Date: Thu, 03 Nov 94 16:27:59 GMT
From: Martin AT snsystems DOT co DOT uk (Martin Day)
Reply-To: Martin AT snsystems DOT co DOT uk
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: Disk I/O rates with DJGPP
Lines: 31


I've done some benchmarking on disk i/o rates using various compilers
and dos extenders and have come up with the following results :

Time to read a 32 Mbyte file in block sizes of 4k and 32k using
fread() :

System     4K   32K
===================
Native     21    16   Turbo-C compiler - 16 bit code
X32        22    17   Watcom C 9.5 with X32 DOS extender
DOS4GW     24    21   Watcom C 9.5 with DOS4GW DOS extender
DJGPP      27    27   GCC with GO32 ( 1.12.maint2 )
===================

Values in the table are time in seconds to read the entire file. 
This is running on a 100MHz Pentium, 48Mbytes RAM using a SCSI hard
drive running QEMM 7.03 with DPMI services.

X32 is a DOS extender from Flashtek Inc.

DOS4GW is the DOS extender supplied with Watcom C 9.5.

I think the results show that the 4k buffer is not the only reason
for slow file i/o with GCC.  There's probably some inefficiency in
the real mode interrupt call to DOS too.

Any comments ?

-- 
Martin                                         martin AT snsystems DOT co DOT uk