[gentoo-sparc] IDE Performance - SPARC (Worse on UDMA66?)

[Derek Pizzagoni]

I've been trying to up the performance of the disks in my Ultra10, and
I'm running across something I can't quite figure out...

I have 2 identical 120GB IDE drives.  One is installed on the primary
IDE interface of the motherboard.  The other is installed on the primary
IDE interface of a Promise Ultra66 PCI/IDE card (just recently flashed
to the most-recent bios). The only other drives in the box are the stock
CDROM (which is on the secondary IDE interface of the motherboard
[hdc]), and a SCSI tape backup (which is plugged into a PCI/SCSI card).

 Here are the details:

sun ~ # hdparm -i /dev/hda

/dev/hda:

 Model=WDC WD1200JB-00GVA0, FwRev=08.02D08, SerialNo=WD-WCALA2043613
 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
 RawCHS=16383/16/63, TrkSize=57600, SectSize=600, ECCbytes=74
 BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=234441648
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4
 DMA modes:  mdma0 mdma1 *mdma2
 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5
 AdvancedPM=no WriteCache=enabled
 Drive conforms to: device does not report version:

 * signifies the current active mode

sun ~ # hdparm -i /dev/hde

/dev/hde:

 Model=WDC WD1200JB-00GVA0, FwRev=08.02D08, SerialNo=WD-WCALK1317943
 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
 RawCHS=16383/16/63, TrkSize=57600, SectSize=600, ECCbytes=74
 BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=234441648
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4
 DMA modes:  mdma0 mdma1 mdma2
 UDMA modes: udma0 udma1 udma2 udma3 *udma4 udma5
 AdvancedPM=no WriteCache=enabled
 Drive conforms to: device does not report version:

 * signifies the current active mode

sun log # hdparm /dev/hda

/dev/hda:
 multcount    = 16 (on)
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 14593/255/63, sectors = 120034123776, start = 0

sun log # hdparm /dev/hde

/dev/hde:
 multcount    = 16 (on)
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 14593/255/63, sectors = 120034123776, start = 0

As you can see, the drives are identical.  The first one comes up in
mdma2 mode, and the second one comes up in udma4 mode.  This makes
sense, since the motherboard doesn't support the faster interface (only
up to 33, right?).  What doesn't make sense is this:

sun ~ # hdparm -Tt /dev/hda

/dev/hda:
 Timing O_DIRECT cached reads:   564 MB in  2.01 seconds = 280.60 MB/sec
 Timing O_DIRECT disk reads:   46 MB in  3.04 seconds =  15.13 MB/sec

sun ~ # hdparm -Tt /dev/hde

/dev/hde:
 Timing O_DIRECT cached reads:   576 MB in  2.00 seconds = 288.00 MB/sec
 Timing O_DIRECT disk reads:   30 MB in  3.13 seconds =   9.58 MB/sec

I've run them multiple times, and it always comes out similar to above.
This is on a relatively dormant system.  Can anyone tell me why a drive
plugged into the motherboard's IDE interface (running in mdma2 mode)
would outperform the same drive plugged into an Ultra66 card (running in
udma4 mode)?  With these results, I'd be better off putting the second
drive back on the chain with the CDROM.

Thanks in advance...

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