DOSBox 0.74 CPU Benchmark

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Re: DOSBox 0.74 CPU Benchmark

Postby BinaryDemon » 2018-12-17 @ 00:44

Is there a good method for testing how many fixed cycles a cpu can handle? Currently I'm doing Quake benchmarks at cycles=max, then I test with fixed cycles and try to approach that average fps number. I usually knock a few thousand cycles off my estimate because I think Quake uses protected mode and fairs better than realmode games. Doom is tough to use as a benchmark because you have to look for dropped frames/audio because it will continue to report higher realtics even tho it's choppy. Also I dont like using the pure CPU benchmarks (ie Speedtest) because dosbox isnt doing any graphics or audio emulator while its trying to max out the cpu.

Like my current estimate for 1.6ghz Atom cpus that were popular in cheap netbooks and thin clients is ~38000 cycles. Basically id like to relate all this data back to a fixed number of dosbox cpu cycles. Anyone have a better system?
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Re: DOSBox 0.74 CPU Benchmark

Postby Tertz » 2018-12-24 @ 02:36

BinaryDemon wrote:Is there a good method for testing how many fixed cycles a cpu can handle?


In different games the emulation speed differs. There is no accurate answer.
For practical purposes it's enough to set cycles near aproximated for the needed machines or max.

Besides games and benchmarks it's possibly to use ykhwong's version (1) which reports a number of cycles with max setting.

> Like my current estimate for 1.6ghz Atom cpus that were popular in cheap netbooks and thin clients is ~38000 cycles.

Would be interesting to add results of this CPU gotten by the test procedure.
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Re: DOSBox 0.74 CPU Benchmark

Postby robertmo » 2019-9-02 @ 16:31

Qbix wrote:Is there a huge difference ? The algorithm that determines the max speed was changed a lot between 0.74 and 0.74-2 and the 64 recompiler got a lot of changes.
However on win32 the only change is the max cycles algorithm.


I recall dosbox is configured the way that even cycles max 105% doesn't use 100% of a core but only 97% or something similar. Would it be possible to unleash all 100% on multi core cpus and leave the way it is for single core (and maybe dual core) ones only? The way you can set cycles max 108% on 4 (and more) core ones?
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Re: DOSBox 0.74 CPU Benchmark

Postby Tertz » 2019-9-03 @ 23:14

robertmo wrote:Would it be possible to unleash all 100%


There is way by fixed number of cycles. Which you may also tune manually during gaming. You'll notice stuttering in case cycles are too high. Then reduce cycles until the game will go good - that should be 100%. For every game, scene, game's and emulator's settings - appropriate cycles may differ. Ykhwong's version may show cycles in numbers when you use max setting.
You should not notice fps changes until 10-15%. So 95% and 100% cycles will look for you as same, except when cycles are too high due to background processes and you get stuttering.
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Re: DOSBox 0.74 CPU Benchmark

Postby robertmo » 2019-9-04 @ 05:47

I was writing about the internal limit in dosbox that is configured to never use 100% of your core to prevent stuttering.
But I figured out that my idea was not good cause it is not only other programs causing stuttering, but also dosbox itself when it gets more cpu hungry with same number of cycles.
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Re: DOSBox 0.74 CPU Benchmark

Postby Tertz » 2019-9-04 @ 20:51

robertmo wrote:I was writing about the internal limit in dosbox that is configured to never use 100% of your core to prevent stuttering.


And there is no limit when you set cycles' as concrete number manually.
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