Is this normal? Running latest NR Network Explorer on Ubuntu 9.04

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2435 root 20 0 120m 4496 3168 S 0 0.9 0:09.70 nrservice

Kind Regards
/Bernt

It depends. The virtual memory would be normal, it would be better to provide vmstat values. The more important factor needs to monitor is Page-outs. It would be better to use vmstat to monitor your system and pay more attention to the "free", "si" and "so" values.

The free column shows the amount of free memory, si shows page-ins and so shows page-outs. In this example, the so column is zero consistently, indicating there are no page-outs.

BTW, there is something interesting on Linux, in terms of this case.

1. Linux uses a technique called "demand paging" where the virtual memory of a process is brought into physical memory only when a process attempts to use it. And it counts everyting, code, data and shared libs, in the virtual address space.

2. When the kernel detects that memory is running low, it attempts to free up memory by paging out. Though this may happen briefly from time to time, if page-outs are plentiful and constant, the kernel can reach a point where it's actually spending more time managing paging activity than running the applications, and system performance suffers. This woeful state is referred to as thrashing.

Correct me if I was wrong.

Thanks,
KevinZ - NeoRouter team

Thanks for the reply.

After a few hours it looks like this.

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
4267 root 20 0 448m 3132 1288 S 0 0.6 5:18.62 nrservice

The Swap is now using 35108k. It use to be 0k.

/Bernt

It's normal and you don't need to care about the VIRT, but the RES.
The RES indicates the real physical memory used by an application, VIRT does not use your physical memory and will not effects other applications.

You can use top to keep monitoring the physical memory usage.
From the information you provided, the RES was 4496KB and later is 3132KB. It's normal.

If you really want to know what's counted in the VIRT, you can use:
pmap or cat /proc/PID/maps to find out.

BTW, there are some books discussing the virtual memory management on Linux. Hope it helps.

Thanks,
KevinZ - NeoRouter team

Ok, sounds good. Thanks.