关于SATA硬盘在2.6.18内核下速度问题

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[root@test01 ~]# hdparm /dev/sda

/dev/sda:
IO_support   =  0 (default 16-bit)
readonly     =  0 (off)
readahead    = 256 (on)
geometry     = 19457/255/63, sectors = 312581808, start = 0
[root@test01 ~]# hdparm -t /dev/sda

/dev/sda:
Timing buffered disk reads:  182 MB in  3.03 seconds =  60.08 MB/sec
[root@test01 ~]# uname -r
2.6.18-8.el5
[root@test01 ~]#

SATA硬盘的速度为何这么小？  
硬件信息
SMBIOS 2.31 present.
47 structures occupying 1946 bytes.
Table at 0x000EFA20.

Handle 0x0000, DMI type 0, 20 bytes.
BIOS Information
        Vendor: IBM
        Version: 2CKT14AUS
        Release Date: 06/15/2004
        Address: 0xE4AC0
        Runtime Size: 111936 bytes
        ROM Size: 512 kB
        Characteristics:
                PCI is supported
                PNP is supported
                APM is supported
                BIOS is upgradeable
                BIOS shadowing is allowed
                ESCD support is available
                Boot from CD is supported
                EDD is supported
                ACPI is supported
                USB legacy is supported
                AGP is supported
                LS-120 boot is supported
                Smart battery is supported
                BIOS boot specification is supported

Handle 0x0001, DMI type 1, 25 bytes.
System Information
        Manufacturer: IBM
        Product Name: 8126D1C
        Version: ThinkCentre A50
        Serial Number: 99B0324
        UUID: 0064951B-D763-0010-A583-92314A8FA8DF
        Wake-up Type: Power Switch

865芯片支持SATA接口，硬盘为st3160815as  7200、8、  300mb/s