The performance of the
Scoring Accelerator for Oracle can be affected by altering the Degree
of Parallelism (DOP) setting. In a Real Application Clusters (RAC)
environment the parallel processes are distributed among the available
database instances when the chosen DOP exceeds the expected capabilities
of a single node. In environments with mixed workloads and multi-concurrency,
you should rely on the parallelism provided by the Oracle database.
However, to achieve maximum throughput for dedicated Scoring Accelerator
operations, you might consider adjusting the DOP setting.
Because Oracle and SAS
use separate threads during execution, improvements throughput diminish
for DOP values that are greater than half the total number of cores
available. For example, if you have 128 cores total available for
all instances, a DOP greater than 64 is not likely to yield improved
performance. Setting the DOP up to this maximum level assumes that
the system is solely dedicated to running the SAS Scoring Accelerator.
For a mixed load system, a lower DOP value might be more appropriate.
Along with the DOP,
adjusting the value of the internal parameter _parallel_load_bal_unit
can also be beneficial to distributed performance. This parameter
affects the number of threads allocated for a given RAC instance before
a parallel query engages additional instances. Similar to DOP, setting
_parallel_load_bal_unit parameter beyond half the core total per instance
is not likely to be beneficial.
CAUTION:
_parallel_load_bal_unit
is an internal Oracle parameter.
Do not use this parameter
unless instructed to do so by Oracle Support. Modifying this parameter
might be harmful.