Adaptec-2920 eats too much cpu time when reading from the CD-ROM

From: Florin Iucha (florin@iucha.net)
Date: Wed Dec 05 2001 - 22:01:54 EST

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Hello,

I have recently purchased a Plextor 12x CD-RW and I have attached it to
and Adaptec-2920 SCSI card. The card uses the "Future Domain Corp. TMC-18C30
[36C70]" chip.

The problem I see: when reading from the CD-RW my system becomes very
unresponsive and top reveals 90-95% of the time is spent on "system".
My CPU is AMD K6-III/500MHz with 256 Mb RAM.

When reading the same CD using the IDE DVD-ROM the time spent in system
is 5%. Also when the CD-RW is connected to the Advansys SCSI controller
the CPU usage is also negligible. The Adaptec-2920 uses IRQ 10 and does
not share it with any other board.

I notice an unusual number of interrupts in /proc/interrupts: after the
machine has been up for a couple of hours and I have written three CDs,
the statistics are:
CPU0
0: 638458 XT-PIC timer
1: 15325 XT-PIC keyboard
2: 0 XT-PIC cascade
5: 0 XT-PIC es1371
8: 1 XT-PIC rtc
9: 17004 XT-PIC usb-uhci
10: 3032143 XT-PIC fdomain
11: 58021 XT-PIC advansys
12: 2995779 XT-PIC eth0
14: 107542 XT-PIC ide0
15: 6895 XT-PIC ide1

When loading the fdomain module I get:
   scsi1: <fdomain> No BIOS; using scsi id 7
   scsi1: <fdomain> TMC-36C70 (PCI bus) chip at 0xdc00 irq 10
   Bad boy: fdomain (at 0xd08b7866) called us without a dev_id!

Is there anything I can try?

Thanks,
florin

"If it's not broken, let's fix it till it is."

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Next message: Daniel Phillips: "Re: [PATCH] Revised extended attributes interface"
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