On Thu, 2002-10-03 at 13:24, Justin Kremer wrote:
> I just moved my system from a SCSI drive to an IDE drive. (I know I'm
> moving the wrong direction for performance, but I don't care about that
> right now)  
> All seemed to work out fine.  After a bit ot troubleshooting and playing
> trick-the-grub a bit my system boots and the bootloader even points to a
> kernel that exists.  Now my problem is that since the HDD swap, whenever I
> have moderate HDD usage, my CPU usage goes to 100%.  
[snip]
> running debian with kernel 2.4.19
> I tried installing RH7.3 with kernel 2.4.18-10 onto one of the drives and
> it does not have the same problem there.  I would, however, like to
> contine using debian without having to reinstall the system.  
> Any ideas of what would be causing this behavior?

Debian tries to be a bit safer when it comes to performance settings, so
the stock debian kernel will not enable DMA on the hard drive.  This
massively impacts CPU usage (one of many reasons why IDE used to suck
more than...er, let's not go there).

You can just turn it on with `hdparm -d1 /dev/hdX' or do `echo
using_dma:1 > /proc/ide/hdX/settings'.

You need to put this in an init script of some kind if you want this to
be a permanent change.  Debian provides the `hwtools' package, which
provides a nice place to put those commands (/etc/init.d/hwtools).

-- 
 _  _  _  _ _  ___    _ _  _  ___ _ _  __   I have doobie in my funk
/ \/ \(_)| ' // ._\  / - \(_)/ ./| ' /(__   
\_||_/|_||_|_\\___/  \_-_/|_|\__\|_|_\ __)  
[ Mike Hicks | http://umn.edu/~hick0088/ | mailto:hick0088 at tc.umn.edu ]
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