On Fri, Apr 11, 2003 at 06:37:34PM +0200, Wojciech Puchar wrote:
> i bought new CD-RW. older was SCSI (but refused to record any CD-RW
> since 1/2 year thats the reason i bought new) new is IDE.
> 
> cd1 at atapibus0 drive 0: <HL-DT-ST GCE-8520B, , 1.00> cdrom removable
> cd1: 32-bit data port
> cd1: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2 (Ultra/33)
> cd1(pciide0:1:0): using PIO mode 4, Ultra-DMA mode 2 (Ultra/33) (using DMA
> data transfers)
> 
> 
> the question is - is it normal so huge CPU load? older was using about
> 5% with 4x speed. this can't record over 16x without underrun. at 12* it
> uses about 60% CPU while more are system than user.
> 
> is IDE so bad in that case? it is using Ultra/33 mode, same as hard drive
> which is able to give 16MB/s

Doesn't it downgrade to a lower mode ?
Also, Are you burning data or audio CDs ? audio uses blocks which are
not multiple of 512, and sometimes cause problems with ATAPI (most IDE
controllers are designed for transfers which are multiple of 512 bytes).
Also ATAPI will always be a bit worse than SCSI, because the 16-bit command
has to be sent though PIO.

While you're burning, can you watch the interrupt rates with systat vm ?

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 24 ans d'experience feront toujours la difference
--