Please create an account to participate in the Slashdot moderation system


Forgot your password?

Comment Re:CPU cycle != 1 second (Score 1) 189

Not really.

A single "calculation" such as moving data between registers ("mov ax, cx") actually takes many clock cycles. The instruction has to be fetched and decoded, which may itself take several cycles. Then the instruction has to be scheduled, the operands have to be fetched from the register file, and eventually the result of the operation gets written back into the register file.

Thanks to pipelining, branch prediction, result forwarding, and so on, much of this latency can be hidden and, under ideal conditions, your processor might achieve an average throughput of many instructions per cycle because it is decoding and executing many instructions simultaneously. But, if you track any particular instruction from start to finish, it takes several cycles.

And of course, in practice there are much harder instructions than register moves. Division can take dozens of clock cycles. Waiting for data from main memory can take hundreds of core clocks. Mispredicting a branch stalls you out while you figure out where to start decoding from again...

Comment The problem with this poll... (Score 1) 224

By analogy: how much use would you get out of being able to drive your car at 1000 miles per hour?

My family lives almost exactly 1000 miles away, so once every few years I drive a thousand miles to visit them. So I suppose I'd get some use out of this, but of course I'm very reluctant to drive 1000 miles.

But the only reason I'm reluctant is because it (currently) sucks! It takes all day long and I have to plan it out. If I could make that drive in an hour, it would be so easy that I could just visit anytime, maybe every weekend.

It's silly to predict how much you'd use a connection like this based on what you're doing today, because your habits and the very marketplace of websites and services that you have to choose from is so very heavily influenced by the speeds that we currently have to put up with.

It's about how much you're not doing today that you could be doing, if you had a much, much faster connection.

Today's internet would be unusable if we had it ten years ago on dialup. Hopefully tomorrow's internet will be equally unusable on our current equipment.

Comment Re:Affirmative Action (Score 0) 397

We are in the 21st century. We need to get rid of diversity quotas. Let the most qualified person get the job. Bill Cosby is right in that Blacks need to rid themselves of the ghetto mentality and educate themselves. Blacks (everyone, really) need to take responsibility for their own situation instead of blaming it on events from the 1800s.

What have the 1800s to do with anything? Look back no further than the 1960s to find grossly horrible things like segregated schools and restrooms and so on. While the civil rights movement made many impressive accomplishments, instantly curing the land of inequality was not among them.

Even today in the 21st century, Blacks still seem to have a lot going against them. Their unemployment rates are far worse than those for whites. Law enforcement seems to be out to get them, e.g., look at prison demographics, drug sentencing disparities, stop and frisk, stand your ground laws, etc. The "ghetto mentality" as you put it---by which I infer you mean, e.g., absent fathers, gangs and guns, drugs, learning to be "street-smart", hiding your intelligence to avoid getting beaten up---is tragic, and seems to me to be both a symptom and a cause.

Many people would like to see a more diverse tech culture. There have been countless articles on Slashdot, for instance, about why there aren't more women in computing and whether that's bad and why that is and what can be done about it. I assume Mr. Jackson wants to have a similar discussion with these tech leaders. Maybe he has some ideas, or maybe it's a stunt to raise some money and publicity. Whatever the motive, it doesn't seem like an altogether bad thing to think a bit about what the tech industry could do to help out.

TFA says nothing about quotas.

Comment Re:Officials say? (Score 4, Insightful) 644

Damn straight you should count yourself lucky.

There are seriously terrible things out there. Cancer. Parkinson's. MS. But do go on. Complain about paying more than your share, you always-healthy person, with your great genes, with your great personal character and intelligence that have kept you away from drugs, cigarettes, alcohol, with your even temperament that has shielded you from depression. Complain, with your good job, where you aren't exposed to toxins, which pays for your good house in your nice neighborhood, where gang violence is the farthest thing from your mind, where you have a great grocery store that enables your fully organic diet, where you have a great gym just up the road that you work out at five days a week.

The whole point of insurance is that we all get screwed a little, so that when someone gets really fucking boned, they don't get screwed sideways on top of it. Even a perfect person like you can fall off a bike or get hit by a car.

Of course, you're also right. We're all getting screwed way more than we should because we didn't have balls to say to hell with wall street and insist on a single-payer system.

Comment Re:yes and no (Score 1) 337

Putting a gun in the locked cockpit seems basically reasonable. Maybe it could provide a last line of defense against terrorists who somehow manage to take over the cabin and pacify the passengers, and start working to bust down the door.

Giving guns to the cabin crew sounds like a terrible idea. Then, instead of having to try to sneak a weapon onto the plane (possibly getting caught, which could ruin any sort of 9/11 style simultaneous multi-plane conspiracy), the terrorists merely need to overpower a crew member to obtain a firearm.

If we're really worried about this sort of thing, well---the Air Force can have operators fly drones over Iraq from New Mexico. Can't we put some kind of emergency button in the cockpit that gives control of the plane to a remote operator, so if terrorists do storm the cockpit, the pilots can push the button to disable all local control of the plane?

Full disclosure: I don't own a firearm and don't really understand people who do.

Comment Re:Can we please stop reimplementing the wheel? (Score 1) 205

My excuse: web apps are way better to deploy than native apps, both for me and my users (computer engineers at my company).

  • My users don't even have to think about running an installer; they just click on the link in the email I send them.
  • When there's a bug, I just fix it and... behold, it's fixed! No bothering people to update, no worrying about old versions of the software doing something bad.
  • All that time we didn't waste on installation, upgrading, dll hell, testing installers, etc, can be spent doing actually productive work, instead.

Native software is fast, sure, but deployment sucks for everyone. How many times a day are you being pestered to update this or that, right when you're in the middle of trying to look up something for or check your email. It's like sitting down for dinner with your family after a long day, just to be called by a telemarketer.

Comment Re:A couple good options (Score 1) 338

Uh, no. I own neither iPhone nor iPad nor iPod nor iAnything else, and detest using my boss's button-less Apple mouse (which incidentally she has set up to scroll in an inverted way---just to fuck with me, I'm pretty sure).

My daughter was 2 (well, 23 months old, to be precise) when I set up her computer. I started her off with a typical, full-sized Microsoft laser mouse with two buttons and a scroll wheel. It was very confusing for her. I eventually ordered this mouse. It was a much better fit. FWIW, Amazon's reviewers overwhelmingly agree.

I'm sure she could handle a wheel-mouse now without trouble. But back then it made a big difference.

Comment Re:A couple good options (Score 2) 338

Mod parent up!

Qimo is great. It's a whole Linux distro geared toward young children, and includes Childsplay, GCompris, and TuxPaint.

I set it up an old P4 for my daughter when she turned 2. I remember sitting next to her and watching in awe as, over the course of 20 minutes of playing this "uncover the animal picture" game, she became proficient in using the mouse. Almost two years later, she is still playing very good, fun, appropriate, challenging games. She has always loved the painting program, which is really cool and has all kinds of fun things (e.g., draw with cats!). She opens programs by herself, chooses her own games, knows how to shut it down, etc.


  1. Get a one button mouse! You can find a small one geared towards a child's hand. It makes a world of difference when getting started to not have the confusion of two buttons and a scroll wheel.
  2. Get some cheap speakers for it, since the games (and even the painting program) have lots of sounds.

And of course, make computer time a together activity. Sit next to her, actively watching, encouraging, explaining, and participating.

Comment Re:oversimplified (Score 1) 403

so what that means is that *regardless* of the fact that CISC instructions are translated into RISC ones, the main part of the CPU has to run at a *much* faster clock rate than an equivalent RISC processor, just to keep up with decode rate.

I don't understand this reasoning.

If the backend can't keep up with the decode rate, say because

  • each CISC instruction is turning into a few RISC-equivalent micro-instructions, and
  • CISC instructions have an edge w.r.t. memory density, so you can keep more of them in the icache and have fewer stalls waiting for the next instruction to come from RAM.

Then aren't you winning?

  • You aren't stalled out trying to figure out what to do next.
  • Your execution units are busy doing productive work.
  • You can turn off the frontend fetch/decode stuff to save some power.

Obviously there has to be some balance. An anemic backend with an overpowered frontend will slow you down. But if the backend is reasonably powerful, it seems like you want to have it working as fast as it can, rather than idly waiting for the frontend to tell it what to do next.

Comment Re:Open source? (Score 1) 302


Whatever folks think is gained from open source here is a lie. Why? Like it or not, you have no way to verify the open source code is what the machine is running.

Using computers for voting is just a disaster, open source or not.

Scantron-style forms can be processed very quickly, can't be subverted en masse, and can be verified by actual people. Using anything else just reeks of corruption.

Slashdot Top Deals

Mathematics is the only science where one never knows what one is talking about nor whether what is said is true. -- Russell