>The only thing that looks suspect to me is your queue depth.
>You'll notice that the actual queue depth being used for your
>hard drive is 1:
>> Default Tag Queue Depth: 8
>> Tagged Queue By Device array for aic7xxx host instance 0:
>> {255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
>> Actual queue depth per device for aic7xxx host instance 0:
>> {1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
>
>I'd think it should be 8 however. The tape drive, being sequential, is
>appropriate to have a depth of 1.
>
The aic7xxx defaults to TCQ disabled. Check the top of the
"cat /proc/scsi/aic7xxx/whatever" output in the original post and it
shows TCQ is disabled. This will make it run somewhat slower, depending
on drive optimization capabilities. If the drive is lame at cmd
optimization, you won't see much improvement. Big I/O subsystems will
work best with _much_ bigger TCQ depths.
>If I look at the same specs on my AIC-7860 (pretty similar to your card),
>it looks like this at the same spot:
>
>Default Tag Queue Depth: 8
> Tagged Queue By Device array for aic7xxx host instance 1:
> {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
> Actual queue depth per device for aic7xxx host instance 1:
> {1,8,8,8,8,1,8,1,1,1,1,1,1,1,1,1}
>
>This reflects my bus with HD's at ID's 1-4 and 6, a tape drive at
>ID 0, and a DVD-ROM at 5. I've never had reason to complain about
>drive performance with this configuration. The significance of your
>255's as opposed to the 0's in my config is a mystery to me.
>
255= queuing disabled. 0=enabled (max=default?), anything in between
specifies what the queue depth will be, I think.
(See /usr/src/linux/drivers/scsi/README.aic7xxx for the truth.)
>How to fix this is another matter. I would guess that it involves
>going into the Adaptec BIOS setup utility which should require a CTRL-B
>at some point in the boot process. Dig around in there and look for
>something that might be forcing it to not assign higher queue depths
>to HD's.
The aic7xxx=taq_info bootparm described in the above README will not
work until the kernel is compiled with the aic7xxx TCQ defaulted to
enable. Even then it will only allow you to set the 1st 4 TCQ depths.
I've posted a question to the aic7xxx mail list asking why only the
1st 4, with no response received so far.
Regards,
Steve
(the above opinions are only paraphases of the voices in my head and
are not the opinons of of my employer)
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