ACHI support
Alan Cox
alan at lxorguk.ukuu.org.uk
Wed Aug 22 16:57:06 UTC 2007
> Create /etc/modprobe.d/atapienable containing
>
> options ibata atapi_enabled=1
This one shouldn't be needed, the default is atapi enabled since 2.6.18
or so.
>
> Create /etc/sysconfig/mkinitrd containing
>
> MODULES="ahci"
>
> to ensure that future kernel initrds will contain the ahci module.
Ah I was trying to work out why it didn't "just work" - your default
initrd didn't have the AHCI driver. I thought 2.6.22 should be working!
>
> - "hdparm -tT /dev/sda" doesn't show much difference in performance
> between compatibility and AHCI modes. Where should I expect to see a
> performance difference, and are there any other settings needed to help
> it along?
AHCI improves performance under load - the cost to issue a command is
lower than with traditional IDE interfaces for one, and if your drive has
NCQ support we can give the drive multiple commands at a time, and the
drive is able to fulfill them out of order according to things like head
position. As the drive has a list of work to do it can do it more
efficiently based on its detailed knowledge of the media.
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