AMM activirty from v$memory_resize_ops

 Dear All, the server spec as below: 1) DB Std 11gR1 (11.1.0.7.0)
2) SunOS 5.10 Generic_141414-10 sun4v sparc SUNW,SPARC-Enterprise-T5120
3) 4G RAM, 1 Socket CPU (32 vcpu)

I've turned on the AMM as below:
1) memory_max_target = 2G
2) memory_target = 1664M

I found the 2 components 'shared pool' and 'DEFAULT buffer cache' from v$memory_resize_ops quite frequent adjusted themselves, and only these 2 components are interchanged the value. I'm wonder if it is a healthy sign or need further increase the memory target ?

eg:
START_TIME                DB_CACHE FINAL_SIZE    Share_Pool FINAL_SIZE
3/31/2010 3:20:50 PM    402653184                        671088640
3/31/2010 10:02:51 PM  402653184                        637534208
3/31/2010 10:02:51 PM  436207616                        620756992
4/1/2010 10:03:17 PM    452984832                        603979776
4/2/2010 4:56:44 PM      469762048                        587202560
4/2/2010 10:01:40 PM    486539264                        570425344
4/3/2010 11:41:38 AM    503316480                        553648128


Thanks,
Keng Heng. Chan