2940 2.0.32 and odd behaviour

[Doug Ledford]

On 04-Dec-97 Mike Isely wrote:
>On Thu, 4 Dec 1997, Jason Venner wrote:
>
>> 
>> 
>> I recently did a major upgrade on my 2.0.24 linux box.
>> I went from a P150 to a k6-200 and 2.0.24 to 2.0.32
>> 
>> I now have some very odd disk behaviour. Disk IO seems slower, and
>> tasks seem to run at variable speeds.
>> for instance, I like to play xboing, it used to be very smooth, now
>> the ball slows down and speeds up as it goes.
>> 
>> It is very odd. I did enable tagged queuing and SCB paging.
>> 
>> Is this unrelated to my disks?
>> 
>
>Perhaps something's running around in the kernel for longer periods with
>interrupts turned off.  What does "top" show you?  Are you spending lots
>of time in kernel mode? 
>
>I remember there was some talk about this a while ago with the SCSI
>driver.  Ring any bells anyone? 

Yeah, with SCB paging and tagged queueing enabled, the machine can spend a
significantly larger period of time doing things like SCSI command
completion processing.  Part of this occurs with interrupts off, so you may
see some delays in other interrupts while it takes place, resulting in
choppy behaviour for things like X windows or other video intensive
applications.  It's one of the things on my todo list, but not really a high
priority since it doesn't effect the overall operation of the driver (and
happens to be somewhat tied into my SMP-friendliness todo item).

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E-Mail: Doug Ledford <dledford at dialnet.net>
Date: 04-Dec-97
Time: 14:36:26
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