2.4: high system load with SG_IO on IDE-SCSI: PIO?

From: Matthias Andree (matthias.andree@gmx.de)
Date: Sun Mar 09 2003 - 09:49:09 EST

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Hi,

I have seen readcd ("sg driver 3.2.0") use 96% system time for a readcd
-c2scan on IDE-SCSI (ATAPI CD-ROM, Plextor PX-4824TA 1.04, UDMA/33),
Linux 2.4.19+SuSE patches (k_athlon-2.4.19-167).

...
ioctl(3, 0x2285, 0xbfffec20) = 0
...

The same application on a real SCSI-device with SCSI host adaptor
(aic7xxx FWIW) is way below 5% system CPU time.

Might SG_IO use PIO on ATAPI CD-ROMs? If so, are there patches to enable
DMA? Is this at all possible with SG_IO?

I find 96% system load is way too high for modern hardware. (Duron/700
that is, VIA 82C686a).

Thanks in advance,

-- 
Matthias Andree
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Next message: Craig Schlenter: "[OOPS] oops with linux-2.5.64 + cset-1.1068.1.17-to-1.1166.gz"
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