Thursday, August 29, 2013

Stuff I'm reading, end-of-August edition

Already planning that Labor Day barbeque? Surely you'll need something to read, or at least some paper to provide the kindling when you stack up the briquets in your chimney starter...

  • It's finally here! 24 years after the Loma Prieta earthquake: 2013 Closure Fact Sheet
    This Labor Day weekend, the Bay Bridge will be closed to take the original East Span out of service and to open the new East Span to traffic. Work will be done at the Oakland Touchdown and the Yerba Buena Island Transition Structure to connect the new bridge to the existing Toll Plaza and Yerba Buena Island, respectively. Crews will also perform essential construction activities, including paving, striping and erecting barrier rail. Throughout the closure, maintenance will work on the West Span, replacing lighting fixtures, cleaning and painting the cable, and repairing finger joints.
    Meanwhile, Bay Bridge Celebration
    Due to the late notice regarding the opening, the planned public celebration has been postponed to a future date.
    Although, of course, it wasn't actually due to "late notice regarding the opening" at all.

  • Predator drone now part of battle against Rim Fire near Yosemite
    While unmanned aircraft have mapped past fires, use of the Predator will be the longest sustained mission by a drone in California to broadcast information to firefighters in real time.

    The plane, the size of a small Cessna, will remain over the burn zone for up to 22 hours at a time, allowing fire commanders to monitor fire activity, determine the fire's direction of movement, the extent of containment and confirm new fires ignited by lightning or flying embers.

    The drone is being flown by the 163rd Wing of the California National Guard at March Air Reserve Base in Riverside and is operating from Victorville Airport, both in Southern California. It generally flew over unpopulated areas on its 300-mile flight to the Rim Fire. Outside the fire area, it will be escorted by a manned aircraft.

    Officials were careful to point out the images are being used only to aid in the effort to contain the fire.

  • Nasdaq Blames a Surge of Data for Trading Halt
    the company highlighted more than 20 attempts by Arca, one of the exchanges run by NYSE Euronext to connect and then disconnect to the system that provides prices for recent trades in Nasdaq stocks. Those were accompanied by what Nasdaq described as a stream of quotes for inaccurate symbols from Arca, which Nasdaq’s system was forced to reject.
    As is often the case, Nanex has some much more interesting information about the incident: Nanex ~ 22-Aug-2013 ~ Quote Burst Loops
    A Theory

    ARCA's connection to the SIP breaks, so it retries, connects for a short period of time, which then breaks, another connection, which breaks, over and over in quick succession. Each connection reducing the total number of available connections (temporarily - for a few minutes), so that eventually any new connection fails. If Nasdaq is monitoring the health of the SIP via polling TCP, it won't be able to connect either (all connections are exhausted) and will think the SIP is down. But they probably see the SIP is still sending quotes from the outbound side (which, by the way, uses UDP/multicast). The engineers get the back-up SIP ready, but the back-up SIP doesn't know where the production SIP (the one not accepting connections) left off, because they can't connect to it either. The back-up SIP starts making requests to each of the 12 or so exchanges for the last 50 or so minutes of quotes (probably from the last known feed positions recorded before connections were exhausted).

    The back-up SIP request 50 minutes from EDGE, and transmits those, then requests and transmits 50 minutes from BATS, and so on. Sound familiar? It should, because that is exactly the pattern we see in the data.

  • Why don't DBMS's support ASSERTION
    So, why isn't ASSERTION supported by the vast majority of relational database packages? Is it soley a performance issue or is there something intrinsically hard about it?
  • Falsehoods Programmers Believe About Names
    So, as a public service, I’m going to list assumptions your systems probably make about names. All of these assumptions are wrong. Try to make less of them next time you write a system which touches names.
  • The Business of Protection
    You should know this about offensive line coaches: they are large, demanding men with Falstaffian appetites, jutting jaws, and no governors on their speech engines. They eat titanic portions. They cram their lips full of dip in film study like they are loading a mortar. They drink bottled water like parched camels, and in their leisure time would consider a suitcase of beer to be a personal carry-on item for them, and them alone. They are terrifyingly disciplined in the moment, and nap like large breed dogs when allowed.
  • The money is in the Bitcoin protocol
    Hopefully it is clear from the features of the Bitcoin protocol and system that crypto-currency is just one use case. Just as the BitTorrent protocol can be used in multiple ways for peer-to-peer data transfer, so can the Bitcoin protocol open up new and different possibilities.
  • How Moral Revolutions Happen (They Had A Nightmare)
    It’s hard to be egalitarian and admit that an inegalitarian impulse makes the moral world go round, in practice, always. (It’s easier for egalitarians to want equality, after all. They get to wear it as a badge of achievement. My believies!) Whatever equality we get is going to have to arise out of a process that seems to run contrary to that. That seems true.
  • You won't find this in your phone: A 4GHz 12-core Power8 for badass boxes
    Judging from the Power8, it looks like IBM is content to keep in the same clock speed range as the Power7+ chips - around 4GHz, give or take a little. It'll also move PCI-Express 3 controllers into the chip package to keep those hungry little Power8 cores fed; these controllers will offer a coherent memory protocol to external accelerators as well as a new cache hierarchy that goes all the way out to the L4 cache.

    As expected, IBM is also goosing the number of processor threads per core with Power8, doubling it up to eight per core. IBM has been vague about how many cores it might squeeze onto a die with the 22-nanometer shrink, and it could have probably done as many as sixteen cores if it had not added so much eDRAM L3 cache memory with the Power7+ and then boosted it even further with the Power8.

    On the workloads that Big Blue is targeting with its Power Systems iron, having more cache and cores running at near peak utilisation is more important than having lots of cores on a die. Just as is the case for mainframes, at the prices that IBM has to charge for Power Systems servers, the chip has to be architected to run at close to full-tilt-boogie in a sustained manner.

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