Svmon - IBM pSeries Tuning Manual

3.3.1 svmon

The svmon command provides information about the virtual memory usage by the kernel and
user processes in the system at any given time. For example, to see system-wide information
about the segments (256MB chunk of virtual memory), type the following command as root:
svmon -S
The command prints out segment information sorted according to values in the Inuse field, which
shows the number of virtual pages in the segment that are mapped into the process address space.
Segments of type work with a blank description field belong to user processes. If the LPage is
set to Y, the segment contains large pages. These segments always have 65536 in the Inuse,
Pin, and Virtual fields because this is the number of 4KB pages in the 256MB segment. In other
words, large pages are mapped into the process address space with a granularity of 256MB even
if a process is using a small fraction of it. A segment can have either large pages or small pages,
but not both.
Vsid Esid Type
101810 - work
161836 - work
1e09de - work kernel heap
9e0 - work kernel heap
190899 - work mbuf pool
20002 - work page table area
0 - work kernel segment
70b07 - work other kernel segments
c0b0c - work other kernel segments
1b00bb - work vmm software hat
a09aa - work loader segment
Memory overhead associated with HPS communication buffers allocated in support of MPI
processes and IP is shown in the map as other kernel segments. Unlike user segments
with large pages, these segments have just one large page or 4096 4KB pages. The segment
named mbuf pool indicates a system-wide pool of pinned memory allocated for mbufs mostly
used in support of IP. The Pin field shows the number of pinned 4KB pages in a segment (for
example, pages that cannot be paged out). Large pages are always pinned.
To see a segment allocation map organized by process, type the following command as root:
svmon -P
The output is sorted according to the aggregate Inuse value for each process. This is useful in
finding virtual memory demands for all processes on the node. The virtual segment ID (Vsid) is a
unique segment ID that is listed in more than one process when processes share data (for
example, if multiple MPI tasks use shared memory or program text).
Pid Command
381118 sppm
pshpstuningguidewp040105.doc
Description
Inuse Pin Pgsp Virtual 64-bit Mthrd LPage
448221 3687 2675 449797
LPage Inuse Pin
Y 65536 65536
Y 65536 65536
- 30392 92
- 26628 20173
- 15793 15793
- 7858 168 7690
- 6394 3327 953
Y 4096 4096
Y 4096 4096
- 4096 4096
- 3074 0
Y Y
Pgsp Virtual
0 65536
0 65536
0 30392
0 26628
0 15793
7858
6394
0 4096
0 4096
0 4096
0 3074
N
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