Space Management Coordinator memory use

I have a server with two instances; one a large application, and a small RMAN recovery catalog.  I notice that the server is very low on free memory; looking at the output from the top command, sorted by %Memory, I see this:

Tasks: 419 total,   1 running, 418 sleeping,   0 stopped,   0 zombie%Cpu(s):  0.1 us,  0.1 sy,  0.0 ni, 99.7 id,  0.1 wa,  0.0 hi,  0.0 si,  0.0 stKiB Mem : 16258680 total,   190612 free,  5265508 used, 10802560 buff/cacheKiB Swap:  8388604 total,  7615796 free,   772808 used.  2911612 avail Mem  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND40940 oracle    20   0 6267296 3.283g 3.267g S   0.0 21.2   4:26.31 ora_dbw1_ecs0340938 oracle    20   0 6281768 3.126g 3.100g S   0.0 20.2   4:15.71 ora_dbw0_ecs0340926 oracle    20   0 6250020 2.704g 2.702g S   0.0 17.4   0:49.04 ora_mman_ecs0341390 oracle    20   0 6338456 2.489g 2.471g S   0.0