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Performance in DOS is terrible #7332

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nielsmh opened this issue Mar 5, 2019 · 3 comments
Closed

Performance in DOS is terrible #7332

nielsmh opened this issue Mar 5, 2019 · 3 comments
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good first issue Good for newcomers regression It used to work, and now it's broken.

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@nielsmh
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nielsmh commented Mar 5, 2019 •
edited

Version of OpenTTD

#7331 test build
DJGPP (DOS) build running in Windows 95 DOS box on a Via EPIA-VE5000 board with 128 MB RAM installed. (No VM or emulation.)

openttd.cfg:

blitter = 8bpp-optimized
support8bpp = hardware
resolution = 640,480

Expected result

Playable framerates.

Actual result

image
Framerate is very low and game is not really playable, despite no individual performance measurement being bad. Something slow is happening between GameLoop and the video output.

Steps to reproduce

  1. Obtain some old hardware
  2. Install a long out of support operating system
  3. Figure out a way to transfer files from the internet to the system
  4. Run the game
@TrueBrain TrueBrain added good first issue Good for newcomers regression It used to work, and now it's broken. labels Mar 5, 2019
@nielsmh
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nielsmh commented Mar 5, 2019

A possible suspect for the cause might be the timing routine, except then fast-forward mode should still work (which it doesn't):

OpenTTD/src/video/allegro_v.cpp

Lines 464 to 479 in f52e5a4

#if defined(UNIX) || defined(__OS2__) || defined(DOS)
# include <sys/time.h> /* gettimeofday */
static uint32 GetTime()
{
struct timeval tim;
gettimeofday(&tim, NULL);
return tim.tv_usec / 1000 + tim.tv_sec * 1000;
}
#else
static uint32 GetTime()
{
return GetTickCount();
}
#endif

@Gymnasiast
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Don't take this the wrong way (I don't want to tell you how to develop OpenTTD), but why does OpenTTD still support operating systems this old? Isn't it a noticeable burden on development? (At OpenRCT2, we even dropped XP because of compiler support and missing APIs, which might be the other extreme.)

@TrueBrain TrueBrain mentioned this issue Mar 19, 2019
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@TrueBrain
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@Gymnasiast: in simple terms, because we can :D But .. we are planning on dropping it for other reasons ;)

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good first issue Good for newcomers regression It used to work, and now it's broken.
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@nielsmh @Gymnasiast @TrueBrain