Most modern drives support DMA, and the Linux IDE driver will use DMA if a device supports it. To check if a device is using DMA on a Linux host, you can cat /proc/ide/piix:
$ cat /proc/ide/piix
Controller: 0
Intel PIIX4 Ultra 100 Chipset.
--------------- Primary Channel ---------------- Secondary Channel -------------
enabled enabled
--------------- drive0 --------- drive1 -------- drive0 ---------- drive1 ------
DMA enabled: yes yes yes yes
UDMA enabled: yes yes yes yes
UDMA enabled: 5 5 5 5
UDMA
DMA
PIO
The output contains a “yes” or “no” to indicate if DMA is enabled, and a line to indicate which DMA mode is in use. If for some reason DMA isn’t being used with a device, you can use hdparm to enable it.