打开光驱的dma模式

[freedom1984]

[root@localhost /]# hdparm -d1 /dev/hdc

/dev/hdc:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)


硬盘的dma倒是默认开放了
/dev/sda3:
Timing cached reads: 2716 MB in 2.00 seconds = 1358.21 MB/sec
Timing buffered disk reads: 136 MB in 3.02 seconds = 45.07 MB/sec
[root@localhost /]# hdparm -Tt /dev/sda2

/dev/sda2:
Timing cached reads: 2588 MB in 2.02 seconds = 1282.28 MB/sec
Timing buffered disk reads: 162 MB in 3.03 seconds = 53.52 MB/sec
[root@localhost /]# hdparm -Tt /dev/sda6

/dev/sda6:
Timing cached reads: 2696 MB in 2.00 seconds = 1348.60 MB/sec
Timing buffered disk reads: 124 MB in 3.01 seconds = 41.18 MB/sec