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Ever wonder what powers Google's world spirit sensing Zeitgeist service? No, it's not a homunculus of Georg Wilhelm Friedrich Hegel sitting in each browser. It's actually a stream processing (think streaming MapReduce on steroids) system called MillWheel, described in this very well written paper: MillWheel: Fault-Tolerant Stream Processing at Internet Scale. MillWheel isn't just used for Zeitgeist at Google, it's also used for streaming joins for a variety of Ads customers, generalized anomaly-detection service, and network switch and cluster health monitoring.

Abstract:

MillWheel is a framework for building low-latency data-processing applications that is widely used at Google. Users specify a directed computation graph and application code for individual nodes, and the system manages persistent state and the continuous flow of records, all within the envelope of the framework’s fault-tolerance guarantees.

 

This paper describes MillWheel’s programming model as well as its implementation. The case study of a continuous anomaly detector in use at Google serves to motivate how many of MillWheel’s features are used. MillWheel’s programming model provides a notion of logical time, making it simple to write time-based aggregations. MillWheel was designed from the outset with fault tolerance and scalability in mind. In practice, we find that MillWheel’s unique combination of scalability, fault tolerance, and a versatile programming model lends itself to a wide variety of problems at Google.

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Original author: 
Todd Hoff

It's not often you get so enthusiastic a recommendation for a paper as Sergio Bossa gives Memory Barriers: a Hardware View for Software Hackers: If you only want to read one piece about CPUs architecture, cache coherency and memory barriers, make it this one.

It is a clear and well written article. It even has a quiz. What's it about?

So what possessed CPU designers to cause them to inflict memory barriers on poor unsuspecting SMP software designers?

In short, because reordering memory references allows much better performance, and so memory barriers are needed to force ordering in things like synchronization primitives whose correct operation depends on ordered memory references.

Getting a more detailed answer to this question requires a good understanding of how CPU caches work, and especially what is required to make caches really work well. The following sections:

  1. present the structure of a cache,
  2. describe how cache-coherency protocols ensure that CPUs agree on the value of each location in memory, and, finally,
  3. outline how store buffers and invalidate queues help caches and cache-coherency protocols achieve high performance.

We will see that memory barriers are a necessary evil that is required to enable good performance and scalability, an evil that stems from the fact that CPUs are orders of magnitude faster than are both the interconnects between them and the memory they are attempting to access.

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Original author: 
timothy

Madwand writes "The NetBSD Project is pleased to announce NetBSD 6.1, the first feature update of the NetBSD 6 release branch. It represents a selected subset of fixes deemed important for security or stability reasons, as well as new features and enhancements. NetBSD is a free, fast, secure, and highly portable Unix-like Open Source operating system. It is available for a wide range of platforms, from large-scale servers and powerful desktop systems to handheld and embedded devices. Its clean design and advanced features make it excellent for use in both production and research environments, and the source code is freely available under a business-friendly license. NetBSD is developed and supported by a large and vibrant international community. Many applications are readily available through pkgsrc, the NetBSD Packages Collection."

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Original author: 
Peter Bright

AMD

AMD wants to talk about HSA, Heterogeneous Systems Architecture (HSA), its vision for the future of system architectures. To that end, it held a press conference last week to discuss what it's calling "heterogeneous Uniform Memory Access" (hUMA). The company outlined what it was doing, and why, both confirming and reaffirming the things it has been saying for the last couple of years.

The central HSA concept is that systems will have multiple different kinds of processors, connected together and operating as peers. The two main kinds of processors are conventional: versatile CPUs and the more specialized GPUs.

Modern GPUs have enormous parallel arithmetic power, especially floating point arithmetic, but are poorly-suited to single-threaded code with lots of branches. Modern CPUs are well-suited to single-threaded code with lots of branches, but less well-suited to massively parallel number crunching. Splitting workloads between a CPU and a GPU, using each for the workloads it's good at, has driven the development of general purpose GPU (GPGPU) software and development.

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Original author: 
samzenpus

hypnosec writes "Google has released the kernel source code of Google Glass publicly just a couple of days after the wearable gadget was rooted by Jay Freeman. Releasing the source code, Google has noted that the location is just temporary and it would be moving to a permanent location soon saying: 'This is unlikely to be the permanent home for the kernel source, it should be pushed into git next to all other android kernel source releases relatively soon'"

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Original author: 
Jon Brodkin


Ubuntu 13.04.

The stable release of Ubuntu 13.04 became available for download today, with Canonical promising performance and graphical improvements to help prepare the operating system for convergence across PCs, phones, and tablets.

"Performance on lightweight systems was a core focus for this cycle, as a prelude to Ubuntu’s release on a range of mobile form factors," Canonical said in an announcement today. "As a result 13.04 delivers significantly faster response times in casual use, and a reduced memory footprint that benefits all users."

Named "Raring Ringtail,"—the prelude to Saucy Salamander—Ubuntu 13.04 is the midway point in the OS' two-year development cycle. Ubuntu 12.04, the more stable, Long Term Support edition that is supported for five years, was released one year ago. Security updates are only promised for 9 months for interim releases like 13.04. Support windows for interim releases were recently cut from 18 months to 9 months to reduce the number of versions Ubuntu developers must support and let them focus on bigger and better things.

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Original author: 
Andrew Cunningham

Andrew Cunningham / Aurich Lawson

A desktop PC used to need a lot of different chips to make it work. You had the big parts: the CPU that executed most of your code and the GPU that rendered your pretty 3D graphics. But there were a lot of smaller bits too: a chip called the northbridge handled all communication between the CPU, GPU, and RAM, while the southbridge handled communication between the northbridge and other interfaces like USB or SATA. Separate controller chips for things like USB ports, Ethernet ports, and audio were also often required if this functionality wasn't already integrated into the southbridge itself.

As chip manufacturing processes have improved, it's now possible to cram more and more of these previously separate components into a single chip. This not only reduces system complexity, cost, and power consumption, but it also saves space, making it possible to fit a high-end computer from yesteryear into a smartphone that can fit in your pocket. It's these technological advancements that have given rise to the system-on-a-chip (SoC), one monolithic chip that's home to all of the major components that make these devices tick.

The fact that every one of these chips includes what is essentially an entire computer can make keeping track of an individual chip's features and performance quite time-consuming. To help you keep things straight, we've assembled this handy guide that will walk you through the basics of how an SoC is put together. It will also serve as a guide to most of the current (and future, where applicable) chips available from the big players making SoCs today: Apple, Qualcomm, Samsung, Nvidia, Texas Instruments, Intel, and AMD. There's simply too much to talk about to fit everything into one article of reasonable length, but if you've been wondering what makes a Snapdragon different from a Tegra, here's a start.

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Original author: 
Florence Ion

If you've ever needed a temporary phone number for whatever reason, there are several apps out there that you could turn to. Last summer, we wrote about Burner, an application on iOS that enables users to take on another phone number for a small fee. Unlike Google Voice or Skype, the app can assign your mobile phone a new number with just the touch of a button. Today, Burner has made its app available to Android users.



To make a burner phone number with the app, select the “Create Burner” button to choose an area code and then input the number the burner should forward to (it will automatically default to the number on your mobile phone). Unfortunately, you can’t use a land line as the callback number, because the number requires text message verification. You can then pick from a variety of burner options, with the most standard being the Mini Burner for $1.99, which offers a number valid for a week, 20 minutes, or 60 texts. After that, the number is effectively disposed of. There are also payment tiers: eight credits for $4.99, 15 for $7.99, or 25 for $11.99.

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At last year's RSA security conference, we ran into the Pwnie Plug. The company has just come out with a new take on the same basic idea of pen-testing devices based on commodity hardware. Reader puddingebola writes with an excerpt from Wired: "The folks at security tools company Pwnie Express have built a tablet that can bash the heck out of corporate networks. Called the Pwn Pad, it's a full-fledged hacking toolkit built atop Google's Android operating system. Some important hacking tools have already been ported to Android, but Pwnie Express says that they've added some new ones. Most importantly, this is the first time that they've been able to get popular wireless hacking tools like Aircrack-ng and Kismet to work on an Android device." Pwnie Express will be back at RSA and so will Slashdot, so there's a good chance we'll get a close-up look at the new device, which runs about $800.

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