2024/11/01

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2024-11-01 21:27:47 +0100 <zzz> monochrom: 8GB Ram :)
2024-11-01 21:26:57 +0100 <monochrom> OK I'll stop until I think up a better joke!
2024-11-01 21:26:18 +0100 <monochrom> What if the web browser already eats up 0.4999GB and the OS eats up the rest :)
2024-11-01 21:25:47 +0100 <zzz> tomsmeding: i don't understand why in your test the difference between deepseq and rnf disappears
2024-11-01 21:25:10 +0100 <tomsmeding> case 1 and 2 run lean
2024-11-01 21:25:06 +0100 <tomsmeding> monochrom: that would be for case 3 only
2024-11-01 21:24:54 +0100 <EvanR> intel celery
2024-11-01 21:24:48 +0100 <monochrom> OK now I'm hoping "oh it only has 0.5GB RAM so yeah it's thrashing"
2024-11-01 21:24:26 +0100 <tomsmeding> but yeah with a CPU of that class I would not expect a 7x difference, but I guess it could be
2024-11-01 21:24:20 +0100 <zzz> 4 cores
2024-11-01 21:24:12 +0100 <zzz> plugged in, not sure if it's throttling
2024-11-01 21:23:38 +0100 <tomsmeding> that can still mean various CPUs it seems
2024-11-01 21:23:36 +0100 <EvanR> "did you check if it's plugged in"
2024-11-01 21:22:54 +0100 <zzz> HP ProBook 440 G4
2024-11-01 21:22:23 +0100 <zzz> tomsmeding: not sure, it's not mine. sec
2024-11-01 21:21:52 +0100 <monochrom> I was hoping "brand new laptop using the brand new intel lake cpus so yeah it's a well-known regression" >:)\
2024-11-01 21:21:36 +0100 <tomsmeding> O.o
2024-11-01 21:21:24 +0100 <dolio> I was helping someone out a week or so ago, and they were doing something on their laptop, and my 10 year old desktop might have been that much faster when I tried it.
2024-11-01 21:21:18 +0100 <tomsmeding> what model number?
2024-11-01 21:21:08 +0100 <zzz> tomsmeding: old hp laptop, core i5 7th gen
2024-11-01 21:20:45 +0100 <tomsmeding> zzz: if it's a laptop, are you sure it's not throttling? Is the power cable attached? If it's intel, is turbo boost enabled and does the cpu reach similar frequencies for both tests?
2024-11-01 21:20:19 +0100 <dolio> I don't know about that.
2024-11-01 21:20:03 +0100 <tomsmeding> my CPU is like 7x as fast as yours? That feels unlikely
2024-11-01 21:19:44 +0100 <tomsmeding> okay so they are at least the same but 1. why are they slower than your code, and 2. what CPU is that, I know mine is fairly fast but _this_ fast?
2024-11-01 21:19:09 +0100 <zzz> Range (min … max): 4.137 s … 4.276 s 10 runs
2024-11-01 21:19:06 +0100 <zzz> Time (mean ± σ): 4.208 s ± 0.048 s [User: 4.195 s, System: 0.006 s]
2024-11-01 21:19:04 +0100 <zzz> Benchmark 2: ./hs/test 2
2024-11-01 21:18:59 +0100 <zzz> Range (min … max): 4.106 s … 4.249 s 10 runs
2024-11-01 21:18:56 +0100 <zzz> Time (mean ± σ): 4.171 s ± 0.038 s [User: 4.115 s, System: 0.051 s]
2024-11-01 21:18:56 +0100 <zzz> Benchmark 1: ./hs/test 1
2024-11-01 21:18:41 +0100 <zzz> tomsmeding:
2024-11-01 21:17:35 +0100 <haskellbridge> <zwro> "the problem with common sense is that it's not common at all" — someone
2024-11-01 21:16:46 +0100 <monochrom> Stepping back a step, people even hold opposite opinions on whether you should let GHC optimize or you should distrust GHC and optimize by hand.
2024-11-01 21:15:30 +0100 <monochrom> GHC out-smarts common sense in some cases and defies common senses in some others. Also people hold opposite "common" senses.
2024-11-01 21:13:46 +0100 <dolio> evaluate returns the value it evaluates, too.
2024-11-01 21:13:38 +0100 <EvanR> like scanl with tuples
2024-11-01 21:13:34 +0100 <tomsmeding> we're talking maximum residency of 2 GB and productivity of <25%, versus maximum residency of 40KB and productivity >99%
2024-11-01 21:13:27 +0100 <EvanR> it's a situation like this that I half expect ghc to pull some kind of magic and be efficient regardless of common sense
2024-11-01 21:12:56 +0100 <tomsmeding> monochrom: and if it really doesn't matter, then how do you explain 'evaluate (force x) >> pure ()' taking more than 4x as long as 'evaluate (rnf x)' and thrashing the GC meanwhile? :p
2024-11-01 21:12:25 +0100 <monochrom> OK OK this one is "... seq x" so yeah you're right.
2024-11-01 21:12:11 +0100 <EvanR> foo and bar are the same object in this case
2024-11-01 21:11:59 +0100 <tomsmeding> mind that this is evaluate, hence seq#, not seq -- not sure if that matters
2024-11-01 21:11:56 +0100 <monochrom> "foo seq bar" returns a pointer to bar but not foo.
2024-11-01 21:11:44 +0100 <EvanR> yes it's cheap but you can't have discarded the entire thing prior to the simple check
2024-11-01 21:11:34 +0100 <tomsmeding> monochrom: sure, but does not keep a reference to the value?
2024-11-01 21:11:12 +0100 <monochrom> Nah the extra seq is at worst just an extra check "oh this is already a value, moving on".
2024-11-01 21:11:00 +0100 <tomsmeding> zzz: can you reproduce the difference between 1 and 2 with my code?
2024-11-01 21:10:48 +0100 <tomsmeding> zzz: that's version 3 explained
2024-11-01 21:10:38 +0100 <tomsmeding> hence the memory use
2024-11-01 21:10:34 +0100 <tomsmeding> that's... a fair point: you have to hold on to the root of the data structure to WHNF it