Locality-Optimized Resource Alignment

14
Establishing vPars instances by processor and memory requirements
Suppose it is stipulated to divide the example partition into vPars of the following sizes:
Table 2. Specification for size of vPars instances
Name Number of cores Amount of memory
cow 12 48 GB
dog 4 88 GB
elk 2 16 GB
fox 2 16 GB
The first vPars instance in the table, cow, requires 12 cores, so it will not fit within a single locality. It
will, however, fit within two localities, so it should be confined to just two localities: spreading its
resources across a third locality would incur additional memory latency overhead. It is best to split
the resources evenly across the two localities: this symmetry promotes the most balanced utilization of
resources. The 48 GB of memory would be allocated in the ratio ⅞
ths
local memory and ⅛
ths
interleaved memory. The 42 GB of local memory should be distributed evenly across the two
localities, with 21 GB from each of cells 1 and 2.
The second vPars instance in the table, dog, requires 88 GB of memory, so it also will not fit within a
single locality. Once again, the strategy is to confine it within the minimum number of localities,
which is two, and divide the resources as evenly as possible between the two localities. In this case,
cells 2 and 3 each contribute 2 cores, and 35 GB and 42 GB of local memory respectively, with 11
GB of memory coming from ILM.
Here are commands that could be used to establish the configuration:
vparcreate -p cow -a cpu::12 -a mem::6144 -a cell:1:mem::21504
-a cell:2:mem::21504
vparcreate -p dog -a cpu::4 -a mem::11264 -a cell:2:mem::35840
-a cell:3:mem::43008
Alternatively, a configuration of the same size including 1 GB of floating memory on each cell could
be established with slightly different commands:
vparcreate -p cow -a cpu::12 -a mem::6144
-a cell:1:mem::20480 -a cell:1:mem::1024:floating
-a cell:2:mem::20480 -a cell:2:mem::1024:floating
vparcreate -p dog -a cpu::4 -a mem::11264
-a cell:2:mem::34816 -a cell:2:mem::1024:floating
-a cell:3:mem::41984 -a cell:3:mem::1024:floating
The commands for adding I/O to the vPars instances are not shown, because they would depend on
the I/O devices needed in each instance and the location of the available I/O in the partition. Once
again, the placement of the processors and memory usually has a greater impact on system
performance than the location of the I/O.