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• How can a large, Fortran-based number crunching codebase be modernized?

  - by Dave Mateer

  A friend in academia asked me for advice (I'm a C# business application developer). He has a legacy codebase which he wrote in Fortran in the medical imaging field. It does a huge amount of number crunching using vectors. He uses a cluster (30ish cores) and has now gone towards a single workstation with 500ish GPUS in it. However where to go next with the codebase so: Other people can maintain it over next 10 year cycle Get faster at tweaking the software Can run on different infrastructures without recompiles After some research from me (this is a super interesting area) some options are: Use Python and CUDA from Nvidia Rewrite in a functional language. For example, F# or Haskell Go cloud based and use something like Hadoop and Java Learn C What has been your experience with this? What should my friend be looking at to modernize his codebase? UPDATE: Thanks @Mark and everyone who has answered. The reasons my friend is asking this question is that it's a perfect time in the projects lifecycle to do a review. Bringing research assistants up to speed in Fortran takes time (I like C#, and especially the tooling and can't imagine going back to older languages!!) I liked the suggestion of keeping the pure number crunching in Fortran, but wrapping it in something newer. Perhaps Python as that seems to be getting a stronghold in academia as a general-purpose programming language that is fairly easy to pick up. See Medical Imaging and a guy who has written a Fortran wrapper for CUDA, Can I legally publish my Fortran 90 wrappers to Nvidias' CUFFT library (from the CUDA SDK)?.

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• Polite busy-waiting with WRPAUSE on SPARC

  - by Dave

  Unbounded busy-waiting is an poor idea for user-space code, so we typically use spin-then-block strategies when, say, waiting for a lock to be released or some other event. If we're going to spin, even briefly, then we'd prefer to do so in a manner that minimizes performance degradation for other sibling logical processors ("strands") that share compute resources. We want to spin politely and refrain from impeding the progress and performance of other threads — ostensibly doing useful work and making progress — that run on the same core. On a SPARC T4, for instance, 8 strands will share a core, and that core has its own L1 cache and 2 pipelines. On x86 we have the PAUSE instruction, which, naively, can be thought of as a hardware "yield" operator which temporarily surrenders compute resources to threads on sibling strands. Of course this helps avoid intra-core performance interference. On the SPARC T2 our preferred busy-waiting idiom was "RD %CCR,%G0" which is a high-latency no-nop. The T4 provides a dedicated and extremely useful WRPAUSE instruction. The processor architecture manuals are the authoritative source, but briefly, WRPAUSE writes a cycle count into the the PAUSE register, which is ASR27. Barring interrupts, the processor then delays for the requested period. There's no need for the operating system to save the PAUSE register over context switches as it always resets to 0 on traps. Digressing briefly, if you use unbounded spinning then ultimately the kernel will preempt and deschedule your thread if there are other ready threads than are starving. But by using a spin-then-block strategy we can allow other ready threads to run without resorting to involuntary time-slicing, which operates on a long-ish time scale. Generally, that makes your application more responsive. In addition, by blocking voluntarily we give the operating system far more latitude regarding power management. Finally, I should note that while we have OS-level facilities like sched_yield() at our disposal, yielding almost never does what you'd want or naively expect. Returning to WRPAUSE, it's natural to ask how well it works. To help answer that question I wrote a very simple C/pthreads benchmark that launches 8 concurrent threads and binds those threads to processors 0..7. The processors are numbered geographically on the T4, so those threads will all be running on just one core. Unlike the SPARC T2, where logical CPUs 0,1,2 and 3 were assigned to the first pipeline, and CPUs 4,5,6 and 7 were assigned to the 2nd, there's no fixed mapping between CPUs and pipelines in the T4. And in some circumstances when the other 7 logical processors are idling quietly, it's possible for the remaining logical processor to leverage both pipelines. Some number T of the threads will iterate in a tight loop advancing a simple Marsaglia xor-shift pseudo-random number generator. T is a command-line argument. The main thread loops, reporting the aggregate number of PRNG steps performed collectively by those T threads in the last 10 second measurement interval. The other threads (there are 8-T of these) run in a loop busy-waiting concurrently with the T threads. We vary T between 1 and 8 threads, and report on various busy-waiting idioms. The values in the table are the aggregate number of PRNG steps completed by the set of T threads. The unit is millions of iterations per 10 seconds. For the "PRNG step" busy-waiting mode, the busy-waiting threads execute exactly the same code as the T worker threads. We can easily compute the average rate of progress for individual worker threads by dividing the aggregate score by the number of worker threads T. I should note that the PRNG steps are extremely cycle-heavy and access almost no memory, so arguably this microbenchmark is not as representative of "normal" code as it could be. And for the purposes of comparison I included a row in the table that reflects a waiting policy where the waiting threads call poll(NULL,0,1000) and block in the kernel. Obviously this isn't busy-waiting, but the data is interesting for reference. _table { border:2px black dotted; margin: auto; width: auto; } _tr { border: 2px red dashed; } _td { border: 1px green solid; } _table { border:2px black dotted; margin: auto; width: auto; } _tr { border: 2px red dashed; } td { background-color : #E0E0E0 ; text-align : right ; } th { text-align : left ; } td { background-color : #E0E0E0 ; text-align : right ; } th { text-align : left ; } Aggregate progress T = #worker threads Wait Mechanism for 8-T threadsT=1T=2T=3T=4T=5T=6T=7T=8 Park thread in poll() 32653347334833483348334833483348 no-op 415 831 124316482060249729303349 RD %ccr,%g0 "pause" 14262429269228623013316232553349 PRNG step 412 829 124616702092251029303348 WRPause(8000) 32443361333133483349334833483348 WRPause(4000) 32153308331533223347334833473348 WRPause(1000) 30853199322432513310334833483348 WRPause(500) 29173070315032223270330933483348 WRPause(250) 26942864294930773205338833483348 WRPause(100) 21552469262227902911321433303348

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• No keyboard input until after GRUB

  - by Dave M G

  I have a computer that I dual boot between Ubuntu 11.10 and Windows 7. I installed Windows first, and Ubuntu second. When I boot, the GRUB menu comes up, showing me the option to select to boot to Ubuntu at the top of the list, and to boot to Windows at the bottom. Unfortunately, as far as I can tell, any key I press on the keyboard (connected by USB) does not get any response, so I can't actually select to boot to anything but Ubuntu (which is the default selection). Once Ubuntu loads and I am at the log in screen, then the keyboard (and mouse) work perfectly normally thereafter. Why would my keyboard not work only during GRUB? And how do I fix it?

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• Silverlight Cream Monday WP7 App Review # 1

  - by Dave Campbell

  I'm going to try something here... if it seems useful, I'll continue, if it doesn't, I'll stop... so give me feedback! There are *lots* of Apps in the WP7 Marketplace, and heaven help me, but the Marketplace sucks for finding stuff. I won't rehash what's already been said in the blogs, but I agree with one and all. I went out last Saturday to find 2 apps that I knew were released, and couldn't do so on my device. Even in the Zune app, it took quite a while to find them... ok, I'll back off a bit, because I just found out I can do 'Search' now if I know the name... I didn't think that was working before. So my thought is on Monday (like today), I will post a review of 5 apps/games I either use or have played with on my device. These are strictly my opinions, you understand, but hey... it's better than a poke in the eye with an iPhone! A few disclaimers:     Feel free to write me about your app and tell me about it. While it would be very cool to receive a whole bunch of xap files to review, at this point, for technical reasons, I'm unable to side-load my device. Since I plan on only doing this one day a week, and only 5, I may never get caught up, so if you send me some info, be patient. Re: games ... remember I'm old... I'm from the era of Colossal Cave and Zork. Duke-Nukem 2D and Captain Comic were awesome. I don't own an XBOX or any other game system, so take game reviews from my perspective -- who knows, it may be refreshing :) I won't pay for an app or game just to try it. If you expect me to test-drive your app, it's going to have to have a Free Trial. In this Issue:   Jingo! is the first app I bought, just to see what the experience was like. It's very much like a game we used to play in school in the Army in 1971 on paper we passed around. Sort of a cross between hangman and Mastermind, you try to figure out the hidden word in 5 tries. You get really good at 5-letter words after a while. I like this because you have to think, and you're not pressured by a clock Jingo! is by James Furdell and is $1.99 I reviewed René Schulte's Pictures Lab a while back, and have not changed my mind. This is an excellent app for playing with any photo on your device... one you've just taken, one you've synced from your PC, or one you've saved from email. I like this because you can get some cool effects for your photos, and it just works. Pictures Lab is by Schulte Software Development and is $1.99 Since I work as a consultant, and from home, I wanted something I could track my time with. I've test-driven all the contenders I could find so far on the phone, and so far I like ONTRACK! the best. If asked, I have some suggestions, but it's probably just the way I work or think. What I do like is I can tap a project to start/stop/restart a counter, and at the end of the day it shows me how much time I've been working. If there's a way to make an adjustment in case you forget to tap the counter, I don't know how to do it, and that's my biggest complaint. I like this because you can get a daily readout which you can also email as a spreadsheet. The daily results display is very good. ONTRACK! is by Qmino and is $2.99 Remember Item 4 above... I've been playing guitar for 48 years... obviously since before the invention of 'tuners', so I'm not as dependent upon these as some folks are. I've tried some in the past and have always felt I can do just as good by ear (I have perfect relative pitch). So, I gave this app by András Velvárt a dance just to see how it works, and it is surprisingly good. If you're used to one of the stage tuners this may take a little getting used to, but it does the job. The difference with this one is there is no real 'null' point inside which you can think your guitar is in tune. The soundwave stays visible on the device, and if it's moving to the right, your string is flat, if it's moving to the left, your string is sharp. Getting it exact might be tricky, but it is exact! If you need to rely on a tuner, this is a good choice in my opinion, exactly because of the sensitivity.. tune up with this and you're dead-on. Guitar Tuner is by Kinabalu Innovation Limited and is $0.99 Popper 2 is the WP7 version of a wildly popular game by Bill Reiss named Dr. Popper. You can get a trial, or you can now get a free lite version of the game. Popper 2 is a fast-paced bubble breaker game. I find it something fun to play when I just want to buzz out, but maybe the best review is that my daughter didn't want to give my phone back when I showed it to her, and always wants to grab my phone to play 'that game'. A fun distraction with great graphics and a great price Popper 2 is by Blue Rose Systems, LLC and is $1.29 Let me know what you think of the idea of doing reviews, or the layout/whatever, and Stay in the 'Light!   Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• Cross Apply Ambiguity

  - by Dave Ballantyne

  Cross apply (and outer apply)  are a very welcome addition to the TSQL language.  However, today after a few hours of head scratching, I have found an simple issue which could cause big big problems. What would you expect from this statement ? select * from sys.objects b join sys.objects a on a.object_id = object_id No prizes for guessing SQL server errors with “Ambiguous column name 'object_id'”. What would you expect from this statement ? Select * from sys.objects a cross apply( Select * from sys.objects b where b.object_id = object_id) as c Surprisingly, perhaps, the result is a cross join of sys.objects.  Well, what happened there ? If you look at the apply statement, within the where clause, only one of the conditions is qualified with a table name.  This meant that is has be interpreted as “b.object_id = b.object_id” causing the cross apply to have no join the the parent sys.objects table and causing the cross join. The fix is , obviously, simple Select * from sys.objects a cross apply( Select * from sys.objects b where b.object_id = a.object_id) as c So why no “Ambiguous column name ” error ?  I’ve raised a connect item on this issue here.

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• SilverlightShow for 06-12 Dec 2010

  - by Dave Campbell

  In an effort to get some synergy in the Silverlight community, the SilverlightShow folks and I have decided to share some information. As always, I'm running a bit behind, so I get to post first with the material they provided to me :) Check out the five most popular news at SilverlightShow for last week (06 - 12 Dec 2010). The news that hit the top is the announcement for the upcoming SilverlightShow webinar with Gill Cleeren [which I posted about a couple weeks ago] (check other webinars Gill delivered for SilverlightShow) and the free Telerik license given away to attendees. Michael Crump's digest of Silverlight 5 news announced at Firestarter was the next most attention-grabbing news. Here is SilverlightShow's weekly top 5: Join our next webinar and win a license for Telerik RadControls for Silverlight Silverlight 5 - What's New (Including Screenshots & Code Snippets) Glossy TextBlock Custom Control For Windows Phone WP7 development vs iOS, Android and mobile Web Silverlight Simple Drag And Drop / Or Browse View Model / MVVM File Upload Control Visit and bookmark SilverlightShow... they've got a lot of good things happening over there. Stay in the 'Light

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• Google analytics and Adwords showing very different figures

  - by Dave Rook

  In AdWords I have 1 advert running only. The landing page includes a querystring so I can track it. EG, www.mydomain.com/products?source=CPC I also use Google Analytics. For February I have approx 1450 clicks in AdWords. This means, 1450 went to my website. In Google Analytics, according to my landing page, there were only ~850 visits. In Google Analytics, in the Acquisition - All traffic page, it suggests that Google CPC brought 517 visits... I know tracking tools are not 100% reliable but this figure seems to be showing something is very wrong. How can I tell which of the figures is accurate or is this just a limitation of reporting tools?

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• I&rsquo;m back, now with Windows Live Writer goodness

  - by Dave Yasko

  I’ve reimaged my home laptop.  I’m trying to populate it with as much free goodness as possible to see if the free way is as good as the old pay way.  Turns out, I’ve got access to Windows Live Writer.  I’m not sure where that came from, maybe with Vista Ultimate.  I don’t know.  Either way, it makes my blog posting a whole lot easier.  So, maybe, just maybe, it will make me more likely to post.  We’ll see. Later.

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• Activist shared printing material gallery

  - by Dave

  What would you say would be the best way to do this: We would like to create a section on our activist community FB page and website in order to share with everyone images and files ready for printing panflets, brochures, t-shirts, stickers, etc. Let's say we have some cool slogans for t-shirts, so we would like to show them on a gallery, and offer for download the original design files needed for a print shop to create the t-shirts. And the same thing for all other kinds of media. We want to enable anyone to be able to just download the files for free, and easily create printed materials with them. But besides offering this hybrid between picture gallery and downloads manager, we would also like to make it very easy for anyone to upload and share their own files with the community, to make it a true collaboration initiative, be it that they get posted automatically, or that we first review and approve all uploads. Cafepress or Spreadshirt let you upload your design and sell your own merchandise. We need something similar, but where people can then download working files for making quality printings and materials. What apps, tools, services or methods are out there with which you think this could be best done?? We have some ideas, but we would like to hear some more!!

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• Why does my system use so much cache?

  - by Dave M G

  Previously, on my desktop computer running Ubuntu 14.04, I had 4GB RAM, which I thought should be plenty. However, after being on for a while, my computer would seem to get slow. I have a system resource monitor app in my Gnome panel, which I assume represents the available RAM (?). It shows a dark green area as being "Memory", and a light green area as "Cache". The "Cache" would slowly grow until it filled the whole graph, and then programs would get slow to load, or it would take a while to switch programs. I could alleviate the problem somewhat with this command, but eventually the computer cache fills up again, so it's only a bandaid: sudo sh -c "sync; echo 3 > /proc/sys/vm/drop_caches" So, I figured I'd get more RAM, so I replaced one 2GB stick with an 8GB stick, and now I have 10 GB ram. And my "cache" still slowly maxes out and my computer slows as a result. Also, sometimes the computer starts out with "cache" maxed when I first boot and log in. Not always though, I don't know if there's a pattern that determines why it happens. Why is Ubuntu using up so much cache? Is 10GB not enough for Ubuntu? Here's what my system monitor looks like in my Gnome panel. The middle square shows RAM usage. The light green area is the "cache": This is my memory and swap history, which doesn't seem to include any information about "cache". I realize at this point I'm not totally clear on the difference between "cache" and "swap":

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• NUMA-aware placement of communication variables

  - by Dave

  For classic NUMA-aware programming I'm typically most concerned about simple cold, capacity and compulsory misses and whether we can satisfy the miss by locally connected memory or whether we have to pull the line from its home node over the coherent interconnect -- we'd like to minimize channel contention and conserve interconnect bandwidth. That is, for this style of programming we're quite aware of where memory is homed relative to the threads that will be accessing it. Ideally, a page is collocated on the node with the thread that's expected to most frequently access the page, as simple misses on the page can be satisfied without resorting to transferring the line over the interconnect. The default "first touch" NUMA page placement policy tends to work reasonable well in this regard. When a virtual page is first accessed, the operating system will attempt to provision and map that virtual page to a physical page allocated from the node where the accessing thread is running. It's worth noting that the node-level memory interleaving granularity is usually a multiple of the page size, so we can say that a given page P resides on some node N. That is, the memory underlying a page resides on just one node. But when thinking about accesses to heavily-written communication variables we normally consider what caches the lines underlying such variables might be resident in, and in what states. We want to minimize coherence misses and cache probe activity and interconnect traffic in general. I don't usually give much thought to the location of the home NUMA node underlying such highly shared variables. On a SPARC T5440, for instance, which consists of 4 T2+ processors connected by a central coherence hub, the home node and placement of heavily accessed communication variables has very little impact on performance. The variables are frequently accessed so likely in M-state in some cache, and the location of the home node is of little consequence because a requester can use cache-to-cache transfers to get the line. Or at least that's what I thought. Recently, though, I was exploring a simple shared memory point-to-point communication model where a client writes a request into a request mailbox and then busy-waits on a response variable. It's a simple example of delegation based on message passing. The server polls the request mailbox, and having fetched a new request value, performs some operation and then writes a reply value into the response variable. As noted above, on a T5440 performance is insensitive to the placement of the communication variables -- the request and response mailbox words. But on a Sun/Oracle X4800 I noticed that was not the case and that NUMA placement of the communication variables was actually quite important. For background an X4800 system consists of 8 Intel X7560 Xeons . Each package (socket) has 8 cores with 2 contexts per core, so the system is 8x8x2. Each package is also a NUMA node and has locally attached memory. Every package has 3 point-to-point QPI links for cache coherence, and the system is configured with a twisted ladder "mobius" topology. The cache coherence fabric is glueless -- there's not central arbiter or coherence hub. The maximum distance between any two nodes is just 2 hops over the QPI links. For any given node, 3 other nodes are 1 hop distant and the remaining 4 nodes are 2 hops distant. Using a single request (client) thread and a single response (server) thread, a benchmark harness explored all permutations of NUMA placement for the two threads and the two communication variables, measuring the average round-trip-time and throughput rate between the client and server. In this benchmark the server simply acts as a simple transponder, writing the request value plus 1 back into the reply field, so there's no particular computation phase and we're only measuring communication overheads. In addition to varying the placement of communication variables over pairs of nodes, we also explored variations where both variables were placed on one page (and thus on one node) -- either on the same cache line or different cache lines -- while varying the node where the variables reside along with the placement of the threads. The key observation was that if the client and server threads were on different nodes, then the best placement of variables was to have the request variable (written by the client and read by the server) reside on the same node as the client thread, and to place the response variable (written by the server and read by the client) on the same node as the server. That is, if you have a variable that's to be written by one thread and read by another, it should be homed with the writer thread. For our simple client-server model that means using split request and response communication variables with unidirectional message flow on a given page. This can yield up to twice the throughput of less favorable placement strategies. Our X4800 uses the QPI 1.0 protocol with source-based snooping. Briefly, when node A needs to probe a cache line it fires off snoop requests to all the nodes in the system. Those recipients then forward their response not to the original requester, but to the home node H of the cache line. H waits for and collects the responses, adjudicates and resolves conflicts and ensures memory-model ordering, and then sends a definitive reply back to the original requester A. If some node B needed to transfer the line to A, it will do so by cache-to-cache transfer and let H know about the disposition of the cache line. A needs to wait for the authoritative response from H. So if a thread on node A wants to write a value to be read by a thread on node B, the latency is dependent on the distances between A, B, and H. We observe the best performance when the written-to variable is co-homed with the writer A. That is, we want H and A to be the same node, as the writer doesn't need the home to respond over the QPI link, as the writer and the home reside on the very same node. With architecturally informed placement of communication variables we eliminate at least one QPI hop from the critical path. Newer Intel processors use the QPI 1.1 coherence protocol with home-based snooping. As noted above, under source-snooping a requester broadcasts snoop requests to all nodes. Those nodes send their response to the home node of the location, which provides memory ordering, reconciles conflicts, etc., and then posts a definitive reply to the requester. In home-based snooping the snoop probe goes directly to the home node and are not broadcast. The home node can consult snoop filters -- if present -- and send out requests to retrieve the line if necessary. The 3rd party owner of the line, if any, can respond either to the home or the original requester (or even to both) according to the protocol policies. There are myriad variations that have been implemented, and unfortunately vendor terminology doesn't always agree between vendors or with the academic taxonomy papers. The key is that home-snooping enables the use of a snoop filter to reduce interconnect traffic. And while home-snooping might have a longer critical path (latency) than source-based snooping, it also may require fewer messages and less overall bandwidth. It'll be interesting to reprise these experiments on a platform with home-based snooping. While collecting data I also noticed that there are placement concerns even in the seemingly trivial case when both threads and both variables reside on a single node. Internally, the cores on each X7560 package are connected by an internal ring. (Actually there are multiple contra-rotating rings). And the last-level on-chip cache (LLC) is partitioned in banks or slices, which with each slice being associated with a core on the ring topology. A hardware hash function associates each physical address with a specific home bank. Thus we face distance and topology concerns even for intra-package communications, although the latencies are not nearly the magnitude we see inter-package. I've not seen such communication distance artifacts on the T2+, where the cache banks are connected to the cores via a high-speed crossbar instead of a ring -- communication latencies seem more regular.

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• How do I turn on wireless adapter on HP Envy dv6 7200 under Ubuntu (any version)?

  - by Dave B.

  I have a new HP Envy dv6 7200 with dual boot Windows 8 / Ubuntu 12.04. In windows, the F12 key in Windows activates the "airplane mode" switch which enables/disables both on-board (mini PCIe) and USB wireless adapters. In Ubuntu, however, the wireless adapter is turned off by default and cannot be turned back on via the F12 key (or any other combination of F12 and Ctrl, Fn, Shift, etc.). Let me explain the "fixes" I've seen in various forums and explain what did or did not happen. These are listed in no particular order. (Spoiler alert: wireless is still broke). Solution 1? Use HP's "Wireless Assistant" utility to permanently activate the wireless card in Windows, then boot into Ubuntu to happily find it working. Unfortunately, this utility works in Windows 7 but not Windows 8. On the other hand, hardware drivers from HP are only available for Windows 8 for this model. Catch 22 (I could not find a comparable utility for Windows 8). Solution 2? Use a USB wireless adapter to sidestep the on-board device. I purchased such a device from thinkpenguin.com to be sure that it would be Linux-friendly. However, the wireless switch enables / disables all wireless devices including USB. So, there's my $50 donation to the nice folks at thinkpenguin.com, but still no solution. Solution 3? Following the Think Penguin folk's suggestion, modify the mini PCI express adapter following instructions here: http://www.notebookforums.com/t/225429/broken-wireless-hardware-switch-fix Tempting, but I then violate the terms of my warranty mere days after opening the box. This might be a good solution for an older machine that you want to get your geek on with, but not for a new box. Solution 4? rfkill unblock all No effect whatsoever. ubuntu@ubuntu-hp-evny:~$ rfkill unblock all ubuntu@ubuntu-hp-evny:~$ rfkill list all 0: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: yes Solution 5? Re-install drivers. Done and done. Ubuntu recognizes the device - perhaps even without re-installing the drivers? - but cannot turn it on. How do I know this? In the Network Manager drop-down menu, the wireless option is blacked out and a message reads something like: "wireless network is disabled by a hardware switch". Solution 6? Identify a physical switch on the laptop and flip it. There is no such switch on this machine. In fact, walking through Best Buy yesterday, I checked and not a single new laptop PC had a physical switch on it. All of the wireless switches are either the F2 or F12 key ... I wonder if askubuntu will not be plagued by this exact issue in the near future? Additional info - lspci ubuntu@ubuntu-hp-evny:~$ lspci 00:00.0 Host bridge: Intel Corporation Ivy Bridge DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Ivy Bridge PCI Express Root Port (rev 09) 00:02.0 VGA compatible controller: Intel Corporation Ivy Bridge Graphics Controller (rev 09) 00:14.0 USB controller: Intel Corporation Panther Point USB xHCI Host Controller (rev 04) 00:16.0 Communication controller: Intel Corporation Panther Point MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation Panther Point High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 1 (rev c4) 00:1c.2 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 3 (rev c4) 00:1c.3 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 4 (rev c4) 00:1c.5 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 6 (rev c4) 00:1d.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation Panther Point LPC Controller (rev 04) 00:1f.2 RAID bus controller: Intel Corporation 82801 Mobile SATA Controller [RAID mode] (rev 04) 00:1f.3 SMBus: Intel Corporation Panther Point SMBus Controller (rev 04) 01:00.0 VGA compatible controller: NVIDIA Corporation Device 0de9 (rev a1) 08:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device 5229 (rev 01) 0a:00.0 Network controller: Ralink corp. Device 539b 0b:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 07) Any suggestions would be much appreciated!

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• Indexed view deadlocking

  - by Dave Ballantyne

  Deadlocks can be a really tricky thing to track down the root cause of.  There are lots of articles on the subject of tracking down deadlocks, but seldom do I find that in a production system that the cause is as straightforward.  That being said,  deadlocks are always caused by process A needs a resource that process B has locked and process B has a resource that process A needs.  There may be a longer chain of processes involved, but that is the basic premise. Here is one such (much simplified) scenario that was at first non-obvious to its cause: The system has two tables,  Products and Stock.  The Products table holds the description and prices of a product whilst Stock records the current stock level. USE tempdb GO CREATE TABLE Product ( ProductID INTEGER IDENTITY PRIMARY KEY, ProductName VARCHAR(255) NOT NULL, Price MONEY NOT NULL ) GO CREATE TABLE Stock ( ProductId INTEGER PRIMARY KEY, StockLevel INTEGER NOT NULL ) GO INSERT INTO Product SELECT TOP(1000) CAST(NEWID() AS VARCHAR(255)), ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM sys.columns a CROSS JOIN sys.columns b GO INSERT INTO Stock SELECT ProductID,ABS(CAST(CAST(NEWID() AS VARBINARY(255)) AS INTEGER))%100 FROM Product There is a single stored procedure of GetStock: Create Procedure GetStock as SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 Analysis of the system showed that this procedure was causing a performance overhead and as reads of this data was many times more than writes,  an indexed view was created to lower the overhead. CREATE VIEW vwActiveStock With schemabinding AS SELECT Product.ProductID,Product.ProductName FROM dbo.Product join dbo.Stock on Stock.ProductId = Product.ProductID where Stock.StockLevel <> 0 go CREATE UNIQUE CLUSTERED INDEX PKvwActiveStock on vwActiveStock(ProductID) This worked perfectly, performance was improved, the team name was cheered to the rafters and beers all round.  Then, after a while, something else happened… The system updating the data changed,  The update pattern of both the Stock update and the Product update used to be: BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT BEGIN TRAN UPDATE... COMMIT It changed to: BEGIN TRAN UPDATE... UPDATE... UPDATE... COMMIT Nothing that would raise an eyebrow in even the closest of code reviews.  But after this change we saw deadlocks occuring. You can reproduce this by opening two sessions. In session 1 begin transaction Update Product set ProductName ='Test' where ProductID = 998 Then in session 2 begin transaction Update Stock set Stocklevel = 5 where ProductID = 999 Update Stock set Stocklevel = 5 where ProductID = 998 Hop back to session 1 and.. Update Product set ProductName ='Test' where ProductID = 999 Looking at the deadlock graphs we could see the contention was between two processes, one updating stock and the other updating product, but we knew that all the processes do to the tables is update them.  Period.  There are separate processes that handle the update of stock and product and never the twain shall meet, no reason why one should be requiring data from the other.  Then it struck us,  AH the indexed view. Naturally, when you make an update to any table involved in a indexed view, the view has to be updated.  When this happens, the data in all the tables have to be read, so that explains our deadlocks.  The data from stock is read when you update product and vice-versa. The fix, once you understand the problem fully, is pretty simple, the apps did not guarantee the order in which data was updated.  Luckily it was a relatively simple fix to order the updates and deadlocks went away.  Note, that there is still a *slight* risk of a deadlock occurring, if both a stock update and product update occur at *exactly* the same time.

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• Silverlight Cream for January 15, 2011 -- #1028

  - by Dave Campbell

  Note to #1024 Swag Winners: I'm sending emails to the vendors Sunday night, thanks for your patience (a few of you have not contacted me yet) In this Issue: Ezequiel Jadib, Daniel Egan(-2-), Page Brooks, Jason Zander, Andrej Tozon, Marlon Grech, Jonathan van de Veen, Walt Ritscher, Jesse Liberty, Jeremy Likness, Sacha Barber, William E. Burrows, and WindowsPhoneGeek. Above the Fold: Silverlight: "Building a Radar Control in Silverlight - Part 1" Page Brooks WP7: "Tutorial: Dynamic Tile Push Notification for Windows Phone 7" Jason Zander Training: "WP7 Unleashed Session I–Hands on Labs" Daniel Egan From SilverlightCream.com: Silverlight Rough Cut Editor SP1 Released Ezequiel Jadib has an announcement about the Rough Cut Editor SP1 release, and he walks you through the content, installation and a bit of the initial use. WP7 Unleashed Session I–Hands on Labs Daniel Egan posted Part 1 of 3 of a new WP7 HOL ... video online and material to download... get 'em while they're hot! WP7 Saving to Media Library Daniel Egan has another post up as well on saving an image to the media library... not the update from Tim Heuer... all good info Building a Radar Control in Silverlight - Part 1 This freakin' cool post from Page Brooks is the first one of a series on building a 'Radar Control' in Silverlight ... seriously, go to the bottom and run the demo... I pretty much guarantee you'll take the next link which is download the code... don't forget to read the article too! Tutorial: Dynamic Tile Push Notification for Windows Phone 7 Jason Zander has a nice-looking tutorial up on dynamic tile notifications... good diagrams and discussion and plenty of code. Reactive.buffering.from event. Andrej Tozon is continuing his Reactive Extensions posts with this one on buffering: BufferWithTime and BufferWIthCount ... good stuff, good write-up, and the start of a WP7 game? MEFedMVVM with PRISM 4 Marlon Grech combines his MEFedMVVM with Prism 4, and says it was easy... check out the post and the code. Adventures while building a Silverlight Enterprise application part #40 Jonathan van de Veen has a discussion up about things you need to pay attention to as your project gets close to first deployment... lots of good information to think about Silverlight or not. Customize Windows 7 Preview pane for XAML files Walt Ritscher has a (very easy) XAML extension for Windows 7 that allows previewing of XAML files in an explorer window... as our UK friends say "Brilliant!" Entity Framework Code-First, oData & Windows Phone Client From the never-ending stream of posts that is Jesse Liberty comes this one on EF Code-First... so Jesse's describing Code-First and OData all wrapped up about a WP7 app Sterling Silverlight and Windows Phone 7 Database Triggers and Auto-Identity Sterling and Database Triggers sitting in a tree... woot for WP7 from Jeremy Likness... provides database solutions including Validation, Data-specific concerns such as 'last modified', and post-save processing ... all good, Jeremy! A Look At Fluent APIs Sacha Barber has a great post up that isn't necessarily Silverlight, but is it? ... we've been hearing a lot about Fluent APIs... read on to see what the buzz is. Windows Phone 7 - Part 3 - Final Application William E. Burrows has Part 3 of his WP7 tutorial series up... this one completing the Golf Handicap app by giving the user the ability to manage scores. User Control vs Custom Control in Silverlight for WP7 WindowsPhoneGeek has a great diagram and description-filled post up on User Controls and Custom Controls in WP7... good external links too. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• Drawing isometric map in canvas / javascript

  - by Dave

  I have a problem with my map design for my tiles. I set player position which is meant to be the middle tile that the canvas is looking at. How ever the calculation to put them in x:y pixel location is completely messed up for me and i don't know how to fix it. This is what i tried: var offset_x = 0; //used for scrolling on x var offset_y = 0; //used for scrolling on y var prev_mousex = 0; //for movePos function var prev_mousey = 0; //for movePos function function movePos(e){ if (prev_mousex === 0 && prev_mousey === 0) { prev_mousex = e.pageX; prev_mousey = e.pageY; } offset_x = offset_x + (e.pageX - prev_mousex); offset_y = offset_y + (e.pageY - prev_mousey); prev_mousex = e.pageX; prev_mousey = e.pageY; run = true; } player_posx = 5; player_posy = 55; ct = 19; for (i = (player_posx-ct); i < (player_posx+ct); i++){ //horizontal for (j=(player_posy-ct); j < (player_posy+ct); j++){ // vertical //img[0] is 64by64 but the graphic is 64by32 the rest is alpha space var x = (i-j)*(img[0].height/2) + (canvas.width/2)-(img[0].width/2); var y = (i+j)*(img[0].height/4); var abposx = x - offset_x; var abposy = y - offset_y; ctx.drawImage(img[0],abposx,abposy); } } Now based on these numbers the first render-able tile is I = 0 & J = 36. As numbers in the negative are not in the array. But for I=0 and J= 36 the position it calculates is : -1120 : 592 Does any one know how to center it to canvas view properly?

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• How to determine where on a path my object will be at a given point in time?

  - by Dave

  I have map and an obj that is meant to move from start to end in X amount of time. The movements are all straight lines, as curves are beyond my ability at the moment. So I am trying to get the object to move from these points, but along the way there are way points which keep it on a given path. The speed of the object is determined by how long it will take to get from start to end (based on X). This is what i have so far: //get_now() returns seconds since epoch var timepassed = get_now() - myObj[id].start; //seconds since epoch for departure var timeleft = myObj[id].end - get_now(); //seconds since epoch for arrival var journey_time = 60; //this means 60 minutes total journey time var array = [[650,250]]; //way points along the straight paths if(step == 0 || step =< array.length){ var destinationx = array[step][0]; var destinationy = array[step][1]; }else if( step == array.length){ var destinationx = 250; var destinationy = 100; } else { var destinationx = myObj[id].startx; var destinationy = myObj[id].starty; } step++; When the user logs in at any given time, the object needs to be drawn in the correct place of the path, almost as if its been travelling along the path whilst the user has not been at the PC with the available information i have above. How do I do this? Note: The camera angle in the game is a birds eye view so its a straight forward X:Y rather than isometric angles.

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• SilverlightShow for Feb 21 - 27, 2011

  - by Dave Campbell

  Check out the Top Five most popular news at SilverlightShow for Feb 21 - 27, 2011. Here are the top 5 news on SilverlightShow for last week: An Interview with Jeff Wilcox about his work with Silverlight and the Silverlight Toolkit Free SilverlightShow Webinar - Building LOB Apps with Silverlight and WCF Data Services ReSharper C# snippet for MVVM ViewModel Property creation Silverlight 4: Creating useful base classes for your views and viewmodels with PRISM 4 Free SilverlightShow Webinar: WCF RIA Services Validation Visit and bookmark SilverlightShow. Stay in the 'Light

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• Silverlight Cream Top Posted Authors July to December, 2010

  - by Dave Campbell

  It's past the first of January, and it's now time to recognize devs that have a large number of posts in Silverlight Cream. Ground Rules I pick what posts are on the blog Only posts that go in the database are included The author has to appear in SC at least 4 of the 6 months considered I averaged the monthly posts and am only showing Authors with an average greater than 1. Here are the Top Posted Authors at Silverlight Cream for July 1, 2010 through December 31, 2010: It is my intention to post a new list sometime shortly after the 1st of every month to recognize the top posted in the previous 6 months, so next up is January 1! Some other metrics for Silverlight Cream: At the time of this posting there are 7304 articles aggregated and searchable by partial Author, partial Title, keywords (in the synopsis), or partial URL. There are also 118 tags by which the articles can be searched. This is an increase of 317 posts over last month. At the time of this posting there are 783 articles tagged wp7dev. This is an increase of 119 posts over last month, or over a third of the posts added. Stay in the 'Light!

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• no back light on my acer aspire 5734z

  - by Dave

  I installed Ubuntu (12.04) on my acer aspire 5734z and the back light stopped working. I have tried the fix by editing the grub file posted on here a couple of days ago but that hasn't fixed it. I have also looked for hardware drivers but that didn't get me anywhere. When I hook up an external monitor it works fine but i have been unsuccessful getting the laptop display to light up. Thanks edit removed link I found a fix here " http://crunchbanglinux.org/forums/post/66562/#p66562 " if anyone has a better fix than the one in that post, let me know.

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• GameplayScreen does not contain a definition for GraphicsDevice

  - by Dave Voyles

  Long story short: I'm trying to intergrate my game with Microsoft's Game State Management. In doing so I've run into some errors, and the latest one is in the title. I'm not able to display my HUD for the reasons listed above. Previously, I had much of my code in my Game.cs class, but the GSM has a bit of it in Game1, and most of what you have drawn for the main screen in your GameplayScreen class, and that is what is causing confusion on my part. I've created an instance of the GameplayScreen class to be used in the HUD class (as you can see below). Before integrating with the GSM however, I created an instance of my Game class, and all worked fine. It seems that I need to define my graphics device somewhere, but I am not sure of where exactly. I've left some code below to help you understand. public class GameStateManagementGame : Microsoft.Xna.Framework.Game { #region Fields GraphicsDeviceManager graphics; ScreenManager screenManager; // Creates a new intance, which is used in the HUD class public static Game Instance; // By preloading any assets used by UI rendering, we avoid framerate glitches // when they suddenly need to be loaded in the middle of a menu transition. static readonly string[] preloadAssets = { "gradient", }; #endregion #region Initialization /// <summary> /// The main game constructor. /// </summary> public GameStateManagementGame() { Content.RootDirectory = "Content"; graphics = new GraphicsDeviceManager(this); graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; graphics.IsFullScreen = false; graphics.ApplyChanges(); // Create the screen manager component. screenManager = new ScreenManager(this); Components.Add(screenManager); // Activate the first screens. screenManager.AddScreen(new BackgroundScreen(), null); //screenManager.AddScreen(new MainMenuScreen(), null); screenManager.AddScreen(new PressStartScreen(), null); } namespace Pong { public class HUD { public void Update(GameTime gameTime) { // Used in the Draw method titleSafeRectangle = new Rectangle (GameplayScreen.Instance.GraphicsDevice.Viewport.TitleSafeArea.X, GameplayScreen.Instance.GraphicsDevice.Viewport.TitleSafeArea.Y, GameplayScreen.Instance.GraphicsDevice.Viewport.TitleSafeArea.Width, GameplayScreen.Instance.GraphicsDevice.Viewport.TitleSafeArea.Height); } } } class GameplayScreen : GameScreen { #region Fields ContentManager content; public static GameStates gamestate; private GraphicsDeviceManager graphics; public int screenWidth; public int screenHeight; private Texture2D backgroundTexture; private SpriteBatch spriteBatch; private Menu menu; private SpriteFont arial; private HUD hud; Animation player; // Creates a new intance, which is used in the HUD class public static GameplayScreen Instance; public GameplayScreen() { TransitionOnTime = TimeSpan.FromSeconds(1.5); TransitionOffTime = TimeSpan.FromSeconds(0.5); } protected void Initialize() { lastScored = false; menu = new Menu(); resetTimer = 0; resetTimerInUse = true; ball = new Ball(content, new Vector2(screenWidth, screenHeight)); SetUpMulti(); input = new Input(); hud = new HUD(); // Places the powerup animation inside of the surrounding box // Needs to be cleaned up, instead of using hard pixel values player = new Animation(content.Load<Texture2D>(@"gfx/powerupSpriteSheet"), new Vector2(103, 44), 64, 64, 4, 5); // Used by for the Powerups random = new Random(); vec = new Vector2(100, 50); vec2 = new Vector2(100, 100); promptVec = new Vector2(50, 25); timer = 10000.0f; // Starting value for the cooldown for the powerup timer timerVector = new Vector2(10, 10); //JEP - one time creation of powerup objects playerOnePowerup = new Powerup(); playerOnePowerup.Activated += PowerupActivated; playerOnePowerup.Deactivated += PowerupDeactivated; playerTwoPowerup = new Powerup(); playerTwoPowerup.Activated += PowerupActivated; playerTwoPowerup.Deactivated += PowerupDeactivated; //JEP - moved from events since these only need set once activatedVec = new Vector2(100, 125); deactivatedVec = new Vector2(100, 150); powerupReady = false; }

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• Why is NDA so hard to understand?

  - by Dave Campbell

  Maybe this concept is simpler for me because of all the jobs I've been on over the years requiring security clearances. I've signed quite a few NDA forms. Some for big companies, some for small, but the meaning of "NDA" remains constant: Non-Disclosure Agreement. To me, that takes no further explanation, but apparently it's confusing to some people, and I don't understand how you can be confused. The papers I signed with the U.S. Army in 1970 read "10 years and $10,000" for a violation... can't imagine what it's up to now, but THAT is a strict NDA :) So those things I've been told, I cannot talk about, period. Even if the entire world knows about them, I cannot speak about them until the information goes off NDA. An example was a Silverlight release a while back. It might have been Silverlight 3, I don't remember. Everyone was anxiously awaiting the release so they could post their material. Of course the entire world knew it was coming out and imminently so. Some enterprising folks had even found the bits on a server before the official announcement. So then the situation became: everyone knew about it, some were even coding with it and blogging about it and yet we couldn't talk about it. Scott Guthrie's posting about it opened the flood gates and then it went off NDA, but up until that moment, we were locked. Sitting out on the edge you're uninstalling and re-installing all the time and you get frustrated when things that used to work don't, but hey... those bits were still warm when you got 'em, and that's the fun. But that fun comes at a price, and the price is the NDA. Awkward yes, confusing no... See you at MIX10, and Stay in the 'Light! MIX10

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• Silverlight Cream Monday WP7 App Review # 2

  - by Dave Campbell

  Today's Review (alphabetic order): GooNews, Grocery Shopping List, Need for Speed, SurfCube, and United Nations News. I'm a day late if these are going to be 'Monday' posts, but there are lots of apps, lots of goodness, and lots of email, so I might try to do 2 a week, we'll see. So once again I've got a small review of 5 apps that are either on my phone or have been. Disclaimers at the end. In this Issue:   GooNews is a very cool app from Shawn Wildermuth (AgiliTrain). I don't know if he uses this as a demo during his instruction, but it definitely serves a purpose... wanna pick up the top news items from Google on a never-ending basis? ... this is it. You can add your own keyword searches, and send stories to InstaPaper or share via email. I like this because it brings me the news quickly and updated, and works great. GooNews is by AgiliTrain and is Free This was a request by the author, and actually surprised me. I'm a big one for lists, but I would have just done a OneNote list to SkyDrive and to my phone. This app is a lot more than that, but will take you some setup to make it be 'yours'. For obvious reasons, there are no unit prices on things, so you have to set that up to get some idea of the cost of what you're shopping for. But if you do that, you'll get a nice total. Lots of thought went into the various categories and you can add your own. There's a bit of animation on the category selection that's nice. He seems to have covered all the bases necessary to use this, even shopping 'plans' that can be saved, and emailing of lists. As I said, I'm more of a raw list person, but if you take the time to set this up, it should work very nicely for you. Grocery Shopping List is by Grocery Shopper and is $0.99 ($1.99 after Feb 1) with a free trial. This was my 2nd commercial game I bought, and the one I've played the most. I ran the trial, thought it worked great, and bought it. I've had a lot of fun with this... there's no gas pedal.. your foot is in the carbeurator from the GO!, and unless you wanna tap the screen and brake like a little girl, just hang onto the steering wheel (the phone), and guide your way through. Hours of fun and challenges here. I like this because it's got some challenge to it, and the cars seem to be very realistic in their reactions. Need for Speed Undercover is by Electronic Arts is $4.99 and has a free trial. SurfCube Browser is another app by the folks that did the GuitarTuner I reviewed on Monday. You have to see SurfCube to believe it. You've probably seen the YouTube video, if not check SilverlightCream number 1017. The app works very solid, and just as the video demonstrates. I downloaded and tried this, and it immediately did 2 things: bought it, and pinned it to my start page. I like this because it's fun to work with, and it works great as a browser. I'm about *this* close to replacing the IE tile on my front page with SurfCube. SurfCube Browser is by Kinabalu Innovation Limited and is $1.99 and has a free trial. Coming in with another News app is United Nations News by Justin Angel. This is definitely a news aggregator for 'grown ups'... news, photos, videos, and radio broadcsts from the international community all in one very slick app. This is an amazingly well thought-out and complete app. Even better yet, Justin has the code on CodePlex. A very well-done International news aggregator. United Nations News is by Justin Angel and is Free. A few disclaimers: Feel free to write me about your app and tell me about it. While it would be very cool to receive a whole bunch of xap files to review, at this point, for technical reasons, I'm unable to side-load my device. Since I plan on only doing this one day a week (twice if I find time), and only 5, I may never get caught up, so if you send me some info, be patient. Re: games ... remember I'm old... I'm from the era of Colossal Cave and Zork. Duke-Nukem 2D and Captain Comic were awesome. I don't own an XBOX or any other game system, so take game reviews from my perspective -- who knows, it may be refreshing :) I won't pay for an app or game just to try it. If you expect me to test-drive your app, it's going to have to have a Free Trial. I'm still playing with the format, comments are welcome. I decided I should alphabetize the list today... so there's no order implied Let me know what you think of the idea of doing reviews, or the layout/whatever, and Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• Silverlight Cream Top Posted Authors August, 2010 to January, 2011

  - by Dave Campbell

  It's *way* past the first of February, and it's now time to recognize devs that have a large number of posts in Silverlight Cream. Ground Rules I pick what posts are on the blog Only posts that go in the database are included The author has to appear in SC at least 4 of the 6 months considered I averaged the monthly posts and am only showing Authors with an average greater than 1. Here are the Top Posted Authors at Silverlight Cream for August 1, 2010 through January 31, 2011: It is my intention to post a new list sometime shortly after the 1st of every month to recognize the top posted in the previous 6 months, so next up is March 1! Some other metrics for Silverlight Cream: At the time of this posting there are 7304 articles aggregated and searchable by partial Author, partial Title, keywords (in the synopsis), or partial URL. There are also 118 tags by which the articles can be searched. This is an increase of 265 posts over last month. At the time of this posting there are 783 articles tagged wp7dev. This is an increase of 155 posts over last month, or over half of the posts added. Stay in the 'Light!

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• My computer will no longer suspend or shut off when I close the lid

  - by dave

  This is somewhat annoying. I have an old laptop and the screen on it is shot, so now I have an old monitor hooked up and it works fine. Before the upgrade I had it set so that when i closed the lid on the laptop everything would shutdown or suspend, when I lift the lid, everything would come back. Now, however, when i close the lid nothing happens, when i open the lid the screen flashes black and comes back. I have it set so that it should suspend when i close the lid. It's confusing...

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• How do I create my own programming language and a compiler for it

  - by Dave

  I am thorough with programming and have come across languages including BASIC, FORTRAN, COBOL, LISP, LOGO, Java, C++, C, MATLAB, Mathematica, Python, Ruby, Perl, JavaScript, Assembly and so on. I can't understand how people create programming languages and devise compilers for it. I also couldn't understand how people create OS like Windows, Mac, UNIX, DOS and so on. The other thing that is mysterious to me is how people create libraries like OpenGL, OpenCL, OpenCV, Cocoa, MFC and so on. The last thing I am unable to figure out is how scientists devise an assembly language and an assembler for a microprocessor. I would really like to learn all of these stuff and I am 15 years old. I always wanted to be a computer scientist someone like Babbage, Turing, Shannon, or Dennis Ritchie. I have already read Aho's Compiler Design and Tanenbaum's OS concepts book and they all only discuss concepts and code in a high level. They don't go into the details and nuances and how to devise a compiler or operating system. I want a concrete understanding so that I can create one myself and not just an understanding of what a thread, semaphore, process, or parsing is. I asked my brother about all this. He is a SB student in EECS at MIT and hasn't got a clue of how to actually create all these stuff in the real world. All he knows is just an understanding of Compiler Design and OS concepts like the ones that you guys have mentioned (i.e. like Thread, Synchronization, Concurrency, memory management, Lexical Analysis, Intermediate code generation and so on)

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