Re: Slow scsi performance under 1.3.77
Michael Neuffer (neuffer@goofy.zdv.uni-mainz.de)
Sat, 23 Mar 1996 18:17:18 +0100 (MET)
On Fri, 22 Mar 1996 yuri@poly21.rgti.com wrote:
> I'm having performance problems with the scsi subsystem under kernel
> 1.3.77. I have two drives: a Seagate ST32550N and Quantum XP34301 on a DPT
> SmartCache III controller. Copying a 33mb file from one location to another
> on the same disk takes about 27 seconds - pretty slow for 7200 RPM drives.
> Here is where it gets even weirder. Copying a 33mb file from one drive to
> another also takes about 27 seconds. Correct me if I'm wrong but shouldn't it
> take about half the time? I've also tried running several disk benchmarks
> (the Byte Unix bench and bonnie) - they all give rather low scores - about
> half the throughput I've seen on the same drives under BSD. Running the
> benchmarks in parallel on separate disks results in an ADDITIONAL 40-50%
> reduction in throughput.
[...]
> Recently i've tried substituting a Tekram DC-390 controller for the
> DPT. Separate drives work ok - but when there is heavy disk activity on
> both drives I get the following message repeated over and over for both
> drive id's:
>
> scsi : aborting command due to timeout : pid 6561, scsi0, channel 0, id 2, lun 0 Write (10) 00 00 2c 0a ec 00 00 16 00
> --------------------------------------------------------------------------
> scsi0 : AM53C974_abort called -- trouble starts!!
> AM53C974 register dump:
> IO base: 0xfc00; CTCREG: 0x0000; CMDREG: 0x44; STATREG: 0x10; ISREG: 0xc4
> CFIREG: 0x80; CNTLREG1-4: 0x57; 0x40; 0x18; 0x44
> DMACMD: 0x00; DMASTC: 0x0400; DMASPA: 0x1775c00
> DMAWBC: 0x0000; DMAWAC: 0x1776000; DMASTATUS: 0x00
> ---------------------------------------------------------
> scsi0: aborting disconnected command
>
> HEEEEEEEEEEEEEEEEEEELLLLLLLLLLLP!!!!!!!
Try to go back to a somewhat older kernel (1.3.59 or so). The current
kernels have problems in the IO subsystem which cause lots of command
aborts and resets. Those aborts and resets are probably the cause for the
slow operation of your drives.
Mike
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