If a process has to wait for memory pages, system performance is impacted. The system keeps a pool of available pages just for this. To see if we need to adjust minfree and maxfree, first find out what they are set to now:
vmo -o minfree vmo -o maxfree
Then, run vmstat and watch the fre column. If the fre column reaches minfree, raise the minfree and maxfree parameters. If the fre colum is consistantly above maxfree, then no tuning is necessary.
/usr/samples/kernel/vmtune -f 120 -F 128
vmo -p -o minfree=120 vmo -p -o maxfree=128
vmo -p -o minfree=960 vmo -p -o maxfree=1088
NOTE: Cerner recommends minfree = 120 * # CPUs and maxfree = minfree + ( 8 * # of CPUs) for AIX up to 5.3.