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Comment: Re:Can't Go Backwards (Score 1) 736

by jsailor (#42882861) Attached to: Ask Slashdot: Why Is It So Hard To Make An Accurate Progress Bar?

You hit on the key with "Maybe a couple of numbers under it showing # files done out of # total files". I understand making a predictable progress bar is very difficult. What most people struggle with is knowing whether it's working or not. Using the file example, when downloading a disproportionately large file may stall the progress bar, but providing some indication that it is still receiving data provides the user with enough information to assume that the process is still working and not locked up.

Comment: Marketing from a start-up (Score 3, Informative) 271

by jsailor (#34783750) Attached to: Hackers Find New Way To Cheat On Wall Street

There are several products on the market that are employed by the Exchanges and their large customers to track all of this.
This is a marketing paper for what appears to be an interesting product.
Existing vendors already capture, log, analyze (in realtime), traffic across multiple probes and provide real-time alerting along with monitoring, measurement, etc. These products are all leading edge and are changing rapidly. They've solved many problems with proprietary schemes of various sorts. Not the least of which was time synchronization at the nanosecond level.

For very simple public information, just look at latencystats.com. Keep in mind, more detailed info and analysis is going on behind the scenes.

Image

Underwear Invention Protects Privacy At Airport 325

Posted by samzenpus
from the protecting-the-goods dept.
Thanks to Jeff Buske you don't have to be embarrassed while going through the full body scanners at the airport. Buske has invented radiation shielding underwear for the shy traveler. From the article: "Jeff Buske says his invention uses a powdered metal that protects people's privacy when undergoing medical or security screenings. Buske of Las Vegas, Nev.-Rocky Flats Gear says the underwear's inserts are thin and conform to the body's contours, making it difficult to hide anything beneath them. The mix of tungsten and other metals do not set off metal detectors."

Comment: Re:Linux: 1, MS: -1 (Score 1) 452

by jsailor (#34012462) Attached to: LSE Breaks World Record In Trade Speed With Linux

While I can't speak to any specific exchange directly, I can say that their designs are fairly similar and fairly simple.
Fast links provide low serialization delay (the time required to put bits on the wire). A 512 byte packet requires 4.256 microsec at 1 Gbps and .4256 microsecond at 10 Gbps (40 or 100 Gbps are not linear jumps)
Fast switches forward and sometimes filter traffic. the faster equipment requires between .7 and 6 microseconds to begin spitting out packets. think about systems that start forwarding traffic prior to the entire packet being received. These are Ethernet values. Infiniband switch can be 2+ times faster.
The network design is very simple. Not your traditional vendor-derived three tier architectures, but 1, 1.5, or 2 tier architectures. The largest variations are in the handling on security and market data distribution. Firewalls are slow and typically deprecated. Market data is a religious decision marred by questionable technology implementations
Utilization is typically below 1% for any reasonable measurement period. Bursts may push an interface to line rate fractions of a second. Keep in mind that 10 GigE can carry 14.8 Mpps - so these bursts stress switch buffers and the receiving systems.
The total network latency within an exchange's network is well below 100 microseconds with some offering delays below 50 microseconds and a 1 or 2 that are below 30 microseconds.
The largest contributor to delay is, and will be for some time, the matching engines and other hosts that process the trades.

Education

Best OSS CFD Package For High School Physics? 105

Posted by timothy
from the why-not-stop-at-algebra-I? dept.
RobHart writes "I am teaching a 'physics of flight' unit to grade 11 Physics students. Part of the unit will have the students running tests on several aerofoils in a wind tunnel. I also want to expose them to a Computational Fluid Dynamics package which will allow them to contrast experimental results with those produced by the CFD package. There are a number of open source CFDs available (Windows- or Linux-based are both fine), but I don't have much time to evaluate which are the simplest to use in terms of setting up the mesh, initial conditions, etc. — a very important issue as students do not have much time in this unit." Can anyone offer insight about ease of use for programs in this niche?
Education

Recommendations For C++/OpenGL Linux Tutorials? 117

Posted by timothy
from the no-you-guide-me dept.
QuaveringGrape writes "After a few years of Python I've recently been trying to expand my programming knowledge into the realm of compiled languages. I started with C, then switched over to C++. A friend and longtime OpenGL programmer told me about NeHe's tutorials as a good step after the command-line programs started to get old, but there's a problem: all the tutorials are very Windows-based, and I've been using Linux as my single platform for a while now. I'm looking for suggestions for tutorials that are easy to learn, without being dumbed down or geared towards non-programmers."
Biotech

Monitor Your Health 24x7 With the WIN Human Recorder 66

Posted by timothy
from the paranoia-count-high dept.
kkleiner writes "Japanese venture firm WIN Human Recorder Ltd is set to bring a health monitor patch to market that is capable of keeping tabs on all your vitals. The HRS-I is a small (30mm x 30mm x 5mm) lightweight (7g) device that adheres to your chest and relays the data it collects to a computer or mobile phone via wireless connection. While the HRS-I only directly monitors electrocardiograph information, body surface temperature, and movement (via accelerometers), it can connect to sensors for heart rate, brain waves, respiration and many other important health indicators. WIN is selling the HRS-I for around ¥30,000 (~$330) and providing monitoring software for around ¥10,000 (~$110)."

Apple Orders 10 Million Tablets? 221

Posted by ScuttleMonkey
from the pricepoint-better-be-right dept.
Arvisp writes "According to a blog post by former Google China president Kai-Fu Lee, Apple plans to produce nearly 10 million tablets in the still-unannounced product's first year. If Lee's blog post is to be believed, Apple plans to sell nearly twice as many tablets as it did iPhones in the product's first year."

Comment: Re:Could be worse (Score 1) 164

by jsailor (#30550768) Attached to: Testing Network Changes When No Test Labs Exist?

I think the point is that Willie Mays and Joe DiMaggio would both get the job done, but do it in different ways. Willie Mays would make the catches while running, diving, over-his-head, etc. All of which looked amazing and made the highlight reels. DiMaggio, did a better job of preparing and positioned himself better so that when catching a similar hit, he would be in position to catch the ball standing up. Both were great athletes, but DiMaggio made the job look routine. Even though he was equally capable of making the fantastic plays, his approach was more safe because he didn't have to make them so often. Planning and design vs. fire fighting.

Comment: Re:Incompetent developers require more servers (Score 1) 752

by jsailor (#30513160) Attached to: The Environmental Impact of PHP Compared To C++ On Facebook

Using real world data from real environments...

the cost of running a server is $3,000-$6,000 / year. The wide variation is due to differing data center resiliency profiles and utility costs (power, water).
That figure includes data center costs (space, power, cooling, utility, etc.) and excludes server operations staff, depreciation of hardware, support systems, backup systems, network, etc.

Firms that understand this and bill back the business units appropriately have markedly different environments.

Comment: Latency and Speed (Score 1) 624

by jsailor (#28807749) Attached to: Stock Market Manipulation By Millisecond Trading

Short answer: Transmission speed impacts latency when you consider how long it takes to drop all the bits (one at a time) onto the wire. This has not typically been a concern with LANs, but as latency gets measure in 10's of microseconds, it is a very real concern.

Long answer:
Network speed is a bottleneck in that it impacts latency through serialization delay (the time it takes to drop the bits onto the wire). This sounds trivial when were talking about Gigabit, 10 Gigabit and 100 Gigabit speeds, but the Exchanges are striving to meet network and trading latencies measured in microseconds. You can do the math yourself to see how long it takes to drop 512 bytes (1 bit after another) onto a wire. If you're anal you can add the appropriate overhead for framing, headers, etc.
Switching latencies also vary significantly and have a tremendous impact on vendor/product selection. This also drives network architecture as eliminating as many switching hops as possible is key maintaining latency budgets.
Distance from the exchanges is important, but not as important as switching latency and serialization delay. You can do the math to figure out how much time it takes bits traveling at roughly 2/3 the speed of light to reach their destination. Most trading firms pay large premiums to either collocate at the exchanges or very, very close to them. So-called program trading is performed by autonomous server farms operating in these spaces.

I can go on, but refer back to the short answer. Network speed is important.

Comment: Re:Seriously (Score 1) 302

by jsailor (#27596437) Attached to: NYC Wants Ideas For "Taxi Technology 2.0"

This worked really well for the banking industry...

Also, perhaps you're too young to remember how bad the taxi experience used to be before tighter regulations were developed AND enforced.
Despite the comments from people that don't live or work in NYC, cabs here are infinitely cleaner, better kept, and safer than cabs in other cities. NYC cabs are limited to 3 years of operation. Cab companies in other cities (Philly, Chicago, etc.) buy these 3 years olds and proceed to drive them into the ground. If you look closely you can usually see a spot or two of NYC yellow where the new paint has chipped off. NYC cabs have mandatory A/C for the passenger section and there's a simple number to call if you're having problems with the cab (311). There is a fixed rate from the JFK to Manhattan. All of this, including the rider's "bill of rights" is displayed clearly inside the cab. As is the driver's license number in case you want to report an issue.
If you're willing to give that up, so that you can save a few dollars and put up with low quality experience that results from cost savings and weak enforcement - please do so in whatever second tier city you inhabit. Finally, NYC cabs are already significantly cheaper than cabs in any other city.

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