Hi again,
On Wed, Sep 5, 2012 at 5:50 AM, Rugxulo rugx...@gmail.com wrote:
On Wed, Sep 5, 2012 at 2:14 AM, Felix Miata mrma...@earthlink.net wrote:
Is FreeDOS HD access as slow as PC or MS DOS? IIUC, the latter use slow 16
bit BIOS code, which is what makes it painful for me to use compared to
running DOS apps in an OS/2 VM.
Yes, probably just as slow as it also uses the BIOS.
Is FreeDOS disk I/O in the same class as 32
64 bit operating systems speed-wise?
No, FreeDOS is pure 16-bit, but with Ultra DMA enabled and a software
cache (e.g. UIDE) can help a lot. That's about the best you can do
outside of just running under DOSEMU or similar (NTVDM).
BTW, things like DOSLFN slow down file accesses a lot, so avoid them
if possible.
Just for the record, I don't know why it's faster under DOSEMU (or
similar), probably just because the file system is slightly more
efficient or multithreaded, dunno. Or maybe these new-fangled
computers are just slow at old 16-bit code (probably). But honestly,
faster than even DOSEMU is to just use a cross compiler (which I
really hate to admit because I prefer native building). make -j4
atop Linux will definitely run faster than under native FreeDOS (which
can't multitask).
Anyways, here's a concrete example: building p7zip 9.20.1 (7za.exe
only) via G++ 4.7.1 (DJGPP 2.04 host and target) on this particular
machine:
(N.B. p7zip doesn't really build under 8.3 SFNs without some fairly
minor source patching. I did upload the changes, but I doubt most
people care. Somewhat tedious and painstaking to solve that but
nothing too too bad. Anyways )
1). native FreeDOS, no LFNs, XMGR + UIDE, built atop RDISK, HDPMI32 -r
2). native FreeDOS, same as above but with DOSLFN loaded
3). DOSEMU + FreeDOS (with its own LFNs, XMS, DPMI, etc.) atop Lucid
PuppyLinux 5.18
1). (SFN) Elapsed time: 354.050 seconds (0:05:54.050)
2). (LFN) Elapsed time: 430.840 seconds (0:07:10.840)
3). (EMU) Elapsed time: 303.190 seconds (0:05:03.190)
So, for the record, fastest to slowest is DOSEMU, native FreeDOS, and
LFN-enabled FreeDOS. But we're only talking 5 vs 6 vs 7 mins. here,
indeed quite noticeable here but nothing too horribly different.
--
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