Re: Hard disk access causes high CPU load

[Shyamal Prasad <shyamal.prasad@sbcglobal.net>]

    "Balazs" == Balazs Javor <jb3@freemail.hu> writes:

    Balazs> Hi, How can I find out whether the hard disks in my Woody
    Balazs> box are using the best possible DMA mode (or any DMA at
    Balazs> all)?

    Balazs> Allthough I have a relativly slow machine (VIA C3 800 +
    Balazs> 256MB), I have an ATA100 controller (VIA PL133) and two
    Balazs> Seagate Barracuda IVs.  So they should be relatively fast
    Balazs> and use not much CPU, or shouldn't they?

Yes, and that is a pretty fast machine anyway ;-)

    Balazs> But on my 2.4.18 machine it can take ages to transfer
    Balazs> large file between them. And while the file transfer takes
    Balazs> place the CPU usage is above 90% and XFree becommes
    Balazs> _extremely_ sluggish.  Even if I try to move the mouse
    Balazs> there are stops and a quite large lag...

    Balazs> Is this normal, or do I need to set up something
    Balazs> differently?

It's not normal, and I'd bet you don't have DMA on.

apt-get install hdparm
hdparm -i /dev/hda

should get you started, along with 'man hdparm.' Also, installing the
'hwtools' package gives you a nice /etc/init.d/hwtools file in which
to do all the hdparm operations at boot up once you know what you
need.

Cheers!
Shyamal


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