From: Aurel Balmosan (aurel@uni-paderborn.de)
Date: 05/04/93


From: aurel@uni-paderborn.de (Aurel Balmosan)
Subject: [Q]: raw hd-device speed
Date: 4 May 1993 15:03:33 GMT

I have a Problem with my hard disk. Any benchmark (under dos), the
cmos-setup program and others show a raw disk speed of 873.6KBytes/sec.

But the maximum raw hd-device speed is about 340kBytes/sec with a cpu-use
of only 13.5 percent.

I have a 486DX33 EISA-Board, 16Bit IDE-Controler, Conner 162Mbyte hard disk,
903Tracks,8Heads,46Sector per Head.
I have tried any posible interleave value to speed up the hd-device speed under
linux. But there was no change of speed (under dos the hard disk have allways
a transfer rate of 873.6KBytes/sec).

On a 486DX50 (No EISA-Board), 16Bit IDE-Controler, Quantum 240M,
the hd-device speed was 810kBytes/sec. The cpu-use was 30.0 percent!

[QUESTION]
- Why is the speed of my hard disk under linux less than the speed under dos?
- Is the 486DX50 faster because of the harddisk type?
  Or because the 486DX50 can handle the read/write interrupt faster, so that the
  hard disk continues reading without any delay?
- How can I speed my hd-device up? (any timer-values, or interrupt handler to
  change ?).
- Is it posible to use the BIOS functions to read from disk?

-- 
        Alexandru-Aurel Balmosan                aurel@uni-paderborn.de
        University of Paderborn (Germany)