squid file system problem

i am trying to configure squid with reiserfs partition with 8gb while after editing squid.conf file i and written at
cache_dir reiserfs /cache 8000 18 256
and trying to start the squid and i am not able to start the squid and i am getting an error as

FATAL: Unknown cache_dir type 'reiserfs'

Squid Cache (Version 2.4.STABLE7): Terminated abnormally.
CPU Usage: 0.006 seconds = 0.004 user + 0.002 sys
Maximum Resident Size: 0 KB
Page faults with physical i/o: 220
Aborted

can any one help me out for this, i have created 8gb partion and with mkreiserfs i have formated to reiserfs, and mounted it. my hdd is scsi and size is 18gb. i thank you all who are participating here.

i hv created /cache dir with 8GB partition with reiserfs file system, on my 18gb scsi hard disk and it is showing as with df
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/sda6 ext3 1004024 120816 832204 13% /
/dev/sda1 ext3 101089 15072 80798 16% /boot
none tmpfs 515248 0 515248 0% /dev/shm
/dev/sda3 ext3 6048352 1226956 4514156 22% /usr
/dev/sda7 ext3 497829 44789 427338 10% /var
/dev/sda2 reiserfs 7164764 32840 7131924 1% /cache

this is my disk details, with default configuration for cache dir as
cache_dir ufs /var/spool/squid 100 16 256
this configuration is working,
why i am trying with reiserfs is to get better performance.

can u check it and give me a solutions for my squid to recognise my reiserfs partition.