This author also has other things like: A compiler that emits only `mov` instructions and another compiler that deliberately messes with the control flow so that, if disassembled, common debuggers will draw symbols like skulls or threats. https://github.com/xoreaxeaxeax/repsych
inigyou 47 minutes ago [-]
He also bruteforced the entire opcode space to find undocumented instructions (sandsifter).
spoocecow 1 hours ago [-]
Oh wow, glad to see Chris Domas active online again!
michalsustr 1 hours ago [-]
Very cool! Also, huh interesting. I’ve used rdtsc to measure cycle diffs but had no idea its execution takes that long. Is that common across architectures?
7 minutes ago [-]
inigyou 54 minutes ago [-]
AFAIK it acts as some kind of execution barrier, to give meaningful timing.
what im seeing from this chart is that we should be using the nop instruction for everything
bee_rider 2 hours ago [-]
Well the best code is no code. Nop could be second best though.
inigyou 46 minutes ago [-]
Instructions unclear. Set the NX bit to ensure no code, and got a general protection fault.
IshKebab 17 minutes ago [-]
Using MMIO is cheating and makes the results very boring.
It would be much more interesting to know the results if you're only allowed to use main memory.
vardump 2 hours ago [-]
A great resource for any performance deoptimization.
metadat 2 hours ago [-]
It’s crazy how computers still seem to get perceivably slow every few years, given how many instructions can be executed in 1ms. Shameful, even..
What’s that law called about programmers wasting all the compute on abstraction?
mwigdahl 1 hours ago [-]
Wirth's Law I believe.
inigyou 45 minutes ago [-]
And remember to call him by name, not by value!
HappyPanacea 2 hours ago [-]
The new windows notepad is a disgrace
inigyou 46 minutes ago [-]
Andy and Bill's Law
summarybot 1 hours ago [-]
The OS should do less not more
LoganDark 2 hours ago [-]
Huh? A millisecond is an eternity!
57 minutes ago [-]
m463 1 hours ago [-]
I remember reading once somewhere:
If some app responds in 10ms or less, it is INTERACTIVE.
makes you think.
Xirdus 38 minutes ago [-]
It is literally impossible to respond to input in 10ms on most platforms, for various reasons. The USB input lag of 12-30ms and the 60Hz refresh rate of most monitors being just the first two.
arn3n 2 hours ago [-]
There’s definitely strategies here; A lot of the floating point operations use subnormals, and a lot of the worst instructions are slowed down by really, really fucking with MMIO.
achierius 2 hours ago [-]
It'd be really interesting to see whether the winning (losing?) instructions/strategies would be different on other architectures. At least right now the top spot (`fxrstor64` on MMIO, starve PCIe) seems relatively architecture-independent, but maybe something about MMIO ordering rules on e.g. POWER would be different enough to change that -- or perhaps open up new avenues?
I wonder what the actual limit on this `fxrstor64` is right now. If you can stall the PCIe bus for that long, then why not indefinitely? Certainly there's no forward progress guarantee here.
Score: 1 cycles Time: 0 nanoseconds
It would be much more interesting to know the results if you're only allowed to use main memory.
What’s that law called about programmers wasting all the compute on abstraction?
If some app responds in 10ms or less, it is INTERACTIVE.
makes you think.
I wonder what the actual limit on this `fxrstor64` is right now. If you can stall the PCIe bus for that long, then why not indefinitely? Certainly there's no forward progress guarantee here.