interesting part is that both indicate the same overall RAM usage.

Thanks,
Anshul

The problem is that measuring an application's memory usage is difficult in Linux due to the fact that a lot of memory is shared between various applications, and there is no "right" way to attribute how much of this shared memory belongs to which application.

For more info, see here's a nice article:
http://virtualthreads.blogspot.com/2006/02/understanding-memory-usage-on-linux.html