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Comment Re:Lots of moving parts (Score 1) 449

Some things we just can't segregate, such as the name cache. Shared locks only modestly improve performance but it's still a whole lot better than what you get with an exclusive lock.

What is the challenge with the namecache, specifically? If its due to being LRU then there are approaches to mitigate the lock. A buffering approach like this Java cache batch updates to avoid lock contention. Another technique is to take a random sample to be probabilistically LRU, like Redis does.


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Link to Original Source

Comment Re:Umm? (Score 1) 250

As a nit, many algorithms that seem fundamentally linear can, in fact, be parallelized. A classic stack (last-in, first-out) seems strict since there is a single point of contention (the top of the stack). However, using an elimination technique allows entries to be transfered between the consumer and producer without updating the stack and thereby supporting concurrent exchanges. Similarly a tree is often used for maintaining sorted order (e.g. red-black) but concurrent alternatives like skip-lists provide similar characteristics. Another low-level example is an LRU cache where every access mutates the eviction order can be made concurrent by using an eventual consistency model to delay updates until required (e.g. writes). As these algorithms are worked out by experts who resolve their bugs prior, often times consumers of the libraries just need to use them with some cases needing to be aware of what can be done safely/atomically.

At an application-level, while many problems cannot be parallelized, Gustafson's Law provides an answer to Amdahl's dilemma. While the speed-up of a single user request is limited, the number of user requests increase and these can be performed in parallel (task parallelism).

So there are quite a number of opportunities even for problems that seem fundamentally linear and that customers/developers can get for free.

Comment Re:Actually... (Score 3, Interesting) 141

As an outsider, that isn't what I see. AMD has bought most of its core technology rather than designing it from scratch. The K6 was from NexGen, the bus from DEC (Socket A, HyperTransport), the Athlon was a great traditional design (P6/Alpha/PowerPC-like in ideas), the memory controller experience came from Alpha hires, their embedded chip is based on Cyrix's, etc. AMD has been quite good at taking proven ideas and implementing them for the mass market with a lot of success. The primary innovations they are given credit for is the memory controller on x86 (first done Transmetta Crusoe), HyperTransport (DEC), and multi-core (IBM Power).

Intel always seemed to be an innovative company that heavily funds R&D, but can have utter flops by not being pragmatic enough to drop a bad design. While they fail badly, the ideas are usually quite unique and I'm sure educational. The fact that they recover rather than repeatedly making bad calls (e.g. Sun) shows that they are resilliant. Having the different design teams probably helps to both recover from a flop and not corrupt creativity by allowing groups to go into different directions. As you indicate, though, there are only so many good ideas and the duplication has to be extremely frustrating.

So I'm not sure if Intel's approach is bad and they tend to be more innovative than AMD. Its costly, though, and as a consumer I've happily gone with AMD/Cyrix/etc when Intel pushes a flop chip.


Are Windows 7 Testers Going Unheard? 394

nandemoari writes "Windows 7 beta testers are disputing whether or not Microsoft is taking notice of their feedback. The dispute follows a blog post by Steven Sinofsky, the man in charge of engineering Windows 7. He notes that in one week in January Microsoft received data through Windows 7's automatic feedback system every 15 seconds. According to Sinofsky, it's impossible to keep everyone happy. That's partly because there are only so many changes Microsoft can make to the system and still finish it, and partly because in many cases testers often have opposing views about a feature."
Operating Systems

FreeBSD 7.1 Released 324

Sol-Invictus writes "The FreeBSD Release Engineering Team is pleased to announce the availability of FreeBSD 7.1-RELEASE. This is the second release from the 7-STABLE branch which improves on the functionality of FreeBSD 7.0 and introduces some new features. Some of the highlights: The ULE scheduler is now the default in GENERIC kernels for amd64 and i386 architectures. The ULE scheduler significantly improves performance on multicore systems for many workloads. Support for using DTrace inside the kernel has been imported from OpenSolaris. DTrace is a comprehensive dynamic tracing framework. A new and much-improved NFS Lock Manager (NLM) client. Boot loader changes allow, among other things, booting from USB devices and booting from GPT-labeled devices. KDE updated to 3.5.10, GNOME updated to 2.22.3. DVD-sized media for the amd64 and i386 architectures."

Student Invention May Significantly Extend Mobile Device Battery Life 160

imamac writes with this excerpt from news out of Carleton University: "Atif Shamim, an electronics PhD student at Carleton University, has built a prototype that extends the battery life of portable gadgets such as the iPhone and BlackBerry, by getting rid of all the wires used to connect the electronic circuits with the antenna. ... The invention involves a packaging technique to connect the antenna with the circuits via a wireless connection between a micro-antenna embedded within the circuits on the chip. 'This has not been tried before — that the circuits are connected to the antenna wirelessly. They've been connected through wires and a bunch of other components. That's where the power gets lost,' Mr. Shamim said." The story's headline claims the breakthrough can extend battery life by up to 12 times, but that seems to be a misinterpretation of Shamim's claim that his method reduces the power required to operate the antenna by a factor of about 12; 3.3 mW down from 38 mW. The research paper (PDF) is available at the Microwave Journal. imamac adds, "Unlike many of the breakthroughs we read about here and elsewhere, this seems like it has a very high probability of market acceptance and actual implementation."

Magnetic Portals Connect Sun and Earth 235

MaxwellEdison writes "Scientists have discovered evidence of magnetic portals connecting the Earth and the Sun every 8 minutes. 'Several speakers at the Workshop have outlined how FTEs form: On the dayside of Earth (the side closest to the sun), Earth's magnetic field presses against the sun's magnetic field. Approximately every eight minutes, the two fields briefly merge or "reconnect," forming a portal through which particles can flow. The portal takes the form of a magnetic cylinder about as wide as Earth. The European Space Agency's fleet of four Cluster spacecraft and NASA's five THEMIS probes have flown through and surrounded these cylinders, measuring their dimensions and sensing the particles that shoot through.'"
Data Storage

Ext4 Advances As Interim Step To Btrfs 510's Kernel Log has a look at the ext4 filesystem as Linus Torvalds has integrated a large collection of patches for it into the kernel main branch. "This signals that with the next kernel version 2.6.28, the successor to ext3 will finally leave behind its 'hot' development phase." The article notes that ext4 developer Theodore Ts'o (tytso) is in favor of ultimately moving Linux to a modern, "next-generation" file system. His preferred choice is btrfs, and Heise notes an email Ts'o sent to the Linux Kernel Mailing List a week back positioning ext4 as a bridge to btrfs.
The Internet

Opera Develops Search Engine For Web Developers 31

nk497 writes "The Metadata Analysis and Mining Application (MAMA) doesn't index content like a standard search engine, but looks at markup, style, scripting and the technology behind pages. Based on those existing MAMA-ed pages, 80.4 per cent of sites use cascading style sheets (CSS), while the average web page has 47 markup errors and 16,400 characters. Should you want to know which country is using the AJAX component XMLHttpRequest the most, MAMA can tell you that it's Norway, with 10.2 per cent of the data set." Additional coverage is available at Computerworld, and a deeper explanation is up at Opera's Dev site.

Man Fails High School Exams For 38th Straight Year 5

You can call Shiv Charan simple, foolish, or just plain stupid if you want. The one thing you can't call him is a quitter. Starting in 1969, Shiv has devoted his life to passing India's year 10 exam. Since then he has taken the test every year except two (to study, I guess), and has failed every time. He has vowed not to marry until he can pass the test and is still single, which is now his main motivation. "As long as I am alive I will go on giving examinations in order to get a wife. For me, success is not merely about clearing the examinations. It will also throw open the doors of marriage," he said. By now Shiv must have the most impressive collection of prom wear in all of Asia. It seems like he'd pass just so he wouldn't have to dance to Alphaville's Forever young again.

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