Guidelines for Configuring Virtual Partitions on Cellular Platforms

13
SPECjbb
1
0.99
0.93 0.93
0.94
0.99
0.9
0.84
0.86
0.88
0.9
0.92
0.94
0.96
0.98
1
1.02
1A(nPar) 1B(vPar) 2A 2B 3A 3B 3C
configurations
normalized bops
In configurations 3A, 3B and 3C we have 75% percentage of memory configured as cell
local memory and the remaining 25% as interleaved memory. The influence of the locality
of the CPU core assignments with respect to the associated CLM is clearly shown here. In 3B
where CPU cores and CLM are on the same cell, both the workloads exhibit just 1%
degradation (as in 1B). In the case where some or all of the assigned CPU cores were from
a different cell, the degradation becomes higher.
For example, in 3C where all the CPUs are from a different cell, the SAP SD 2-tier workload
exhibited 8% degradation whereas in the case of SPECjbb workload exhibited 10%
degradation.
II) Two Virtual Partition Runs (Layout 4) Compared with Baseline Runs and
Single Virtual Partition Runs (Layouts 1-3).
Typical customers have more than one virtual partition in a given nPartition. In some cases
there may be a potential for indirect influences on the workload performance in the
individual virtual partitions due to resource layouts that may arise due to the underlying
shared system fabric. Following are the results of running both the workloads simultaneously
in the two virtual partitions.
Results from the simultaneous runs are compared not only with the baseline (1A) but also to
similar virtual partition configurations to illustrate the point. Resource configurations that are
more localized do not tend to exhibit any further performance degradation. But
configurations that do not have resources as local do tend to exhibit additional performance
degradation.
Configuration 4A which has both the virtual partitions with localized resources performs
comparably to a similarly configured virtual partition. Configuration 4B which has both
virtual partitions configured with CLM and I/O in one cell but all CPU cores in another cell
suffers further performance degradation when compared to the single virtual partition run
(9% for SAP SD 2-tier and 12% for SPECjbb).