[Soekris] No HD DMA? (Was: Harddisk slow)

[Michael Stone]

On Tue, Jan 30, 2007 at 08:50:53AM +0100, Heinrich Rebehn wrote:
>attaching the drive to a notebook via a IDE/USB converter easily yields 
>20 MB/s. So the drive *is* faster. While i could live with 8 MB/s i 
>cannot accept the high CPU usage. It seems to make the installed crypto 
>accelerator almost ineffective because the interrupts cannot be served 
>fast enough.
>I suspect that the disk is not running in DMA mode. Is there any tool to 
>verify that (like Linux's hdparm)?

If it was running without DMA it would be slower. Your CPU utilization 
would likely be lower with a larger dd block size (e.g., bs=32768) so 
that you're not making so many syscalls. This isn't an IO monster, 
though, and no amount of tweaking will make it one--if that's what you 
need, you need different hardware.

Mike Stone