[Soekris] No HD DMA? (Was: Harddisk slow)
rebehn at ant.uni-bremen.de
Tue Jan 30 07:50:53 UTC 2007
Szentiványi Mátyás wrote:
> Hi Heinrich!
> I think it's almost the best speed you can achieve from the device. I've
> got the same type of Soekris with a SAMSUNG HM080HC HDD (which is the
> This HDD supports perpendicular recording
> (http://en.wikipedia.org/wiki/Perpendicular_recording). Higher data
> recording density means bigger transfer speeds.
> I'm running Gentoo Linux with kernel version 2.6.18 on the Soekris.
> Here are the results:
> soekris ~ # dd if=/home/100mb.dat of=/dev/null
> 204800+0 records in
> 204800+0 records out
> 104857600 bytes (105 MB) copied, 7.7067 seconds, 13.6 MB/s
> (The CPU usage is also 100% here while the reading is done. I've been
> using ext3 filesystem.)
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)?
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