Physical Memory != Memory from Top

Ian_7 — Fri, 08 Dec 2000 16:18:40 GMT

I have been hunting in the forums for an answer to this question but haven't been able to turn anything up.

We are running HP-UX e-com B.11.00 A 9000/898 1608673371 two-user license and at boot time the system reports that it has Physical memory of 2621440 Kb, Lockable 2234656 Kb, and Avail of 2304564 Kb. That's all fine and good but when I run top I don't seem to be 'seeing' all of the memory. Is there some way of disabling memory on a system? I don't have the STM stuff installed yet but if I need to I will. Are the specific commands that would tell me if I am using all the memory that the kernel detected at boot?

thanks!
ian

Re: Physical Memory != Memory from Top

Alex Glennie — Fri, 08 Dec 2000 16:28:36 GMT

Please explain the memory values reported by top(1).

Configuration Info

Solution

top() calls pstat() to get its memory information. The
values it retrieves/displays are:

psd_rm Total physical memory pages in the system
dedicated to text, data, or stack segments
for all processes on the system.

psd_arm Total physical memory pages for runnable
processes, as opposed to sleeping processes.

psd_vm Total memory pages dedicated to text, data,
or stack segments for all processes on the
system. Some of these pages are paged out
to disk.

psd_avm Total memory pages for runnable processes,
as opposed to sleeping or stopped processes.

psd_free Physical pages the system considers to
be unused and available to processes.

These values map to the top() output as follows:

Memory: 2676K (1492K) real, 3536K (1276K) virtual, 2244K free
psd_rm (psd_arm) psd_vm (psd_avm) psd_free

The confusion comes in that top is not reporting anything
about what you have available, but rather what is being used.
For example, in the line above, 2676K real does not mean there is
2676Kbytes of total physical memory but that this amount has been
used for process memory structures.

Here is an example memory line from top output:

| Memory: 2080K (1672K) real, 5564K (3044K) virtual, 696K free
| ^ ^ ^ ^ ^
| | | | | |
| 1 2 3 4 5

The entries are described below:

1. Total physical memory in the system dedicated to text, data or
stack segments for all processes on the system.

2. Total physical memory for runnable processes, as opposed to
sleeping processes.

3. Total memory dedicated to text, data or stack segments for all processes
on the system. Some of this is paged out to disk (that is, not all
of this is in current physical memory.

4. Total memory for runnable processes, as opposed to sleeping or stopped
processes.

5. Physical memory the system considers to be unused and available to new
processes. When this value is low, swapping is likely to occur.

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Physical Memory != Memory from Top

Re: Physical Memory != Memory from Top