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Comment Secure pairing is hard (Score 4, Interesting) 131

This is a general problem with devices that are "paired". How do you securely establish the initial connection, when neither side knows anything about the other?

The secure solutions involve some shared secret between the two devices. This requires a secure transmission path between the devices, such as typing in a generated key (like a WPA2 key) or physically carrying a crypto key carrier to each device (this is how serious cryptosystems work).

Semi-secure systems involve things like creating a short period of temporary vulnerability (as with Bluetooth pairing). There's a scheme for sharing between cellphones where you bump the phones together, and they both sense the deceleration at close to the same time.

Comment This is a job for QNX (Score 1) 161

Consider trying QNX, the message-passing real time OS, for this. This is a message passing problem, and Linux doesn't do message passing well. QNX has a scheduler optimized for message passing. You should be able to handle the UDP front end and fan-out without any problems. You can give the front-end process a higher priority than the other processes, which should let you get all the UDP packets into the fan-out program without losing any. That's what real-time OSs are for.

Trying to do anything high-performance with CPython's threads is hopeless. Watch this presentation on performance issues with Python's Global Interpreter Lock, Python has an internal scheduler, and it behaves very badly under load.

So each Python process should be single-thread. Have as many as you need, set up to get work via MsgReceive and reply by MsgReply. Don't set them up as "resource managers".

Python under QNX is being used by the robotics community, where real-time matters for some things, but not others.

QNX - great technology, marketing operation from hell.

Comment This belongs in the cluster manager (Score 4, Informative) 161

That level of control probably belongs at the cluster management level. We need to do less in the OS, not more. For big data centers, images are loaded into virtual machines, network switches are configured to create a software defined network, connections are made between storage servers and compute nodes, and then the job runs. None of this is managed at the single-machine OS level.

With some VM system like Xen managing the hardware on each machine, the client OS can be minimal. It doesn't need drivers, users, accounts, file systems, etc. If you're running in an Amazon AWS instance, at least 90% of Linux is just dead weight. Job management runs on some other machine that's managing the server farm.

Comment Tax advertising (Score 1) 418

There is a serious bipartisian proposal in Congress to reduce the tax deduction for advertising. Call your Congressional representative and tell them you support the elimination of tax deductions for advertising.

Because the US savings rate is so low (most people are spending almost all they earn), advertising does not increase demand. It just moves it around a bit. All advertising does is increase prices. There are many products, from movies to medications, where the advertising cost exceeds the cost of production. Let's put the brakes on advertising.

Comment Re:Evolution (Score 1) 253

I think it's more likely that more people are becoming obese because of exactly one factor: age. They are living artificially prolonged lifetimes due to access to adequate food and to medicine. It's easier to get fat when you are 50 than when you are 30 because of the natural changes in your metabolism.

Comment Re:Evolution (Score 1) 253

:-)

You make it sound like starving people are getting fat too.

If they are becoming obese, the particular individual has a surplus of caloric intake, if only for this year or month. This is not to say that they have proper nutrition. So I am not at all clear that the fact that there is obesity in the third world is confounding evidence.

Comment Evolution (Score 1) 253

For most of the existence of mankind and indeed all of mankind's progenitors, having too much food was a rare problem and being hungry all of the time was a fact of life. We are not necessarily well-evolved to handle it. So, no surprise that we eat to repletion and are still hungry. You don't really have any reason to look at it as an illness caused by anything other than too much food.

Comment Re: If you pay... (Score 2) 15

Martin,

The last time I had a professional video produced, I paid $5000 for a one-minute commercial, and those were rock-bottom prices from hungry people who wanted it for their own portfolio. I doubt I could get that today. $8000 for the entire conference is really volunteer work on Gary's part.

Someone's got to pay for it. One alternative would be to get a corporate sponsor and give them a keynote, which is what so many conferences do, but that would be abandoning our editorial independence. Having Gary fund his own operation through Kickstarter without burdening the conference is what we're doing. We're really lucky we could get that.

Comment Track-train dynamics (Score 5, Informative) 195

That jet-powered locomotive was neverintended as a useful means of propulsion. It was just to test track-train dynamics at higher speed. Not much was done with the info, since Amtrak wasn't into high speed rail.

The next big advances in high speed rail were Japan's Tokaido line and San Francisco's BART, both around 1970. The original Tokaido trains had conventional wheel arrangements, and required a very good and very high maintenance roadbed. The SF BART system had the first trains with an active suspension, with each car body supported on a triangle of three air bags controlled by electronic controls. This allowed a higher body height at higher speed, allowing more wheel travel and a softer suspension. Also, all wheels were powered, as is normal in transit operations.

The French TGV brought both of those ideas together - high speed plus active suspension with more suspension travel, with all wheels powered. This allowed high speed trains without excessive track wear. (That's a big problem with high speed rail. A French test in 1955 reached 331 km/h, but damaged the track seriously in only one run. There were serious doubts for years whether steel wheel on steel rail could ever go that fast in routine operation.)

As with cars, there's been more than enough power to go fast for decades. Wheel and suspension issues are what limit speed.

Comment Re:One hell of a slashvertisement! (Score 2) 15

I think TAPR's policy is that the presentations be freely redistributable, but I don't know what they and Gary have discussed. I am one of the speakers and have always made sure that my own talk would be freely redistributable. I wouldn't really want it to be modifiable except for translation and quotes, since it's a work of opinion. Nobody should get the right to modify the video in such a way as to make my opinion seem like it's anything other than what it is.

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