poor ATA disk speed with ICH2

[Søren Schmidt]

Kevin Oberman wrote:

> Here are the results of my last test back in May plus tests done on a
> kernel built from sources downloaded on Sep. 6. Is that going to catch
> your fix? I don't see much difference. Do you have version number I can
> check?

Sep 6 should be fine if we are talking -current, on RELENG_5 it 
"depends" since the MFC was done on the 6'th..
> 
> Buffer	V4 Read	  V4 Write  V5 Read	V5 Write		 
> 512	 8385790  8111781    6921714	 5115853   7130873   5261294
> 1k	15457027  14865113  12330562	 7811422  12494677   7952281
> 2k	25677856  25273251  19939822	10572186  20137339  10708676
> 4k	27083255  25897711  27096896	12860586  27064850  12982472
> 8k	27079563  26033768  27097726	14416520  27017494  14497783
> 16k	27082575  Oops!	    27082273	15316924  26936316  15374888
> 32k	27080720  25908336  27100118	15816203  26977041  15853140
> 64k	27079904  26008387  27096093	16073422  26939153  15938326
> 128k	27055901  25928520  27095673	16073422
> 256k	27076467  25918950  27090967	16118789
> 512k	27045087  25987266  27077925	16006708
> 1m	27026694  25738575  27060626	15879266
> 
> Read: dd if=/dev/ad2 of=/dev/null bs=nnn
> Write:dd if=/dev/zero of=/dev/ad2 bs=nnn
> All tests run for about 30 seconds.
> All tests in single-user mode. Nothing on ad2 is mounted.
> Debug (WITNESS, INVARIANTS, malloc checking) disabled.

> 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=ad0 of=ad2), I can clearly hear
> 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 
you have HW problems as the driver doesn't issue any seeks at all then.

What disks are this BTW ?

-Søren