Re: Odd IDE performance drop 2.4 vs 2.6?

[Ondrej Zary <linux@rainbow-software.org>]

Alan Cox wrote:
> On Mer, 2005-06-15 at 20:15, Ondrej Zary wrote:
> 
>>Now I've tested it with preempt disabled and nothing has changed. When 
>>fiddling around with hdparm, I got about 16MB/s max. with 2.6.12-rc5. 
>>With 2.4.31, I got about 21MB/s when just the DMA was enabled 
>>(read-ahead and multcount set to 0 - changing them does not make almost 
>>any difference).
> 
> 
> multcount is only used for PIO so that would be expected. Similarly the
> block readahead should matter but not anything drive level.
> 
> If you compare the hdparm data are both 2.4 and 2.6 selecting the same
> IDE modes ?

This is in my init scripts:
/usr/sbin/hdparm -u1c1k1 /dev/hda /dev/hdc /dev/hdd 1> /dev/null
It selects UDMA2 mode in both 2.4 and 2.6.

hdparm -i /dev/hda shows exactly the same output in both 2.4 and 2.6:

/dev/hda:

  Model=WDC WD300BB-00AUA1, FwRev=18.20D18, SerialNo=WD-WMA6W1847372
  Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
  RawCHS=16383/16/63, TrkSize=57600, SectSize=600, ECCbytes=40
  BuffType=DualPortCache, BuffSize=2048kB, MaxMultSect=16, MultSect=16
  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=58633344
  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
  AdvancedPM=no WriteCache=enabled
  Drive conforms to: device does not report version:

  * signifies the current active mode

-- 
Ondrej Zary