Oracle Database Discussions

We have installed Oracle 10.2 on windows 2003. Sga_target = 1.8 GB, pga_aggregate_target = 2 GB. But the instance take 11 GB in memory, and the amount is constantly growing. In v$process we have seen that the main memory occupied by the processes Oraсle.exe (P001), Oraсle.exe (P002), etc. In all 32 processes of this type. Each of them take ~ 290 mb.On the server 16 processor cores, and as I understand it, in order to parallelize oracle make 32 systemic processes (16 cores x 2 threads per core)
How to reduce the size of memory and it does not grow even more? Will a change in the parameter PARALLEL_MAX_SERVERS = 10 can help?
now:
SQL> show parameter parallel

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
fast_start_parallel_rollback string LOW
parallel_adaptive_multi_user boolean TRUE
parallel_automatic_tuning boolean FALSE
parallel_execution_message_size integer 2152
parallel_instance_group string
parallel_max_servers integer 135
parallel_min_percent integer 0
parallel_min_servers integer 0
parallel_server boolean FALSE
parallel_server_instances integer 1
parallel_threads_per_cpu integer 2