Search Results

Search found 46009 results on 1841 pages for 'first timer'.

Page 190/1841 | < Previous Page | 186 187 188 189 190 191 192 193 194 195 196 197  | Next Page >

  • Height Map Mapping to "Chunked" Quadrilateralized Spherical Cube

    - by user3684950
    I have been working on a procedural spherical terrain generator for a few months which has a quadtree LOD system. The system splits the six faces of a quadrilateralized spherical cube into smaller "quads" or "patches" as the player approaches those faces. What I can't figure out is how to generate height maps for these patches. To generate the heights I am using a 3D ridged multi fractals algorithm. For now I can only displace the vertices of the patches directly using the output from the ridged multi fractals. I don't understand how I generate height maps that allow the vertices of a terrain patch to be mapped to pixels in the height map. The only thing I can think of is taking each vertex in a patch, plug that into the RMF and take that position and translate into u,v coordinates then determine the pixel position directly from the u,v coordinates and determine the grayscale color based on the height. I feel as if this is the right approach but there are a few other things that may further complicate my problem. First of all I intend to use "height maps" with a pixel resolution of 192x192 while the vertex "resolution" of each terrain patch is only 16x16 - meaning that I don't have any vertices to sample for the RMF for most of the pixels. The main reason the height map resolution is higher so that I can use it to generate a normal map (otherwise the height maps serve little purpose as I can just directly displace vertices as I currently am). I am pretty much following this paper very closely. This is, essentially, the part I am having trouble with. Using the cube-to-sphere mapping and the ridged multifractal algorithm previously described, a normalized height value ([0, 1]) is calculated. Using this height value, the terrain position is calculated and stored in the first three channels of the positionmap (RGB) – this will be used to calculate the normalmap. The fourth channel (A) is used to store the height value itself, to be used in the heightmap. The steps in the first sentence are my primary problem. I don't understand how the pixel positions correspond to positions on the sphere and what positions are sampled for the RMF to generate the pixels if only vertices cannot be used.

    Read the article

  • Unbutu 10.10 (MAVERICK) live cd booting?

    - by D3c3nt Boy
    I am user of window and i had keen to shift on LINUX so i made live cd of UNBUTU 10.10 (MAVERICK) THIS IS MY VERY FIRST TIME TO USE UNBUTU I put cd in cd drive and set bios setup and unbutu cd worked and logo of unbutu appear on screen but suddenly before start up screen it shows this Busy Box v 1.5 (Unbutu 1: 1.15.31 unbutu5) built in shell (ash) enter help for a list of built in commands When i type help and press enter the list of commands appear like below alias break cd chdir command continue echo eval exec export filse getopts hash help let local printf pwd read readonly return set shift source test This is my first time so i have no idea what to do i restart my pc several but it happens every time plz help me. what should i do? Sorry for my

    Read the article

  • sprite animation system height recalculating has some issues

    - by Nicolas Martel
    Basically, the way it works is that it update the frame to show every let's say 24 ticks and every time the frame update, it recalculates the height and width of the new sprite to render so that my gravity logics and stuff works well. But the problem i am having now is a bit hard to explain in words only, therefore i will use this picture to assist me The picture So what i need basically is that if let's say i froze the sprite at the first frame, then unfreeze it and freeze it at the second frame, have the second frame's sprite (let's say it's a prone move) simply stand on the foothold without starting the gravity and when switching back, have the first sprite go back on the foothold like normal without being under the foothold. I had 2 ideas on doing this but I'm not sure it's the most efficient ways to do it so i wanna hear your inputs.

    Read the article

  • Which tool to create a sitemap to plan a future site?

    - by peterpurzelbaum
    I'd like to create a sitemap to plan a future site, and I'm looking for a tool to do it. I'd like to create a list of all articles first. Then a hierachy. Then I'd like to put the articles on several places in the hierachy. I should be able to put one article at different places. I'd like to have the ability to mark the articles in different colors whether they should come into the first version of the website or later.

    Read the article

  • When syncing, removed contacts still show upp (One contacts)

    - by Niklas
    Hi! I just tried out using the Ubuntu One Contacts app for android. First I imported all the contacts from my phone, SIM-card and Google mail account, then I spent quite a while removing duplicates which got imported. Then I tried to sync it for the first time. The strange thing is that I also got all the contacts which I removed from my contacts list on the website. So I have to set "show only contacts with phone numbers" to get all the email adresses I imported from google ealier to not show up, even though I deleted them from the contacts list and have only Ubuntu One contacts showing. Why is that? Thank you!

    Read the article

  • Xubuntu 14.04 will not boot after preseed installation

    - by Christian
    I recently set up Xubuntu 14.04 installation using preseed, and ran into a couple of problems during boot time. At first, right after the installation completed during first boot the system complained about /tmp not being mounted and did not proceed any further. I was able to fix that problem by making an entry for /tmp in /etc/fstab like so: tmpfs /tmp tmpfs optional,nodev,nosuid 0 0 This worked for a while (and still does for workstations that are already running), but newly installed machines are broken. They do not complain like before, but take forever to boot (2h) and it seems the root partition is mounted read only and you cannot do anything useful with the system. Any ideas on what to do? You can find the presseed file here Thanks in advance Update: If I get it to boot once via some magic in rescue mode (like simply mounting the root partition read-write, then resume boot) it will work forever. While this is a workaround, it is no option to do this for every installation.

    Read the article

  • Has MyEclipse implicit breakpoint in debugging mode in class URLClassPath [migrated]

    - by MJM
    I am beginner in MyEclipse IDEA. I using 8.6.1 version of it. My issue is: When I execute my program in debug mode, MyEclipse go to sun.misc.URLClassPath class and I must Resume breakpoint(by pressing F8 key) and continue executing my program. MyEclipse stay in URLClassPath class in following thread stack: 1. URLClassPath$JarLoader.<init>(URL, URLStreamHandler, HashMap) line: 581 2. URLClassPath$JarLoader.ensureOpen() line: 631 3. URLClassPath$JarLoader.getJarFile(URL) line: 641 4. URLClassPath$JarLoader.ensureOpen() line: 631 Note: this event happen when some jar file exist in my project Build-Path but when my application is simple this problem don't make and first breakpoint is my first breakpoint. Why this event happened?

    Read the article

  • Quicktips 1: Windows 7 Libraries; New website

    - by Michael B. McLaughlin
    I’m working on several large posts right now. So in the interim, I’ve decided to do shorter posts that contain something I find very helpful. This is the first. I’ve been using Windows 7 since April 2010. It’s the first OS I’ve ever worked with that I actually enjoy. I’ve used many over the years (KERNAL; PC DOS; MS-DOS 3.x+; Windows 3.0, 3.11, 95, 98, 98 SE, Me, NT 3.51, NT 4, 2000, XP, Vista, 7; various GNU/Linux distros starting with Debian 1.2 – most recently Ubuntu 10.04; ProDOS, Mac OS 9.X, Mac OS X (through 10.4); SunOS, Solaris; AIX, z/OS; OpenVMS). Some were frustrating. Some tolerable. Some were “nice except for…”. OS X actually started out as seemingly “nice” until every single release contained a breaking change to some major API and they then decided to flip-off everyone who had bought a Mac as little as two years earlier with the release of Snow Leopard without PPC support. Windows 7 is the first one that’s just “nice” without any qualifiers. There are so many little features that add up to make it nice. Today’s Quicktip is one of them. Quicktip 1: Create a Library for your Code One thing I particularly like about Windows 7 is the Libraries feature in Explorer. Specifically the fact that you can create custom ones. I used to spend a lot of time opening new Explorer windows and navigating my various Visual Studio projects folders. Custom libraries allowed me to simplify that whole process. I now simply go to my “Code” library and there it all is. Adding a new library is easy. Open an Explorer window. If you aren’t in your Libraries when it opens, navigate to Libraries. Click the “New library” button. Give it a name. Then right click on the new library you created and go to “Properties”. Click the “Include a folder…” button. Choose the folder you want and press “Include folder”. Voilà! If you wish to add more, simply click “Include a folder…” again and repeat. It’s true that this is just a small time saver. But it’s one of those things that just adds a really nice touch. ------------------------ In a separate note, just before Christmas I finally finished and published my new website: http://www.bobtacoindustries.com/ . I waited to post here about it until I found time to incorporate a few things I hadn’t had the time to do when I pushed it out for its “soft open”. Most of them are now done and so my site is now formally open. I have no plans or intentions of moving my blog ( http://blog.bobtacoindustries.com/ points here). I quite like it here, both in terms of the interface and also in terms of the concept (and realization thereof) of pooling geek bloggers to create a pool of knowledge and helpful tips, tricks, techniques, and advice. I created it simply because I felt that it was time to have a website as I venture further into my return to the land of software development. The “For Devs” section should hopefully be useful to developers, particularly the links section. It’s my curated list of sites that I regularly visit to solve problems, to help answer questions on Twitter and the AppHub forums, and to learn new things. I’ll be adding links to it periodically and will be including topic areas as I become acquainted with them enough to form a proper list. WPF will likely be the first topic area added. If there are any links you think I should add to the existing topics, let me know! I warn in advance that I’m less inclined to add blogs; there are simply too many good blogs and I do not want to have hundreds per topic area. So blogs are limited primarily, though not exclusively, to acknowledged experts in the subject area who generally blog regularly about it and who usually are part of the team that develops the product or technology in question. I’m much more amenable to including individual blogs posts in the techniques subcategory in the appropriate topic area. Ultimately, it’s a collection of things I find interesting and helpful. So please no hard feelings if I don’t add a link you think is awesome. I may well think it’s awesome too, but conclude that it doesn’t fit with my goals for the dev links area.

    Read the article

  • Making your ASP.NET/HTML Websites Indic aware &ndash; accepting Tamil, Telugu, Kannada, Hindi and ot

    - by Harish Ranganathan
    Its been a month since I wrote my last post.  Much of work has been happening around planning for Tech Ed India, the upcoming Virtual TechDays this week as well as our Developer content at the Great Indian Developer Summit 2010.  Its going to be one exciting period starting this week and I am glad I would be able to meet a lot of folks who have written to me personally that they would like to catch up at Tech Ed India. For now, I had a chance to meet the Microsoft India Development Centre team that worked on the Microsoft Indic Language Input Tool (erstwhile Akshara). The team updated me that they have also released the scripts  so that the Indic input feature can be encapsulated into your own websites.  For example, if you are having a web page where you collect user information, you can pretty much make your site indic aware i.e. accept inputs in Tamil, Telugu, Kannada, Hindi etc.,  All you would need to include would be a bunch of scripts onto your web pages and you are ready to make it, like I said, “indic aware” I have built a sample web page that accepts First Name, Last Name, Address and an additional field.  When it comes to accepting indic, sometimes, you may want to avoid the indic input in certain fields and accept it in English.  You can specify the MicrosoftILITWebAttach="false" attribute to the Text Boxes and Text Areas (TextMode=”Multiline” in ASP.NET) so that the particular field automatically switches over to English input.  Similarly, the moment you specify that the TextMode=”Password” to make it as a password field, it automatically ignores all indic recognition and shows the masked dots for the words entered. Note that, this is, when we are going for the Opt-out mode, where we are specifying that by default all the input controls would need indic awareness and we would specify for those controls where it is not required.  The other mode is Opt-in mode where you would need to add a different property to the script definition i.e. attachMode=”optin” .  When we do this, we need to explicitly add the MicrosoftILITWebAttach="true" attribute for every control where we need indic input. I have created a sample web page which accepts First Name, Last Name, Address and an additional input field to demonstrate the “Opt-out”.   You can copy paste this into any of your web pages to check it <form id="form1" runat="server">     <!-- Microsoft Indic Language Input Tool embed code --> <input type="hidden" id="MicrosoftILITWebEmbedInfo" attachMode="optout" value="" /> <script type="text/javascript" src="http://ilit.microsoft.com/bookmarklet/script/Tamil.js" defer="defer"></script>     <div>     <h2>         Welcome to the Registration Page     </h2>     <p>         First Name: <asp:TextBox runat="server" ID="txtFirstName" />         <br />         <br />         Last Name: <asp:TextBox runat="server" ID="txtLastName" />         <br />         <br />         Password:         <asp:TextBox runat="server" ID="txtPassword" TextMode="Password" />         <br />         <br />         Address: <asp:TextBox runat="server" ID="txtAddress" TextMode="MultiLine" Height="100" Width="200" />         <br />         <br />         English Text: <asp:TextBox ID="txtEnglishText" runat="server" MicrosoftILITWebAttach="false" />     </p>     <p>         <!-- Microsoft Indic Language Input Tool attribution image link --> <a style="text-decoration: none" href="http://go.microsoft.com/fwlink/?LinkID=184205&clcid=0x409"><img style="border: 0px" alt="Transliteration by Microsoft" src="http://ilit.microsoft.com/bookmarklet/images/attribution.png"></a>     </p>     </div>     </form> If you note the code snippet above, I have included the scripts in the top with the attachMode set to “optout” and for the last TextBox, I have mentioned the MicrosoftILITWebAttach="false” attribute to make it accept English input.   Additionally, you also need to add the “Microsoft Indic Language Input Tool attribution image” to your web page as a courtesy to the team that developed this feature.  It would basically add a image saying “Transliteration by Microsoft” similar to a Copy Right image.  You can see the screen shot below where I have typed it in Tamil.  In that you will notice that the password field behaves as expected and the last field accepts English Text.  You can also notice the icon that comes in the first textbox that indicates that, the field is going to accept indic text.   This sample is using Tamil, but you can pretty much do it for Hindi, Telugu, Kannada, Marathi, Bengali etc.,   The website for getting the Indic script and other instructions is http://specials.msn.co.in/ilit/WebEmbed.aspx?language=Tamil You can replace the querystring value “Tamil” to other languages as mentioned above to get the respective script. This also works for plain HTML based websites and doesn’t necessarily need you to use ASP.NET to achieve the functionality. Note that, this form is not completely localized.  This is transliterated.  You can add label controls for FirstName, LastName indication etc., and use the Visual Studio tools to localize and get those values from resource files.  In the resource files, you can enter the text in different languages to make this a truly localized page.  If you just want to download the Indic Tool Desktop version (that can be used for typing in Word, Excel, pretty much any input area), you can download it from http://specials.msn.co.in/ilit/  In the same page, there is also a web version where you can type and get text then and there if you dont want to install the desktop version. So, go ahead, download / use them in your websites and enjoy the power of Indic. Cheers !!!

    Read the article

  • Local Entities with NHibernate

    - by Ricardo Peres
    You may know that Entity Framework Code First has a nice property called Local which lets you iterate through all the entities loaded by the current context (first level cache). This comes handy at times, so I decided to check if it would be difficult to have it on NHibernate. It turned out it is not, so here it is! Another nice addition to an NHibernate toolbox! public static class SessionExtensions { public static IEnumerable<T> Local<T>(this ISession session) { ISessionImplementor impl = session.GetSessionImplementation(); IPersistenceContext pc = impl.PersistenceContext; foreach (Object key in pc.EntityEntries.Keys) { if (key is T) { yield return ((T) key); } } } } //simple usage IEnumerable<Post> localPosts = session.Local<Post>(); SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

    Read the article

  • unable to mount internal disk mount exited with exit code 13

    - by Masri
    My Ubuntu get into error when I try to mount one of my internal disks and it gives this error message: Error mounting: mount exited with exit code 13: $MFTMirr does not match $MFT (record 3). Failed to mount '/dev/sda7': Input/output error NTFS is either inconsistent, or there is a hardware fault, or it's a SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows then reboot into Windows twice. The usage of the /f parameter is very important! If the device is a SoftRAID/FakeRAID then first activate it and mount a different device under the /dev/mapper/ directory, (e.g. /dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation for more details. pls advise how to solve above error ,Many thanks to you in advance.

    Read the article

  • Ubuntu 12.04.3 Graphics Issues: Broken Pipes, Reinstalled Xorg and Bumblebee

    - by user190488
    It seems I have a problem, and am only making it worse by following what I find online. I have a new Asus N550JV-D71 (not sure about the part after the dash, though I definitely know it includes 71). I decided to downgrade Windows 8 to 7, then dual boot Ubuntu 12.04 with it (there were issues with Windows 8, and I had a Windows 7 disk handy). It did work and, after installing Bumblebee in tty (because it wouldn't boot when it was first installed), it worked marvelously for a little less than a week. However, I restarted it last night and got the Could not write bytes: Broken pipes error. (I see it's a very common error, but I've looked at the majority of the suggested Similar Questions already.) I followed what I could find online, followed those instructions (making sure to not install any sort of graphics drivers other than what Bumblebee provides), and it just seems to go further and further downhill. I'm afraid I didn't write the exact steps to get to this point (it was late by the time I gave up the night before), but it involved reinstalling lightdm, xorg (and xserver?), and Bumblebee. I then changed the Bumblebee.conf file so that Device=nvidia. I'm pretty new to Linux in general (I've used it since 10.04, but I hadn't had issues up until this computer, so it let me stay a newbie), so I'm not exactly sure what log files to look at to find the errors to look up. However, I did look at lshw and noticed that displays was marked as unassigned. Also, if I try to start lightdm using the command line, it always stops at Stopping Mount network filesystems. I should note that there isn't an xorg.conf file, and no .Xauthority. I would really, really prefer not to reinstall 12.04 if possible. I managed to get grub to display only a short time ago, and I can't boot to the dvd drive unless I go into the BIOS settings and manually change the boot order (that was an issue from the beginning, before the Ubuntu install), and getting into those settings often means rebooting several times due to the fact that the window to get to it is extremely small. I have most of what I need backed up, however, in case it does get to that point. If I really have to, I can just use the latest Ubuntu version instead of the LTS, but the reason I chose 12.04 in the first place is because I need something stable-ish, and Windows isn't suitable to what I need to do. I should note that the reason I restarted last night in the first place was that it wasn't charging the battery, and the wifi kept on going out. Hardware: Nvidia GeForce GT 750M Intel HD graphics 4600

    Read the article

  • Internet Explorer 10 aborting some stylesheets

    - by Joe
    Strange problem exhibited only with IE10 on Windows 8. No other IE version, no other OS version. Some stylesheets are aborted, apparently in transport, intermittently. This seems to happen when there are three <link> tags in sequence. The tags are correctly specified and are being served from Amazon S3 over HTTPS. The first two items abort when (or prior to) loading. Altering the order of the items appears to make the first two items abort in all cases. This problem is intermittent, and different people can reproduce with differing success. I have seen a lot of conjecture about this on the web but no solution.

    Read the article

  • The clean coders videos [closed]

    - by Sebastian
    As many others, I have been reading Uncle Bob Martins books. More specifically, clean code and then "the clean coder". Now, over the last year he has been producing "code casts" that you can buy for ~20USD a piece. I bought the first episode sometime in mid 2011 and wasnt that impressed, as I really learned nothing new after reading his books. Last night I bought the first episode of test driven development with more or less the same result as last time. Now tonight I gave it one more go and bought TDD part 2 and this one was, IMO, really good. With this post I would like to tip others about his videos and would also like to know what others think. BR Sebastian

    Read the article

  • JavaOne - Java SE Embedded Booth - Servergy Micro Server

    - by David Clack
    Hi All,  So it's been awhile, I've been working with all the ARM and Power Architecture partners we have now on testing Java SE Embedded. We will have a Java SE Embedded for ARM and PPC at Java One next week, I'll be bringing in some of the great ARM and PPC systems to demonstrate.  The first system I'd like to tell you about is a really cool 8 core Power Architecture Micro Server from a company in Dallas called Servergy. Java One will be it's first public outing, Bill Mapp the CEO will be doing a talk at the Java Embedded @ JavaOne conference in the Hotel Nikko, right next door to the JavaOne show in the Hilton. To read more about Servergy https://www.linux.com/news/enterprise/cloud-computing/641488-linux-based-servergy-advances-data-center-efficiency http://www.servergy.com/ If you are registered at JavaOne you can come over to the Java Embedded @ JavaOne for $100 Come see us in booth 5605 See you there Dave

    Read the article

  • A particular url on a website suddenly disappeared from google search results - why?

    - by Ragavendran Ramesh
    I have a website which had a particular page url that was indexed in google search results - in the first 10 results. Suddenly it disappeared. Now that page is not even in the first 100 results. What would be the reason? I am feeling that the page has be spammed by our competitors. Is it possible to avoid that, or can I find if that page has been spammed or not? Is it possible to find the particular page in a website is spam or malicious?

    Read the article

  • Split vector vs matrix notation for transformation

    - by seahorse
    Some rendering engines like Ogre prefer to use a individual vector based notation for transformations like the following Split vector notation: Net Transformation is represented by Scale vector = sx, sy, sz Transformation vector = tx, ty, tz Rotation Quaternion Vector = w,x,y,z Matrix notation: There are other engines which simply use a net combined transformation matrix. What are the advantages of the first notation over the second? Also for animation interpolation does it work in the first notation that we interpolate across the individual components and use the interpolated parts to get the net transformation? Is this another advantage?

    Read the article

  • .pam_environment in kerberized nfs4 home directory

    - by Paul Stoever
    How can I get pam_env to read the user's .pam_environment file, if the user's file is located in a kerberized NFS4 mount? The file and directory permissions for the .pam_environment file are set in a way, that allows the local root to read the file. Reading .pam_environment only fails on the first login. Subsequent logins successfully read the file. The client uses Ubuntu 12.04 Desktop, NFS/Kerberos server is 12.04 Server. The Kerberos/NFS4 stuff works with exception of this. From /var/log/auth for first login: ... lightdm: pam_krb5(lightdm:auth): user USERNAME authenticated as USERNAME@REALM lightdm: pam_unix(lightdm:session): session closed for user lightdm lightdm: pam_env(lightdm:setcred): Unable to open config file: USERHOME/.pam_environment: Permission denied lightdm: pam_env(lightdm:setcred): Unable to open config file: USERHOME/.pam_environment: Permission denied lightdm: pam_unix(lightdm:session): session opened for user USERNAME by (uid=0) ...

    Read the article

  • DTracing TCP congestion control

    - by user12820842
    In a previous post, I showed how we can use DTrace to probe TCP receive and send window events. TCP receive and send windows are in effect both about flow-controlling how much data can be received - the receive window reflects how much data the local TCP is prepared to receive, while the send window simply reflects the size of the receive window of the peer TCP. Both then represent flow control as imposed by the receiver. However, consider that without the sender imposing flow control, and a slow link to a peer, TCP will simply fill up it's window with sent segments. Dealing with multiple TCP implementations filling their peer TCP's receive windows in this manner, busy intermediate routers may drop some of these segments, leading to timeout and retransmission, which may again lead to drops. This is termed congestion, and TCP has multiple congestion control strategies. We can see that in this example, we need to have some way of adjusting how much data we send depending on how quickly we receive acknowledgement - if we get ACKs quickly, we can safely send more segments, but if acknowledgements come slowly, we should proceed with more caution. More generally, we need to implement flow control on the send side also. Slow Start and Congestion Avoidance From RFC2581, let's examine the relevant variables: "The congestion window (cwnd) is a sender-side limit on the amount of data the sender can transmit into the network before receiving an acknowledgment (ACK). Another state variable, the slow start threshold (ssthresh), is used to determine whether the slow start or congestion avoidance algorithm is used to control data transmission" Slow start is used to probe the network's ability to handle transmission bursts both when a connection is first created and when retransmission timers fire. The latter case is important, as the fact that we have effectively lost TCP data acts as a motivator for re-probing how much data the network can handle from the sending TCP. The congestion window (cwnd) is initialized to a relatively small value, generally a low multiple of the sending maximum segment size. When slow start kicks in, we will only send that number of bytes before waiting for acknowledgement. When acknowledgements are received, the congestion window is increased in size until cwnd reaches the slow start threshold ssthresh value. For most congestion control algorithms the window increases exponentially under slow start, assuming we receive acknowledgements. We send 1 segment, receive an ACK, increase the cwnd by 1 MSS to 2*MSS, send 2 segments, receive 2 ACKs, increase the cwnd by 2*MSS to 4*MSS, send 4 segments etc. When the congestion window exceeds the slow start threshold, congestion avoidance is used instead of slow start. During congestion avoidance, the congestion window is generally updated by one MSS for each round-trip-time as opposed to each ACK, and so cwnd growth is linear instead of exponential (we may receive multiple ACKs within a single RTT). This continues until congestion is detected. If a retransmit timer fires, congestion is assumed and the ssthresh value is reset. It is reset to a fraction of the number of bytes outstanding (unacknowledged) in the network. At the same time the congestion window is reset to a single max segment size. Thus, we initiate slow start until we start receiving acknowledgements again, at which point we can eventually flip over to congestion avoidance when cwnd ssthresh. Congestion control algorithms differ most in how they handle the other indication of congestion - duplicate ACKs. A duplicate ACK is a strong indication that data has been lost, since they often come from a receiver explicitly asking for a retransmission. In some cases, a duplicate ACK may be generated at the receiver as a result of packets arriving out-of-order, so it is sensible to wait for multiple duplicate ACKs before assuming packet loss rather than out-of-order delivery. This is termed fast retransmit (i.e. retransmit without waiting for the retransmission timer to expire). Note that on Oracle Solaris 11, the congestion control method used can be customized. See here for more details. In general, 3 or more duplicate ACKs indicate packet loss and should trigger fast retransmit . It's best not to revert to slow start in this case, as the fact that the receiver knew it was missing data suggests it has received data with a higher sequence number, so we know traffic is still flowing. Falling back to slow start would be excessive therefore, so fast recovery is used instead. Observing slow start and congestion avoidance The following script counts TCP segments sent when under slow start (cwnd ssthresh). #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::connect-request / start[args[1]-cs_cid] == 0/ { start[args[1]-cs_cid] = 1; } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd tcps_cwnd_ssthresh / { @c["Slow start", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd args[3]-tcps_cwnd_ssthresh / { @c["Congestion avoidance", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } As we can see the script only works on connections initiated since it is started (using the start[] associative array with the connection ID as index to set whether it's a new connection (start[cid] = 1). From there we simply differentiate send events where cwnd ssthresh (congestion avoidance). Here's the output taken when I accessed a YouTube video (where rport is 80) and from an FTP session where I put a large file onto a remote system. # dtrace -s tcp_slow_start.d ^C ALGORITHM RADDR RPORT #SEG Slow start 10.153.125.222 20 6 Slow start 138.3.237.7 80 14 Slow start 10.153.125.222 21 18 Congestion avoidance 10.153.125.222 20 1164 We see that in the case of the YouTube video, slow start was exclusively used. Most of the segments we sent in that case were likely ACKs. Compare this case - where 14 segments were sent using slow start - to the FTP case, where only 6 segments were sent before we switched to congestion avoidance for 1164 segments. In the case of the FTP session, the FTP data on port 20 was predominantly sent with congestion avoidance in operation, while the FTP session relied exclusively on slow start. For the default congestion control algorithm - "newreno" - on Solaris 11, slow start will increase the cwnd by 1 MSS for every acknowledgement received, and by 1 MSS for each RTT in congestion avoidance mode. Different pluggable congestion control algorithms operate slightly differently. For example "highspeed" will update the slow start cwnd by the number of bytes ACKed rather than the MSS. And to finish, here's a neat oneliner to visually display the distribution of congestion window values for all TCP connections to a given remote port using a quantization. In this example, only port 80 is in use and we see the majority of cwnd values for that port are in the 4096-8191 range. # dtrace -n 'tcp:::send { @q[args[4]-tcp_dport] = quantize(args[3]-tcps_cwnd); }' dtrace: description 'tcp:::send ' matched 10 probes ^C 80 value ------------- Distribution ------------- count -1 | 0 0 |@@@@@@ 5 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 0 512 | 0 1024 | 0 2048 |@@@@@@@@@ 8 4096 |@@@@@@@@@@@@@@@@@@@@@@@@@@ 23 8192 | 0

    Read the article

  • SQL2K8R2: StreamInsight changes at RTM: Hopping Windows

    - by Greg Low
    We've been working on updating our demos and samples for the RTM changes of StreamInsight. I'll detail these as I come across them. The first is that there is a change to the HoppingWindow. The first two parameters are the same in the constructor but the third parameter is now required. It is the HoppingWindowOutputPolicy. Currently, there is only a single option for this which is ClipToWindowEnd. So you can create a HoppingWindow like this: var queryOutput = from w in input.HoppingWindow ( TimeSpan...(read more)

    Read the article

  • Best place to request Ubuntu for a minor improvement (In Unity dash search)

    - by mac
    Which is the best place to request Ubuntu for a minor improvement? My request feature is this : In Ubuntu dash when I search for "Upd" it gives me update manager and some other files. Now when I click enter by default the first entry will be selected. Can we make this a slightly better experience by highlighting the first item in search results which will be selected by default if we press enter - Just like in Gnome shell Search for upd in unity dash Search for upd in gnome-shell If you notice, update manager is highlighted by default in gnome shell and appears more intuitive. Can we implement the same in Unity ? Sorry for posting this in askubuntu. I just wanted to know which is the best place to discuss this. Thanks

    Read the article

  • 2D water with dynamic waves

    - by user1103457
    New Super Mario Bros has really cool 2D water that I'd like to learn how to create. Here's a video showing it. When something hits the water, it creates a wave. There are also constant "background" waves. You can get a good look at the constant waves just after 00:50 when the camera isn't moving. I assume the splashes in NSMB work as in the first part of this tutorial. But in NSMB the water also has constant waves on the surface, and the splashes look very different. Another difference is that in the tutorial, if you create a splash, it first creates a deep "hole" in the water at the origin of the splash. In new super mario bros this hole is absent or much smaller. I am referring to the splashes that the player creates when jumping in and out of the water. How do they create the constant waves and the splashes? I am especially interested in the splashes, and how they work together with the constant waves. I am programming in XNA. I've tried this myself, but couldn't really get it all to work well together. Bonus questions: How do they create the light spots just under the surface of the waves and how do they texture the deeper parts of the water? This is the first time I try to create water like this. EDIT: I assume the constant waves are created using a sine function. The splashes are probably created in a way like in the tutorial. (But they are not the same, so I am still interested in how to make this kind of splashes) But I have a lot of trouble combining those things. I know I can use the sine function to set the height of a specific watercolumn but the splashes are using the speed, to determine the new height. I can't figure out how to combine those. Not that I am not asking how the developers of new super mario bros did this exactly. I am just interested in ways to recreate an effect like it. This week I have an examweek so I don't have time to work on the code. After this week I will spend a lot of time on it. But I am constantly thinking about it, so that's why I will be checking comments etc. I just won't be looking at the code since it might be too time-consuming.

    Read the article

  • Moving one site in Webmaster Tools to more then one site

    - by Towhid
    I have a Question and Answer site about immigration. now I divided it into 2 sites: mysite.co.uk about immigration to UK mysite.com with sub domains for every country, Like: australia.mysite.com , sweden.mysite.com , ... now I had moved All the content from my first site into .co.uk and .com site and it's sub domains to fill theme. I now that Google will detect my new 2 sites as duplicate of first on and it is very bad for SEO. and I don't think Google webmaster tools has a tool for it. so Please Guide me how to fix this problem.

    Read the article

  • What is the best idea to put available OS (linux) and Web application to client?

    - by Fernando Costa
    After a year programming a web based business management system, I got my idea divided into two differents ways to do what I'm doing... I will try to explain in follow lines: First I will describe my enviroment: Webserver: apache, ngynx Programming Language: PHP, Shell Script, Java Script, SQL Database: Mysql Operating System: Linux, UNIX (All Distros) (If manually configured works on windows) Authentication Server: FreeRadius First situation I have my application running on this enviroment that I had just described before, as my application is a SaaS app, then I have my own server to run it all and customers pay to use it as a service accessed by webbrowser. Second Situation The same as before but with one big difference, everything (environment) is installed in the customer, then I need to cryptography all my codes (It includes PHP and Shell Scripts). I think this situation is most difficulty, but I would like to hear it from different points of view.

    Read the article

< Previous Page | 186 187 188 189 190 191 192 193 194 195 196 197  | Next Page >