> If speed is an issue then you want it near the most commonly accessed data.
Yes. You expect the seek time to dominate performance.
The reason that the swap was faster when placed at the beginning is likely because the filesystem is mostly empty and so the allocated portion is at the beginning of the partition.
If the filesystem was near capacity and the files are distributed throughout, then you would expect the performance of the swap at the end and the swap at the beginning to start to converge.
Filesystem allocation patterns are relevant, one of the components of seek time is how far the heads have to seek. If most of the data is towards the front of the drive and your swap partition is towards the front of the drive, then the head will need to move less to get to the swap partition. If the data is towards the front and the partiton is near the end, then you would need to wait longer for the head to move, generally.
That's an interesting thought but unfortunately I'm travelling.
One thing is that the ocean is hardly blue. Not sure why my eyes register it as such, but it's mostly very close to black with nearly equal parts of red and green, at least the parts I sampled. I think a certain amount of this article's claim is predicated on the reader erroneously believing the ocean should become blurry.
The pilots aren't inventing anything on each flight. If they fly the airplane exactly the same way every time, that's a good thing. Writing new programs is not like that.
>> The pilots aren't inventing anything on each flight. If they fly the airplane exactly the same way every time, that's a good thing. Writing new programs is not like that.
I have an intern writing and app for internal use. He's using Python, tkinter, and one pip-install package for talking on modbus. Deployment to our hand full of users is easy. Low number of dependencies. It's going really well. A few days ago he said "I really would have liked to use ZZYXX-web-whatever for the GUI instead of tkinter". I said "you users don't give a fuck about that but keeping dependencies easy to manage is important". Users don't actually care about dependencies either, but they do care when it negatively affects getting the thing up and running (or slows development or...). His main gripe with tkinter was actually a lack of familiarity. I said "dude, a large part of your job is going to be learning. Get used to it."
Many architectural decisions in software are completely arbitrary and don't matter nearly as much as some people think. That's not to say all such decisions, but really a lot are not a big deal. In those cases KISS trumps most preferences and big ideas. IMHO of course.
Unfortunately, I think it's easier to fund something like the F-35 because it can be framed as a way to avoid an existential threat. It's difficult to do the same with fundamental science
That argument only holds because it was purported to replace different weapons systems that were needed for mitigating a threat. The threat is the primary motivation and cost reduction is secondary. I.e., if not but for the existential threat there's no need for the JSF or any system it would replace.
The F-22 was sufficient for threat mitigation. The F-35 raison d'être was cost reduction, after that was exportability which again was supposed to help with cost reduction.
Edit; comparing the logic of a 'but for' vs a 'necessary' condition. Was the F-35 necessary for threat mitigation. No. Was it framed as the necessary for cost savings, yes.
Your oversimplifying and missing a lot. The F-35 is not a replacement or substitute for the F-22.
The F-22 is an air superiority fighter. The F-35 is a multi role strike aircraft. The F-22 would never be allowed for export, because it has features we don't want to share even with allies. The F-35 was designed for export to allies from day one.
There's no scenario where just buying more F-22's made more sense than building the F-35. The F-35's project problems, primarily driven from the joint acquisition strategy are their own thing, completely independent of the F-22.
The F-35's problems as I understand it stem principally from the Navy wanting a VTOL craft. That whole system seems to be front and center when "stuff not working" comes up.
Marines not Navy, though they're a sub org of the Navy so a reasonable thing to say.
There's a Rand study on it. They concluded that the attempts at commonality didn't just fail, they proved counterproductive. They did a historical review of joint acquisition programs and found basically all of them hit the same flaw. As appealing as it may seem to congress, it's a bad strategy.
The F-35's problems as far as budget and schedule slippage were largely in the software section, and a lot of that goes back to structuring it as a single source cost plus contract. That incentivized LM to make the project as big and delayed as possible.
LM is infamous for this sort of thing. They turned Aegis into a clown circus of a billion different ship specific variants where they could charge N times to fix the same flaw in different nearly identical codebases. The Navy has been trying to extract themselves from it for like 2 decades now, with some signs of success finally showing up.
In short, LM is behaving in bad faith. This is unsurprising. They basically invented these tactics some decades back.
Back when Ash Carter was Sec Def, he called in LM and demanded they start hitting the promised numbers on marginal airframe costs. Reportedly the conversation went something like "do this or we'll curtail our buy" to which LM responded "by how much?" As replied "how about none?"
Suddenly they started hitting the numbers, surprise surprise.
We're about to have the same conversation about sustainment costs. I hope Austin drives as hard a bargain.
If you've read any of the limited info coming out about some of the AF's new projects like the B-21 or NGAD, it's pretty clear they took the lessons from the F-35 to heart and are using a very different approach, one where they hold the reigns of integration and can create competition at any time.
Their designed for slightly different roles. The F-35’s R&D looks hard to justify vs simply having more F-22, but the F-35B can do verticals takeoff for example and the F-22 can’t.
So, the real question is if the F-35’s should have had fewer versions and thus been more capable in it’s remaining roles.
There's similar analogies here to the space shuttle.
For the shuttle to get approved, it had to meet the demands of many masters. The fact that it had to meet DoD missions as well as NASA missions made it a bit of a boondoggle. Likewise, the JSF needed to meet the Marine Corps demands of VTOL to take the place of the AV8B.
It's hard to remain focused when you have so many stakeholders. As the saying goes, a camel is a horse designed by committee.
The space shuttle wasn't as bad as its reputation though. Both accidents had organizational causes and were entirely avoidable. And its huge payload bay and the fact it was a mobile base allowed for the construction of the ISS.
It just failed at reusability, it was more like refurbishability :) But many lessons have been learned from that.
I'm speaking more to the shuttle cost overruns, both in design and mission. I'd argue that the reusability aspect was central to the idea of a "shuttle" and if it failed at that, it missed its mark.
I agree 100% that there are organizational causes to past mishaps. As to whether or not it was avoidable...I tend to think they are rooted very much in human psychology and we think about risk. The same issues occur today within NASA (EVA 23 is a good example [1], despite the 'organizational' fixes put in place after Challenger and Columbia). Humans are really, really good at rationalizing the answer we emotionally want.
It has a thrust-to-weight ratio > 1, but it can't really take off vertically in the same sense as the AV8B or the JSF. The F22 still needs some appreciable runway so it's really a "short takeoff". I think the thrust vectoring maxes out around 25 degrees, where the JSF can be configured to 90 degrees.
>Was the F-35 necessary for threat mitigation. No. Was it framed as the necessary for cost savings, yes.
I think we're saying the same thing. The argument is, "Was the F22/F18/Fwhatever/weapon-system necessary for threat mitigation? Yes."
With that said, if proponents of the F35 want to frame it as "threat reduction + cost savings" that's how they get the budget approved. But the point stands that without a threat, there's no basis for the cost savings argument. I'm not saying it was effective as cost reduction.
To circle back to the original point, it's much easier to get a budget approved when the basis is existential threat, rather than "science is cool."
I don’t think it’s a great example of using existential threat for sales, when the whole thing was sold as a cost saving. Pretty much everyone at the time just wanted more F-22s. I was a technical advisor on the project.
>I don’t think it’s a great example of using existential threat for sales, when the whole thing was sold as a cost saving.
Again, if there is no threat (perceived or real), there is no need for a weapons system, period. Think of it this way, if there was a proposal for a cost savings for an anti-spacecraft/anti-asteroid system mounted to the JWST? I'm saying no, because there is no credible threat that would prevent. You need the threat first, in order for the cost savings of a program to have meaning if the basis of the program is threat mitigation.
>Pretty much everyone at the time just wanted more F-22s
Not really, unless you're only talking about a specific branch. Only the Air Force wanted F22s. As was stated by another commenter, the JSF was needed because it was because it fulfilled desires that other services had that the F22 does not provide.
Threat mitigation is largely nuclear shield; but if you’re taking about maintaining air superiority then the F-22 is where it is at. The Navy carrier fleets and Marines are force projection.
The JSF were sold around cost savings; half the price so you could buy twice as many.
I think you're taking a very narrow definition of what a threat means to make your point. To a Marine in Afghanistan, the threat was not mitigated by a nuclear arsenal. To them, close air support from a technologically inferior aircraft like the A10 did a better job of eliminating a threat than the F22 in many instances. To the original point, this is why it became difficult to retire the old plane despite the JSF and F22. It could be tied to a specific threat, and that meant it was politically much easier to defend keeping it around even if the business case was that it costs too much money. At the end of the day, politically defending a budget is much easier if it can be concretely tied to a credible risk.
It was canceled because the Navy said it wouldn't work, both because of cost and take-off weight of the proposed Naval variant relative to the capacity of then-current and in-development carriers.
Yes, if you prefer eye candy photos to public safety. By the way will James Webb wield a modern eye candy capable sensor? Not sure about that.
There is few worth from remote sensing unreachable (even in theory) objects. Kepler already proved theoretized Goldilocks Zone rocky planets and, in general, provided a lot of data for non-field research (less exciting than Hubble photos indeed). Last, but not least, what's the JWST's mission exactly?
Also, from taxpayers' money perspective Kepler's component quality was complete disaster.
So, I'd better invest in more Martian/Jovian probes than in revival of obsoleted project. Such revival is very similar to Russian GLONASS (a competitor to 1970s NAVSTAR) programme reboot.
The JWST's mission is to see deep infared, which can pass through interstellar clouds. It will uncover things that have been veiled to us since the beginning of history. It can only be built as a space telescope because the frequency of its intended observations are so low that to a device sensitive to them, air radiates light of blinding intensity.
There is a long list of scientists that know exactly what research they are doing on JWST down to the minute [0]
For example, Dr Christine Chen et al will be using JWST for at least 34.9 hours to study the Icy Kuiper Belts in Exoplanetary Systems using near infrared spectroscopy [1]
Yeah, I read that, just not impressed by minor projects with low outcome. It roughly equal to routine PhD-tier experiments done on the accelerator at some provincial lab.
Just look at breakthrough chances from, for example, 5 days trans-neptunian object search or the pointing of instrument at largely unexplored Uranus system for petty 30 hours.
I hate how shortsighted these comments tend to be, but I can understand them.
The money for projects like this, largely due to the sensitive nature of it all, still ends up staying local to the governments funding the projects, which means a significant minority of it still gets recouped in taxes two or three degrees down, and the balance that can't be recouped still ends up funding colossal technological advances, e.g advances in EM sensors, lensing, computing, electronic resiliency, power generation, the list goes on.
The reason governments spend on projects like this regardless of public opinion is because they're necessary to advance the state of science and engineeeing when investment returns are out of the question near-term.
Even defense spending operates this way, though the degree to which we pour good money after bad in defense is probably worth scrutiny. At least JWST will bring value, unlike the f35.
Well, all the tech advances brought by doing R&D of JWST happened already ~15 years ago and already are at the market. But its just the same thing as with R&D done for F-35. With notable exception F-35's R&D is still work in progress because of upgrades, while JWST will remain a piece of late 2000s tech to be taken out of the attic in early 2020.
Another important point to consider is that by having these big projects you maintain the ability to do them, capabilities need to be maintained by exercising them.
Kids who are taught less formal maths end up doing better at questions that have extra information to throw you off.
The distance from Boston to Portland by water is 120 miles. Three steamers leave Boston, simultaneously, for Portland. One makes the trip in 10 hours, one in 12, and one in 15. How long will it be before all 3 reach Portland?
So 15 hours. People who learn more plain arithmetic maths assume that the 120 miles and the fact that all the figures divide into it exactly must be significant, and try to do calculations when none are needed.
Thanks for your reply. I thought there was a point being made about education at a more meta level, since the piece was very old and it begs the question of why a really old essay is on hackernews.
Ask the person to implement "Hello world" and then count the lines of code, number of classes, inheritance depth, number of external dependencies, etc.
Yes, the man page is very good. The online gnu documentation is good, too. Some of the information will not be categorized as bash.[1] Also check out sed and awk.
They put a telegraph cable under the ocean in 1858. With all the technology (including materials) we have today, I bet it's very feasible from a technological point of view.
An economic point of view is a different question, though.
It's interesting to speculate on how it could be done. Maybe it could be soft, like a fire hose, and kept open by internal pressure. That way it could be unfurled from a ship. Rigid pipe seems pretty difficult.
O&G technology is pretty amazing. I guess you can develop some pretty amazing technology when you can invest many billions of dollars over many decades, because the payoff is huge. Makes you wonder where other technologies would be with that much expenditure.
