Re: [preview] Latest AMD & VIA IDE drivers with UDMA100 support

[Vojtech Pavlik]

On Sun, Jan 21, 2001 at 10:51:12AM +0000, Alan Chandler wrote:
> On Sat, 20 Jan 2001 20:18:34 -0500 (EST), you wrote:
> 
> 
> >that's not the topic: Andre's talking about pci-clock-based timing
> >constants the the driver programs into the ide controller - a matter
> >of an extra few/more nanoseconds.
> 
> I know, but when looking hard for a problem in one place and not
> finding it, it is sometimes helpful to consider other options.
> 
> I am getting errors under 2.4.0 which didn't appear in 2.2.17 - and as
> far as I could see from hdparm - both were at UDMA mode 2 (I assume
> thats what the * means - the man page wasn't very clear).  My drives
> only handle up to this mode, and I was wondering if the new driver was
> trying to run them at a mode higher than they were supposed to go.
>
> This massive difference in timing  seemed significant.

No, but to me it seems that even though UDMA2 mode is selected in the
drive in 2.2.17 (that's what the * means), the kernel doesn't use DMA,
and thus everything works in PIO4. This would well explain the speed
difference.

> >quite slow in either case, at least for modern hardware (which is 
> >all in the 20-40 MB/s range).  this looks like a PIO vs DMA difference
> >to me, not even UDMA.  of course, hdparm can tell you what mode you're in.
>
> I did discover a difference - 2.2.17 set the drives with multisector
> off, 2.4.0 was setting multisector on.

Multisector is valid only in PIO modes. If both were doing some kind of
DMA, it wouldn't change anything.

> However, I have redone the
> timing with multisector turned on in the 2.2.17 case and the
> difference is still there.
> 
> Under 2.2.17 with multisector turned on
> 
> 
> /dev/hda:
> 
>  Model=IBM-DHEA-38451, FwRev=HP8OA20C, SerialNo=SH0SH0X1795
>  Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
>  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=28
>  BuffType=3(DualPortCache), BuffSize=472kB, MaxMultSect=16,
> MultSect=16
>  DblWordIO=no, OldPIO=2, DMA=yes, OldDMA=2
>  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=16514064
>  tDMA={min:120,rec:120}, DMA modes: sword0 sword1 sword2 mword0 mword1
> mword2 
>  IORDY=on/off, tPIO={min:240,w/IORDY:120}, PIO modes: mode3 mode4 
>  UDMA modes: mode0 mode1 *mode2 
> 
> ------------------
> 
> /dev/hda:
>  Timing buffered disk reads:  64 MB in 19.88 seconds =  3.22 MB/sec
> 
> 
> Under 2.4.0
> 
> 
> /dev/hda:
> 
>  Model=IBM-DHEA-38451, FwRev=HP8OA20C, SerialNo=SH0SH0X1795
>  Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
>  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=28
>  BuffType=3(DualPortCache), BuffSize=472kB, MaxMultSect=16,
> MultSect=16
>  DblWordIO=no, OldPIO=2, DMA=yes, OldDMA=2
>  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=16514064
>  tDMA={min:120,rec:120}, DMA modes: sword0 sword1 sword2 mword0 mword1
> mword2 
>  IORDY=on/off, tPIO={min:240,w/IORDY:120}, PIO modes: mode3 mode4 
>  UDMA modes: mode0 mode1 *mode2 
> 
> ------------------
> 
> /dev/hda:
>  Timing buffered disk reads:  64 MB in  6.58 seconds =  9.73 MB/sec
> 
> 
> 
> I don't suppose the fact that my hdparm is oldish (3.6 I think) have
> any bearing on this?

No, 3.6 is OK I think. 

-- 
Vojtech Pavlik
SuSE Labs