High interrupt CPU usage in top

[Matthew Dillon]

:It does boot with DMA turned on, unless I am missing something? The 
:WDMA2 drive is the old CD drive, the UDMA33 drive is the hard disk. :-)

    Yes, that is so... but I'm not entirely sure that it actually uses
    those settings when you have a configured slave without a master.

    The dd command you ran isn't really a good test.  Because you didn't
    specify a block size, dd will use 512 bytes.  Needless to say 512 byte
    transfers from the hard drive are going to be cpu-bound and most of the
    overhead is going to be in command setup and tear down.  Try 32K
    transfers:

    dd if=/dev/adX of=/dev/null bs=32k

    It should be < 1%.

					-Matt
					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>