[Prev][Next][Index][Thread]

Re: E/D vs E/L speed



>>>>> "Brian" == Brian Wimberly <brianw@scripps.edu> writes:

    Brian> Which is faster on the same hardware -- Ex. /DOS or
    Brian> Ex. /Linux?

Our CPU emulator will run at the same speed under any OS, so there are
only a few issues:

  1) How fast can Executor access the graphics hardware?

  2) How efficiently is virtual memory implemented?  (Only relevant if
     you don't have lots of memory and therefore need to page to disk).

  3) How well does the operating system do things like cache
     recently accessed hard drive contents in RAM?

Linux/X-windows loses to DOS big in (1).  If svgalib supports svga
modes on your card, Executor/Linux/svgalib should be about the same
speed as Executor/DOS.

Linux beats DOS in (2), at least if you're using cwsdpmi.exe (the free
DPMI provider we supply).  OS/2 Warp and other DPMI providers seem to
do a substantially better job of using virtual memory that cwsdpmi, so
if you're using one of those you won't see much difference moving to
Linux.  For you CS types out there, cwsdpmi uses a round-robin paging
algorithm, an algorithm which doesn't work all that well for paging.
It's on the author's long list of things to improve.

Linux does a good job of (3), although something like smartdrv under
DOS is probably similar.

In general, Executor/DOS tends to be faster because Executor has
direct video access (under many system configurations), and there's
not much speed difference in the other areas.  Your mileage may vary.

-Mat


References: