Re: poor ATA disk speed with ICH2

Kevin Oberman wrote:

>>>While the test is running, the disk being written to "sings" with the
>>>frequency somewhat dependent on the size of the write. On read, I get
>>>silence. When I copy my full disk (if=3Dad0 of=3Dad2), I can clearly he=
>>
>>ar
>>
>>>the sound of the actuator moving the heads constantly toward the end of=
>>
>>>the backup. I assume that they are being returned to track 0 on a
>>>repeated basis.
>>
>>There should be no seeks on a lone write to the raw disk, if there is=20
>>you have HW problems as the driver doesn't issue any seeks at all then.
>>
>>What disks are this BTW ?
> 
> 
> This was RELENG_5 on the 6th at 22:55 UTC. cvsup from my local mirror,
> so it may have been up to about 70 minutes old.
> 
> The "singing" only happens when running V5. I have no such sound when I
> do the same thing with V4. 

I have no idea, there is nothing in the ATA driver that does extra 
seeking, so the seek behavior must originate somewhere else, ie 
something else issues disk requests besides your dd. You could 
instrument the code and have it write out all LBA's it writes to on ad2 
to see what gets sent to the disk.

> The disk is an Toshiba MK4019GAX. 40 GB ATA100 5400RPM. I get the same
> performance, though, when using an IBM (now Hitachi) 40GB, ATA100
> 5400RPM drive. What I am seeing looks a lot like what Bjoern was seeing,
> so it's not unique to this system.

Hmm, do you have write cache en/dis-abled ?

Just for the fun of it I dd'ed to from my laptop disk through the fs 
though as I want to keep my data, but that shoudl only make performance 
worse. Its an ich4 but that uses the same code as the ich2.

atapci0: <Intel ICH4 UDMA100 controller> port 
0x1860-0x186f,0x376,0x170-0x177,0x3f6,0x1f0-0x1f7 at device 31.1 on pci0
ad0: 76319MB <TOSHIBA MK8025GAS/KA023A> [155061/16/63] at ata0-master 
UDMA100

  dd if=/dev/zero of=fil bs=512  (24474468 bytes/sec)
  dd if=/dev/zero of=fil bs=1m   (25091961 bytes/sec)

thats copying for ~30s as well (reading doesn't make sense here).

Both are close to what that disk can do, so there is nothing in the 
driver thats prohibiting reaching the disks performance...

-Søren