[Soekris] No HD DMA? (Was: Harddisk slow)
mstone+soekris at mathom.us
Tue Jan 30 12:49:49 UTC 2007
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
>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.
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