Re: [hatari-devel] Hatari on constrained devices

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Le 16/01/2022 à 16:18, Christian Zietz a écrit :
Thomas Huth schrieb:

It's not measurable on modern CPUs.

I would agree to that.

Linux developers seem to look down on other platforms, because Linux has
the incredible "perf" tool. So, why not use it, I thought?

This is on a Raspberry Pi 400, certainly a less powerful CPU than in a
current PC. Somehow inspired by the command used during the EmuTOS
tests, I ran...

SDL_VIDEODRIVER=dummy SDL_AUDIODRIVER=dummy perf stat -e cycles -r 10
hatari --log-level fatal --sound off --fast-forward on --run-vbls 400
--fast-boot on --tos etos512de.img

... to measure the amount of ARM CPU cycles spent, without any video or
audio output overhead. These are the average values and standard
deviations for 10 repetitions ("-r 10") respectively:

  3,333,167,644      cycles   ( +-  0.45% )

  3,267,861,361      cycles   ( +-  0.53% )

Therefore, ENABLE_SMALL_MEM=1 even seems to be (very marginally) faster
in this test!


just on the method you used to measure speed difference , note that video output is not disabled, so you might get some video driver interfering with your test, adding some fixed delay, pause, sync or others. I would suggest to add "--disable-video 1" to really remove SDL's audio *and* video output, which will give a much better idea of what the emulation is really using , with as little SDL/OS interference as possible (also you can remove --fast-forward in that case and use the --benchmark option)

eg :

hatari --benchmark --sound off --disable-video 1 --run-vbls 8000 --fast-boot on --tos etos512de.img

Note that 400 VBL is a rather short time, ~8 sec of emulated machine, you might push it a little higher.

as for the result itself, I can't say if small mem makes any big differences.


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