Subject: Re: raidframe queue
To: Mihai CHELARU <kefren@netbsd.ro>
From: Greg Oster <oster@cs.usask.ca>
List: current-users
Date: 04/04/2006 08:51:13
"Mihai CHELARU" writes:
> Hi,
> 
> I initialized a raid device with fifo queue (size 100). I tried to change it 
> after that to sstf, size 200. Still after reboot & reconfigure, raidctl -s 
> raid0 shows:
> 
> raid# raidctl -s raid0 | grep Queue
>    Queue size: 100, blocksize: 512, numBlocks: 230344992
>    Queue size: 100, blocksize: 512, numBlocks: 230344992
>    Queue size: 100, blocksize: 512, numBlocks: 230344992
>    Queue size: 100, blocksize: 512, numBlocks: 230344992

Did you re-do 'raidctl -I'?  'raidctl -s' reads directly from the 
component label, so if you configured before with a queue of 100, 
that's what it'll still be reading.

> How can I check what's the queueing strategy, and why is not changed 
> acording to config file ? 

Unfortunately, you can't check, but it will be configured according 
to the config file...

> I'm not using autoconfigure, btw.

(and, for the record, autoconfigure doesn't keep track of the queue 
being used, and assumes FIFO.)

(Also.... you should see exactly zero difference between a queue 
length of 200 and a queue length of 100.  I suspect a queue length of 
20 would have the same performance as well... (less than that, and 
you *might* notice a difference, depending on the exact IO pattern..))

Later...

Greg Oster