how to eliminate swap of shmfs

sansanmei

how to eliminate swap of shmfs

our db user shmfs for large sga,but when the shmfs begin swap out ,the system load up to 90.following is the result of sar's output file.
sar -q -f sa23
11:00:00 PM runq-sz plist-sz ldavg-1 ldavg-5
11:10:00 PM 1 281 0.06 0.10
11:20:00 PM 1 284 0.07 0.10
11:30:00 PM 1 263 0.01 0.09
11:40:05 PM 0 717 91.74 52.62

sar -B -f sa23
11:00:00 PM pgpgin/s pgpgout/s activepg inadtypg inaclnpg inatarpg
11:10:00 PM 12.93 171.16 1501070 1007899 308 740313
11:20:00 PM 244.75 366.98 1500750 1033957 308 740313
11:30:00 PM 11.99 118.58 1500755 1034052 305 740313
11:40:05 PM 374.28 2109.99 1843959 749458 1361 740313

at 11:40:05 PM shmfs begin swap so load increase dramatically,
so i want to know how to avoid swap in shmfs like using ramfs.
how to user ramfs in redhat as2.1?
thank in advance.