glangdale · HackerTrans

в прошлом годуdiscuss

I'm not sure what you mean here. A single cache line is 64B, and this table would thus occupy 4 cache lines, but typical x86 cache sizes are 32K or for more recent cores 48K. Whether consuming 1/512th or 1/768th of your level 1 cache is excessive is a value judgement, but most people wouldn't think so.

glangdale

в прошлом годуdiscuss

Yes, that's it. Vectorized SIMD annihilates this problem, a space I've been working in since 2006 and it wasn't all that new even then. A close second would be a heavily optimized (pipelined and less branchy) table or bitvector lookup. Doing anything that involves lots of control flow, like the grandparent post, will be slow as a wet week with our without bit manipulation tricks due to the inherently unpredictable nature of the branches (subject to our input).

glangdale

в прошлом годуdiscuss

To paraphrase Arthur Dent, "this must be a strange new usage of the word 'fastest' with which I am not previously familiar".

The fastest way to detect a vowel in a string on any reasonable architecture (Intel or AMD equipped with SIMD of some kind) is using 3-4 instructions which will process 16/32/64 (depends on SIMD length) bytes at once. Obviously access to these will require using a Python library that exposes SIMD.

Leaving SIMD aside, a flat byte array of size 256 will outperform a bitmap since it's always faster to look up bytes in an array than bits in a bitmap, and the size is trivial.

glangdale

5 лет назадdiscuss

I feel you are focusing on the literal aspect of what I wrote and ignoring the broader implications. The tradeoff here between "student OS kernel principles" and "grind through a USB driver implementation" will recur as you try to add drivers and hardware to run meaningful-to-users workloads.

So you wind up with a research operating system that has finger-painting graphics, can't talk to modern SSDs or networks cards... or you somehow conjure up the resources to build an enormous number of drivers.

If you "hack Linux or a bsd" - or even more timidly - use ebpf - the constraints of what you build are going to result in you basically building "more UNIX stuff". This isn't bad research, but the sheer mass of constraints you're taking on if you accept all the design tradeoffs of Linux/bsd/eBPF/whatever means you're certainly not doing the sort of OS research that the original author talked about.

glangdale

5 лет назадdiscuss

No. Driver work is painful but it mostly teaches you about the h/w in question; you don't learn deep principles from a lot of it. You just grind away, spec in hand, until stuff works. A lot of this winds up being "one damn thing after another". There's a good deal of craft to it, and I don't mean to deprecate it, but it's not broadly applicable.

Conversely, the work they did in kernels has a huge amount of transfer to thinking about concurrency, which is truly valuable - and deep. It also meant that they acquired a far less magical idea of where things like processes and threads come from, having actually built the mechanisms to make them happen (you build a thread library in a warm-up project).

As for microkernels - they often punt a lot of the hard concurrency stuff up to user space servers, which will wind up needing exactly the kind of concurrency that the students learned to build.

glangdale

5 лет назадdiscuss

It was a fantastic experience, although TA'ing it was daunting. Like the apocryphal Ledru-Rollin quote: "There go the people. I must follow them, for I am their leader", it was frankly hard to keep up with all the different approaches students conjured up.

I believe that the course number changed at some point - or some shallow aspect of the course was set to change - and a bunch of industry people called the university to express concern. It is/was (I can't speak for the current iteration of the course, although I have no indication that quality has slipper or anything) truly transformative.

I offered to run a 'franchise' of the course at the University of Sydney a while back and was informed that anything quite that transformative wasn't really an option; our job was at least in part to pass engineering students who didn't care that much about computing.

glangdale

5 лет назадdiscuss

A perennial complaint; Rob Pike had a trollier but similar version years back. I'm not nearly as optimistic that we have the resources to cope with the monstrous complexity of hardware now.

An anecdote I like to share is that while I was TA'ing CMU's 15-410 operating systems course (a great course - build a preemptive multitasking operating system from scratch) was that the student projects could run on real - if old - hardware. There was a PC that could boot your stuff if you put it on a disk.

This PC had to have PS/2 interface to the keyboard, though. A newer PC would be all USB. Apparently, the complexity of the codebase to talk to the USB device was around the similar level of complexity to the entire preemptive multitasking operating system the students were building (and, of course, considerably less educational). I mean, this wasn't a full-functioned OS, but it allowed multitasking and preemption of kernel calls, so seriously non-trivial.

Multiply this story by all the devices a reasonable OS would be expected to talk to and it's a scary prospect for the OS researcher... and if you don't have those devices up and running, good luck supporting most workloads anyone cares about.

glangdale

7 лет назадdiscuss

OK, so you're still going, too. Neat.

The analogy to India and China is pretty good, aside from a few tiny differences, like the fact that most single males in the valley we're talking about intentionally came there from somewhere else, are hugely wealthy relative to poor Chinese and Indian workers, and that it's ever so slightly easier to cross a county line to somewhere less bizarre than Santa Clara than it is to emigrate out of India or China.

It's funny how I can post a ranty-but-true thing about how the world actually works (i.e. "having some table stakes attributes will not make you a 'pussy magnet'") and just get bombarded by people like you complaining about the dreaded ratio and philosopher1234 who clearly is wondering whether his girlfriend is about to leave him for a rock-climbing jazz musician who doesn't bathe or something.

All these dudes come flooding into an area to work in a dude-dominated industry and collect Big Valley Salaries and somehow this is a problem that needs to be worked out? If it's that big a problem, leave. Geez. How hard it that to figure out?

glangdale

7 лет назадdiscuss

OK, once more: at no point did I ever suggest that people can't find love if they don't have much more than table stakes things like "clean fingernails" and "stable jobs" and "capability for love", only that they should not feel entitled to attention from the appropriate gender.

I'm curious as to what's driving your serial misinterpretation, if anything. I suppose it's possible you're just having difficulty with parsing out arguments and reasoning about them (is English your first language?), but it seems just as likely you're on the insecure side. You keep cropping up and asking complete strangers on the Internet to validate your relationship.

So, ok. Dude, you're probably fine. Although it's not a guarantee; there's still a possibility that your girlfriend runs off with Mick Jagger, or a rock-climber who works in a cafe who has $18.23 in his bank account, or a temperamental chess player with a huge schlong who bathes once a month, whether he needs to or not. Keep your eyes peeled at all times!

glangdale

7 лет назадdiscuss

Hacker News is full of advice for people attempting to get successful outcomes in situations where there are 20,000 applicants to 100 jobs, so I'm amazed that a discussion of how you can improve your outcomes under a 150:100 ratio is now "victim blaming".

Also, newsflash: not getting attention from the gender(s) of your choice doesn't make you a "victim". We're back to the entitlement thing, I guess.

But yes, moving out of the Bay Area will help. However, I'd hazard a guess that unless someone moves to somewhere where a six-figure salary makes them a minor princeling, your problems may follow them. Because a boring dude in SF or the Bay is still a boring guy in Des Moines or Scranton.

glangdale

7 лет назадdiscuss

You're saying that "if someone tells you some entitled garbage, and you believe it, it's not entitled garbage?". So essentially it's not entitlement because someone else told you?

glangdale

7 лет назадdiscuss

It's weird you keep cropping up on this thread interpreting me saying "women are not going to flock to you just because you meet some basic criteria so it is foolish to start behaving that you are entitled to this" as "obviously, philosopher1234 cannot possibly have a girlfriend, q.e.d".

glangdale

7 лет назадdiscuss

Well, first of all, lose that sense of entitlement. It's hard to think of much that's less appealing than petulance.

It's also a pretty great way to blind yourself to what 'league' you're actually in. A number of my tech friends have wasted an extraordinary amount of time chasing women absurdly out of their league because they've been convinced that "having a decent job", "being well-spoken" and "eating with their mouths closed" somehow puts them in the top 3% of desirable men. Really, no.

Second, go have a life. You know, other activities outside work? Socializing? This is important anyhow. Preferably do activities because you're interested in them and socialize with people you like, not because you're there to "pick up chicks". Nothing is more tiring than dudes relentlessly on the make in every situation.

This isn't guaranteed to work... especially with dire male/female ratios (although not living like a schlub probably evens the odds a bit). And plenty of people are just really unattractive, uncharismatic, whatever. Not sure what to do then.

glangdale

7 лет назадdiscuss

This is a strange response, mostly a wilful misreading of what I wrote. But yes, having your "life in order" isn't actually all that shit-hot, and yes, "expecting to be able to date" if you're not very interesting is actually "too much entitlement".

Because last time I checked, "expecting to be able to date" involves the decisions of other people and you're not really generally entitled for other people to do much more than treat you with decency and respect. Not, necessarily, want to jump your bones. Sorry.

glangdale

7 лет назадdiscuss

Username checks out. Did you have a point, or are you just here to offer content-free snark?

glangdale

7 лет назадdiscuss

I like how a guy earning a fairly unremarkable-when-we-adjust-for-cost-of-living salary with a bunch of fairly unimpressive table-stakes credentials: "clean cut, well-spoken, hard working, respectful" (whaddaya want? a cookie?) is meant to be a Amazing Pussy Magnet.

One of the major factors - aside from the gender ratio - behind tech guys not finding partners is this weird expectation that if they shave, clip their fingernails, and don't act like an outright dirtbag that women will flock to them, regardless of whether they have any personal appeal or not.

A lot of dudes in tech are just bores with zero interests and a outsized sense of entitlement to the opposite sex (talking about the het guys, don't know how it works on the other side of the fence). Just to top it off, they expect to be magnets to interesting women, too - these guys are the first to sneer at gold-digging women who are, frankly, their appropriate mirror image. That is, if the only thing you can say about yourself that isn't table-stages normal person stuff is that you're "a SWE making $120K+ a year" who exactly do you think you're going to attract?

Bonus points: deciding that the one thing that's missing from the above picture is being swole, and filling in any extra time not spend being a "respectful male SWE" with incessant iron pumping.

glangdale

7 лет назадdiscuss

Absolutely. I was trying to figure out something to do with timeouts in an SMT solver called Yices, so I had search strings about signals and alarm and Yices - of course. Google decided that this was a generalized programming question and displayed a lot of stuff about signals and alarm handling that didn't relate to Yices.

How likely a search time is "Yices", ffs? Feels like something that exotic ("statistically unlikely") probably is meant to be in the results by default.

glangdale

7 лет назадdiscuss

I agree, and contrary to the two other responses, I can't separate the toxic emotion stuff from the supposed neutral argument underneath it. Why? Well, I have only vague memories of Hypercard (played with it as a kid), so when you read the arguments about it from someone who clearly knows a lot more, you're expected to take it on authority.

However, if that person is ranting and raving and calling people who disagree with him "autistic", it's impossible not to suspect that the guy has the 'thumb on the scale' even in the portion of the discussion that's apparently neutral. As someone pointed out in his comment section, he was just plain making stuff up about Jobs killing Hypercard (despite his attempts to back-and-fill on the issue).

glangdale

7 лет назадdiscuss

Airports are never going to be high on the list of places sans billboards and are usually privatized space. I'm not too bummed out about airports and shopping centers, but I draw the line at public transit and actual fully public spaces like the streets of downtowns (which are choked in ads in Sydney now).

glangdale

7 лет назадdiscuss

Correct. It's awful here in Sydney. The local government a long time ago decided that it couldn't be bothered to put up and maintain infrastructure like bus shelters and the like, so they got JC Decaux to do it (a French company, whose maintenance trucks amusingly use an Australian flag as their major design motif) in exchange for plastering the whole city with ads.

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