In Solaris 10 x86 Update 6, Sun introduced a new feature called VPM (Vnode Page Mapping). The VPM feature is a new method to manage the cached pages of files and is more efficient than the previous method.
You can verify that vpm is enabled by running
# echo "vpm_enable/D" | mdb -k
This would return as follows is VPM is present:
> vpm_enable/D
vpm_enable:
vpm_enable:     1

To confirm that VxFS is using the VPM feature once present please run
# echo "vxfs_use_vpm/D" | mdb -k
vxfs_use_vpm:
vxfs_use_vpm:   0
Whereas on a system where VxFS uses VPM, mdb would return:
> vxfs_use_vpm/D
vxfs_use_vpm:
vxfs_use_vpm:   1

Once VPM is enabled, you can set how much memory VPM is able to use by the following entry in /etc/system:
set vpm_cache_percent = 80
the entry above allows up to 80% of memory to be used.