From: Vincent Cunniffe (vincent at domain beacon.ie)
Date: Wed 19 May 1999 - 10:17:25 IST
> Seening linux.com is now live, its got a tuneup page. One of
> which is hdparam's (hard disk parameters).
>
> So I tried it out on my server here.
>
>Before: (dma and 32bit are turned off, i.e. default)
> [root at domain portia:/var/log]#hdparm -t /dev/hda
>
> /dev/hda:
> Timing buffered disk reads: 16 MB in 2.39 seconds = 6.69 MB/sec
>
>Turn on 32bit acccess:
> [root at domain portia:/var/log]#hdparm -c 1 /dev/hda
>
> /dev/hda:
> setting 32-bit I/O support flag to 1
> I/O support = 1 (32-bit)
>
>Now another test:
> [root at domain portia:/var/log]#hdparm -t /dev/hda
>
> /dev/hda:
> Timing buffered disk reads: 16 MB in 0.34 seconds =47.06 MB/sec
> [root at domain portia:/var/log]#hdparm -t /dev/hda
>
> /dev/hda:
> Timing buffered disk reads: 16 MB in 0.34 seconds =47.06 MB/sec
>
>Anyone else seen this ? I can't do the same on another machine...
>hda: QUANTUM FIREBALL_TM2110A, 2014MB w/76kB Cache, CHS=1023/64/63, DMA
Impossible speeds : even a full UDMA bus in burst mode can only provide
33MB/s throughput, and there isn't an IDE drive in the world that can
actually provide data at that rate, let alone for a sustained 16MB burst.
There has to be some serious software buffering in there somewhere...
Pity though :-)
Vin
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