showmem

Display memory information

Syntax:

showmem [-D type] [-d file] [-P [pid]] [-S] [-v[v]...]

Runs on:

QNX Neutrino

Options:

-D type

Show detailed process information. The type is one or more of the following letters:

• h — heap
• l — libraries; the contribution from the shared objects
• m — memory mappings
• s — stack; the contribution from the threads

-d file

Dump the raw mapinfo into the specified file.

-P [pid]

Show a summary of the memory usage for the processes and the shared libraries in the system. If you specify pid, showmem displays information only for the process with that ID.

-S

Show a summary of the free and used memory for the entire system.

-v[v]...

Increase the verbosity of the output.

You must specify at least one of these options.

Description:

The showmem utility displays memory information to help you determine how your system is using memory.

-S option

If you specify the -S option, the output includes a summary for the whole system. For example:

System RAM:      511M (     536394752) 
Total Used:      381M (     399794216) 
 Used Private:   378M (     396812328) 
 Used Shared:   2912K (       2981888) 

The fields are as follows:

• System RAM: total RAM of the system
• Total used: the sum of the Used Private and Used Shared
• Used Private: private blocks, plus shared objects that are referenced by only one process
• Used Shared: shared blocks that are referenced by more than one process

-P option

Use the -P option to display a summary of memory usage by the processes and shared libraries in the system. If you specify a pid, showmem displays the memory information of the specified process; if you don't, showmem displays the memory summary of all processes and shared objects.

The report is broken down into these sections:

Process

The Process section shows the memory that the process claims it's consuming. The fields are:

• Total: sum of Code + Data + Heap + Stack + Other
• Code: the code/text section of the process + the code/text section of the shared libraries being used only by that process
• Data: the data/bss section of the process + the data/bss section of the shared libraries referenced by that process
• Heap: the heap of the process
• Stack: the stack of the process
• Other: other memory not falling into the types above, mainly shared memories referenced by the process
• process ID
• the name of the process

Let's take the process devc-con-hid as an example:

Process listing (Total, Code, Data, Heap, Stack, Other)
   ...
   819200     602112      24576     167936      24576          0        4103 devc-con-hid
  

Total = 602112 + 24576 + 167936 + 24576 + 0 = 819200.

Shared

The Shared section shows all of the objects that have been identified as being shared by more than one process mapping. The fields are:

• Total: sum of Code + Data + Heap + Stack + Other
• Code: the code/text section of the shared library
• Data: 0
• Heap: 0
• Stack: 0
• Other: other memory not falling into the types above, mainly shared memory objects
• pid: -1
• name of the shared object

For example, libc.so.3 is referenced by almost all the processes. Therefore, it's shown in the Shared section; the information for it could be like this:

Shared shared objects (Total, Code, Data, Heap, Stack, Other)
   ...
   499712     499712          0          0          0          0          -1 proc/boot/libc.so.3
  

Here's another example of an entry for shared memory in the Shared section:

Shared shared objects (Total, Code, Data, Heap, Stack, Other)
     ...
     4096          0          0          0          0       4096          -1 /dev/shmem/ctl-1002,5964,0
  

-D option

If you specify the -D option, showmem shows detailed process information. The Process section shows the breakdown of the code, data, stack, heap, and libraries being used by the processes. The Shared section is just the same as the Shared section shown with the -P option.

---

If a value is shown in parentheses, this memory has already been accounted for the total memory information. This memory mapping might originate from within another, not allocated from system RAM.

---

For example, if you specify -Dsl, the information for devc-con-hid might look like this:

Process listing (Total, Code, Data, Heap, Stack, Other)
   ...
   319488     102400      24576     167936      24576          0        4103 devc-con-hid
        0          0          0          0       4096          0        4103 devc-con-hid (thread 2)
        0          0          0          0      20480          0        4103 devc-con-hid (thread 1)
        0     102400       8192          0          0          0        4103 devc-con-hid (proc/boot/devc-con-hid)
        0          0      16384          0          0          0        4103 devc-con-hid (proc/boot/libc.so.3)
        0          0          0          0          0  (   36864)       4103 devc-con-hid (/dev/mem)

From the breakdown details, we can see:

• This process has two threads. The stack size of thread 2 is 4096 bytes (4 KB), and the stack size of thread 1 is 20480 bytes (20 KB).
• The private data of the shared library libc.so.3 contributes 16384 bytes to the total memory usage of the process.
• This process refers to the memory /dev/mem, but this memory has already been accounted for in the total memory usage. Therefore, we don't include this size in the total memory usage of this process.

See also:

pidin, ps

Fine-Tuning Your System in the Neutrino User's Guide