Comment by fredmorcos | Hacker News Reader

Comment by fredmorcos | Hacker News Reader

Parent Full thread

> You admit that you don't have enough details to know exactly what they're referring to, yet you're confident enough to call their personal experience "obviously incorrect"?

I didn't admit to not having enough details. You have two tools:

1. Reasoning about the abstractions and implementations of how yes and /dev/zero work: the claims become obviously incorrect, even their own tests later in the thread show that on a "modern system".

2. Actually running the tests they claim (which would prove them correct): no freaking way to do that. Even they do not offer any numbers to back their own claims because everything in the argument is a maybe or a remember or a might or a may have.

> People's personal experiences can be interesting, and that adds to the conversation.

People claiming their personal experiences are fact without proving anything is hugely problematic. Remember that woman claiming her child got autism due to vaccines? Remember that US president claiming a child got autism due to vaccines?

I remember seeing the earth as flat when I was working as an astronaut on the ISS. Go check my "personal experiences".

I hope you see what I'm trying to convey here.

I really don't see how it's "obviously incorrect" when yes only needs to make system calls for writing, whereas /dev/zero needs to make system calls for both reading and writing. Furthermore you're assuming that both are highly optimized, whereas it's entirely conceivable that /dev/zero is less optimized.

If what you're trying to convey is that abstract reasoning based on fundamental principles without any consideration of real-world complications is a superior approach to determining what's true, well, I reject that.

> I really don't see how it's "obviously incorrect" when yes only needs to make system calls for writing, whereas /dev/zero needs to make system calls for both reading and writing. Furthermore you're assuming that both are highly optimized, whereas it's entirely conceivable that /dev/zero is less optimized.

When you're "only writing", there is a counterpart that needs to read, and you have to wait for that, same as /dev/zero. It's more conceivable /dev/zero is more optimized than yes: you know, because of how pipes and streams are an essential part of a UNIX or UNIX-like system.

> If what you're trying to convey is that abstract reasoning based on fundamental principles without any consideration of real-world complications is a superior approach to determining what's true, well, I reject that.

I agree with that. But the original comment only gives us few options to check for its validity, and some of those are not feasible.

1. Actually finding all those systems, version-specific, combinations of userspace tools, setting them up and running the tests on hardware that was at OP's hand "back then": Not feasible.

2. Reasoning abstractly would tell us quickly that the original comment is plain wrong.

3. Running the tests on a modern system (some default linux install or whatever) shows that (2) is even more probably correct.

Is it "more conceivable" or is it "obviously incorrect"? You switch freely between arguing that your conclusion is more probable and arguing that it's obviously correct.

I agree with you that your conclusion is more probable. But that's an entirely different thing. It is more probable that a Tesla P100D is faster than a Pinto. It is not obviously incorrect that one time a Pinto beat a Tesla, maybe because the Tesla was dragging a bunch of rocks and the Pinto was dropped off a cliff.

Make up your mind what your argument is: is the statement in question merely unlikely, or is it "obviously incorrect"? Once it is, make your argument without being a jackass.

I responded in the terms you were using, hoping that it would become clearer to you.

> It is not obviously incorrect that one time a Pinto beat a Tesla

Yes it is, because OP forgot to mention the Tesla was dragging a bunch of rocks and the Pinto was dropped off a cliff. So was I supposed to have the power to read OP's memories and go back in time to check whether they provided us with all the information we needed to check their claims? No, I worked with exactly what's in the comment.

So without catering to your language/terms you use: it is obviously incorrect. Even OP's own comment later in the thread (on a modern system though, mind you) shows that: https://news.ycombinator.com/item?id=14544002

You appear to be incapable of understanding any middle ground between "obviously incorrect" and "obviously correct." Is the concept of uncertainty that foreign to you?

Really? Because when it comes to something testable, like in this case either running a test of yes vs /dev/zero or looking at the source code of everything involved, there isn't any uncertainty that OP's statement is obviously incorrect.

The only uncertainty is OP's use of "back then", "from memory", "maybe", "could have", etc... without providing any evidence to support their statement.

They were talking about things in the distant past. (Distant in computer terms.) The only way there isn't uncertainty is if you tried all the systems that were available at the time in question.

The claim is testable, in theory. You didn't test it, nor did anyone else here, so the fact that it's testable doesn't remove any uncertainty.

> The claim is testable, in theory.

It's not feasible to test in any practical way.

You said it yourself:

> If what you're trying to convey is that abstract reasoning based on fundamental principles without any consideration of real-world complications is a superior approach to determining what's true, well, I reject that.

Enjoy :)

Other tests by other people show that /dev/zero is slower.

https://news.ycombinator.com/item?id=14544261

People are suggesting that it's because of the use of cat. So, if someone writes a program, and the only difference is between /dev/zero and yes, and one is slower than the other, it's fairly reasonable to make the assumption that /dev/zero is slower.

> People are suggesting that it's because of the use of cat.

It is:

    > cat /dev/zero | pv >/dev/null
    ^C97GiB 0:00:05 [1.79GiB/s]

    > < /dev/zero pv >/dev/null
    ^C.3GiB 0:00:06 [10.2GiB/s]

OP's own comment shows that /dev/zero is faster: https://news.ycombinator.com/item?id=14544002

Reply on news.ycombinator.com