Re: elevator algorithm bug in ll_rw_blk.c
Vojtech Pavlik (vojtech-lists@twilight.ucw.cz)
Mon, 16 Nov 1998 11:17:01 +0100
On Sun, Nov 15, 1998 at 07:54:56PM -0500, Billy Harvey wrote:
> > You could apply a two way elevator well if you knew about the physical
> > characteristics of the drive. Unfortunately there is no way to find that out
> > for most modern drives.
>
> Hmmm, why not?
>
> root@rhino /root> hdparm -I /dev/hda
>
> /dev/hda:
>
> Model=OTHSBI AKM1230AM V , FwRev=0D0. 5 A,
> SerialNo=722H5244
> Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
> RawCHS=4200/16/63, TrkSize=40257, SectSize=639, ECCbytes=21
> BuffType=3(DualPortCache), BuffSize=128kB, MaxMultSect=16, MultSect=16
> DblWordIO=no, maxPIO=2(fast), DMA=yes, maxDMA=2(fast)
> CurCHS=4200/16/63, CurSects=4233600, LBA=yes, LBAsects=4233600
> tDMA={min:120,rec:120}, DMA modes: sword0 sword1 sword2 mword0 mword1
> *mword2
> IORDY=on/off, tPIO={min:120,w/IORDY:120}, PIO modes: mode3 mode4
>
> With that kind of knowledge, what kind of improvements could be made to
> the driver?
Because this is not true at all. Your driver doesn't have 16 heads, nor
63 sectors per tracks. Modern IDE disks have usually 2, 4 or 6 heads,
and variable number of sectors per track and the values they report are
there only to work with older software that can't do LBA.
Vojtech
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