HP-UX 11i v3 Memory Management Subsystem

9
The example for swapping and switching activity was obtained by invoking the command as sar -w 60 1:
# sar -w 60 1
HP-UX vmkona1 B.11.31 U ia64 01/06/10
10:51:29 swpin/s bswin/s swpot/s bswot/s pswch/s
10:52:29 0.00 0.0 0.00 0.0 37547
In this example, the 0.0 in the bswin/s column indicates that there are no 512-byte units per second being
transferred from swap space into memory and the
0.0 in the bswot/s column indicates that no 512-byte units per
second are being transferred from memory out to swap space. It is not unusual to see a moderate amount of
paging in: some objects are brought into memory only upon demand, that is, when they are actually referenced.
However, it is generally undesirable to see any significant amount of paging out, because it is likely that some high-
performance processors will become stalled waiting for slow disk accesses to complete. Paging activity is an
indication that the total memory footprint of all processes executing on the system exceeds the amount of physical
memory available. The appropriate remedy is to add physical memory, if such is available through Instant
Capacity or there is unassigned memory in a vPars environment. The other way to reduce memory pressure is to
trim the workload imposed on the system, perhaps by redirecting users to some other server or reconfiguring the
memory requirements of the application (for example, by reducing the size of the Oracle SGA).
Locinfo to illustrate pstat_getlocality() call
The pstat_getlocality(2) system call can be invoked by application programs to gain information about
memory distribution in NUMA platforms. The
locinfo program gives an example of usage. The full source code
for
locinfo is given in appendix . Information about the attributes of cells in NUMA platforms is available in
the
5
HP Superdome 2 Partitioning Administrator Guide.
--- System wide locality info: ---
index ldom physid type spus total free float used
0 0 0 C{S}LM 6 55.94G 24.68G 0 31.26G
1 1 1 C{S}LM 6 55.93G 28.98G 0 26.95G
2 2 2 C{S}LM 6 55.94G 28.95G 0 26.99G
3 3 3 C{S}LM 6 63.94G 38.02G 38.02G 25.92G
4 -1 -1 ILM 0 24.00G 7.49G 0 16.51G
----- ----- ----- -----
255.75G 128.12G 38.02G 127.63G
The type of the memory locality is either interleaved memory (ILM) or one of three types of local memory: cell local
memory (CLM) for hardware platforms having a cellular architecture, or socket local memory (SLM) or blade local
memory (BLM) for hardware platforms composed of blades. From the operating system's perspective, CLM and
SLM are equivalent -- both permit the fastest possible memory accesses by local processors -- and so are marked
"
C{S}LM" in the output. Blade local memory is interleaved between the two sockets on the blade, but not across
multiple blades.
This system has four CLM localities corresponding to the four cells numbered 0, 1, 2, and 3. The locality domain
identified as -1 is ILM, composed of memory drawn from the three base cells. Cell 3 is a floating cell, and so
contains only local memory; it does not contribute to the memory interleave.
This particular system has 64 GB of physical memory on each of the four cells. Cells 0, 1, and 2 are base cells and
were configured to have
7
/
8
of their memory (that is, 56 GB) as CLM leaving
1
/
8
(8 GB) as ILM. (Some memory is
always used by firmware, and memory pages showing errors may be deconfigured, so the amount of memory
available to the operating system is somewhat less than the nominal capacity.)