ahd(4) poor performance

[Volodymyr Kostyrko]

Justin T. Gibbs пишет:
> --On Thursday, June 22, 2006 12:16 AM +0300 Volodymyr Kostyrko 
> <arcade at synergetica.dn.ua> wrote:
> 
>> Hi all.
>>
>>    I have:
>>
>> ahd0: <Adaptec (Dell OEM) 39320 Ultra320 SCSI adapter> port
>> 0xdc00-0xdcff,0xd800-0xd8ff mem 0xdfbfe000-0xdfbfffff irq 66 at device
>> 7.0 on pci3
>> ahd0: [GIANT-LOCKED]
>> aic7902: Ultra320 Wide Channel A, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs
>> ahd1: <Adaptec (Dell OEM) 39320 Ultra320 SCSI adapter> port
>> 0xd400-0xd4ff,0xd000-0xd0ff mem 0xdfbfc000-0xdfbfdfff irq 67 at device
>> 7.1 on pci3
>> ahd1: [GIANT-LOCKED]
>> aic7902: Ultra320 Wide Channel B, SCSI Id=7, PCI-X 101-133Mhz, 512 SCBs
>>
>>    Booting machine also results in:
>>
>> ahd0: Invalid Sequencer interrupt occurred.
> 
> This error is benign.
> 
> There have been issues reported with some recent Seagate drives and
> large queue depths.  You may get better performance if you use camcontrol
> to lower the queue depth to 63 or 32.  I believe that 32 is the default
> used by Linux.
> 
> -- 
> Justin

   Interesting.

   By default I have the following:

srv4# camcontrol tags 0:0 -v
(pass1:ahd0:0:1:0): dev_openings  1
(pass1:ahd0:0:1:0): dev_active    0
(pass1:ahd0:0:1:0): devq_openings 1
(pass1:ahd0:0:1:0): devq_queued   0
(pass1:ahd0:0:1:0): held          0
(pass1:ahd0:0:1:0): mintags       2
(pass1:ahd0:0:1:0): maxtags       255

   Raising this to higher values provides better perfomance:

@1:

 > dd if=/dev/zero of=somefile count=20480
20480+0 records in
20480+0 records out
10485760 bytes transferred in 1.114188 secs (9411123 bytes/sec)

@2:

 > dd if=/dev/zero of=somefile count=20480
20480+0 records in
20480+0 records out
10485760 bytes transferred in 0.402884 secs (26026747 bytes/sec)

   Raising it further doesn't help anyway. And it still behaves not so 
fast as Linux.

-- 
[WBR], Arcade.