SMON behavior

Today, smon has been running at the top of topsessions, and disk iowait according to TOP (Unix tool on Sun 2.7) was 65%.  The I/O went down to 7%  just a few minutes ago, and I'm not sure why but think it's tied to SMON.  Last night, I used 'alter table move' to move a bunch of tables to another space and eliminate extents.  I also rebuilt 20+ indexes residing in the tablespaces.

I have three fragmentation reports: 1) before I started moving tables, 2) after all the tables were moved, and 3) one today for grins.  These are the reports. The CHUNKS_FREE increased drastically.  If anyone can explain what SMON was doing, more importantly why, I'd be most appreciative.  PCTINCREASE is 0 on all tablespaces except SYSTEM which is 50.  Oracle is 8.1.6 64bit.

Before any changes:
TABLESPACE_NAME           TOT_SIZE   TOT_FREE   PCT_FREE   MAX_FREE   CHUNKS_FRE
------------------------- ---------- ---------- ---------- ---------- ----------

EPOXDATA                  2147483648 2053771264 95.6361771 1885413376         23
EPOXINDEX                 4294967296 4148482048 96.5893745 2098917376         17 <-
EPOXTRACK                 4294967296 3570479104 83.1316948 1307656192        361 <<-
EPOXUSER                  2147483648 1547571200 72.0643997  975638528        182 <<<-
QRXHISTORY                      8192       4096         50       4096          1
QRXTRACK                  6447693824 4300197888 66.6935808 2147479552          6
RBS                        734003200  560349184 76.3415179  506568704        349
SYSTEM                     933232640  861003776 92.2603581  610861056         14
TEMP                      1094713344 1065955328 97.3730095    7602176        995

After changes:
TABLESPACE_NAME           TOT_SIZE   TOT_FREE   PCT_FREE   MAX_FREE   CHUNKS_FRE
------------------------- ---------- ---------- ---------- ---------- ----------

EPOXDATA                  2147483648 2053771264 95.6361771 1885413376         23
EPOXINDEX                 4294967296 4113629184 95.7778931 2098917376         75 <- 
EPOXTRACK                 4294967296 3555098624 82.7735901 1276198912        391 <<-
EPOXUSER                  2147483648 1429749760 66.5779114  792137728       1412 <<<- 
QRXHISTORY                      8192       4096         50       4096          1
QRXTRACK                  6447693824 4300197888 66.6935808 2147479552          6
RBS                        734003200  560349184 76.3415179  506568704        349
SYSTEM                     933232640  761487360 81.5967346  380989440         18
TEMP                      1094713344 1065955328 97.3730095    7602176        995

Today:
TABLESPACE_NAME           TOT_SIZE   TOT_FREE   PCT_FREE   MAX_FREE   CHUNKS_FRE
------------------------- ---------- ---------- ---------- ---------- ----------

EPOXDATA                  2147483648 1136574464 52.9258728  960536576         98
EPOXINDEX                 4294967296 4113629184 95.7778931 1994059776         80 <- 
EPOXTRACK                 4294967296 3833606144 89.2580986 1276198912        679 <<- 
EPOXUSER                  2147483648 1627095040 75.7675171  555593728       2633 <<<- 
QRXHISTORY                      8192       4096         50       4096          1
QRXTRACK                  6447693824 4300197888 66.6935808 2147479552          6
RBS                        734003200  560349184 76.3415179  506568704        349
SYSTEM                     933232640  861003776 92.2603581  610861056         14
TEMP                      1094713344 1065955328 97.3730095    7602176        995