Search Results

Search found 6104 results on 245 pages for 'fast esp'.

Page 51/245 | < Previous Page | 47 48 49 50 51 52 53 54 55 56 57 58  | Next Page >

  • Friday Fun: 3 Slices

    - by Asian Angel
    Your weekend is almost here, so why not get an early start on the fun with a quick bit of gaming goodness? In this week’s game your powers of division will be put to the test as you seek to clear each level of red box material using a limited number of slices. How to Make the Kindle Fire Silk Browser *Actually* Fast! Amazon’s New Kindle Fire Tablet: the How-To Geek Review HTG Explains: How Hackers Take Over Web Sites with SQL Injection / DDoS

    Read the article

  • Google I/O 2010 - Integrate apps w/ Google Apps Marketplace

    Google I/O 2010 - Integrate apps w/ Google Apps Marketplace Google I/O 2010 - Integrating your app with the Google Apps Marketplace: Navigation, SSO, Data APIs and manifests Enterprise 201 Ryan Boyd, Steve Bazyl In this fast-paced, demo-focused session, you'll learn how to build, integrate, and sell a web app on the Google Apps Marketplace. We'll go end-to-end in 40 minutes with time left for Q&A. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 5 0 ratings Time: 59:45 More in Science & Technology

    Read the article

  • Slow internet connection with mobile broadband

    - by Prasad
    I'm using a Huawei 156g USB stick to connect to the internet. In windows it reacts lightning fast and loads pages faster than my Ubuntu 10.10 does, It's not the connection type (HSDPA, WCDMA or gsm) it takes more time to connect, download speed seems okay (But not full speed i think) what is the matter with it? do I need to install some kind of drivers for it? I'm not behind a proxy. please help, I just searched around ask Ubuntu and nothing matched my problem :-(

    Read the article

  • Can Flash games packed for iOS and other mobile devices achieve reasonable performance?

    - by puppybeard
    I was thinking of developing a game in Flash, as a hobby/educational project. However, I was hoping I could make it run on a smartphone, but a friend who develops in Flash says that in their experience things will move really slow on the likes of an iPad when the Flash packager is used. So slowly that you can't use it commercially for fast-moving games. Has anyone else experienced this slowness? Is there a way around it or is the technology just not there yet?

    Read the article

  • Problem by installing Java

    - by Shagun
    Yesterday night I was trying to download Java as per instructions given on http://developer.android.com/ .But I messed up somewhere and had to give up the thing. But since morning when ever I try to install or remove some thing I get the following response http://paste.ubuntu.com/1198084/ Please help fast. I am a newbie in android development and have to submit an app within 5 days from now for a project. And I need my linux machine working fine for that.

    Read the article

  • Google I/O 2010 - Using Google Chrome Frame

    Google I/O 2010 - Using Google Chrome Frame Google I/O 2010 - Using Google Chrome Frame Chrome 201 Alex Russell Google Chrome Frame brings the HTML5 platform and fast Javascript performance to IE6, 7 & 8. This session will cover the latest on Google Chrome Frame, what it can do for you and your customers, how it can be used, and a sneak peak into what's planned next. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 4 0 ratings Time: 50:16 More in Science & Technology

    Read the article

  • SEO and SEM in China

    With the advent of internet, the Chinese people are shopping and learning new ways, thus the ecommerce sector is evolving at fast pace in order to meet the needs and requirements of the wide variety of clientele. Today, a large number of Chinese internet users like to shop online but have very little idea about China SEO strategies involved in the process of internet shopping.

    Read the article

  • Ask HTG: LAN-to-LAN Messaging in Windows 7, Multi-Monitor Full Screen Video, and Alternative File Copiers

    - by Jason Fitzpatrick
    Once a week we roundup some of the answers we’ve sent out to reader questions and share them with everyone. This week we’re looking at inter-LAN messaging with Windows 7, multi-monitor full screen video, and alternative Windows file copiers. How to See What Web Sites Your Computer is Secretly Connecting To HTG Explains: When Do You Need to Update Your Drivers? How to Make the Kindle Fire Silk Browser *Actually* Fast!

    Read the article

  • Google I/O 2010 - Sell your app on the Google Apps Marketplace

    Google I/O 2010 - Sell your app on the Google Apps Marketplace Google I/O 2010 - Reach new customers fast: Learn how to sell your cloud app on the Google Apps Marketplace Enterprise 201 Scott McMullan, Jay Simmons (Atlassian), Chuck Dietrich (Sliderocket), Amit Kulkarni (Manymoon) In this introductory session we'll provide an overview of the Google Apps Marketplace and learn product and marketing best practices directly from 3 Marketplace ISVs. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 12 0 ratings Time: 56:42 More in Science & Technology

    Read the article

  • 30 Great Photoshop Tips and Tricks to Help Your Computer Graphic Skills

    - by Lori Kaufman
    Photoshop is a powerful, but complex, graphics program that can be difficult to learn and frustrating to use. We have published many articles about tips and tricks for using Photoshop and how to fix annoying issues you may encounter. This article compiles 30 of the best tips and tricks we have documented to help you get the most out of Photoshop. How to Make the Kindle Fire Silk Browser *Actually* Fast! Amazon’s New Kindle Fire Tablet: the How-To Geek Review HTG Explains: How Hackers Take Over Web Sites with SQL Injection / DDoS

    Read the article

  • SQL Server 2008 R2 Express Edition - a treat for small scale businesses

    - by ssqa.net
    SQL Server Express edition is a light-weight software within SQL Server arena, it is classed as database platform that makes it easy to develop data-driven applications that are rich in capability, offer enhanced storage security, and are fast to deploy. Also the SQL Server 2008 Express with Advanced Services is an edition of same flock that includes a new graphical management tool, features for reporting, and advanced text-based search capabilities. You can add the GUI capabilities for management...(read more)

    Read the article

  • From the Tips Box: iPad Interface Emulation for Windows, Easy Access iPhone Flashlight, and Kindle Collection Management

    - by Jason Fitzpatrick
    Once a week we round up some of the great reader tips to share. Today we’re looking at an iPad interface emulator for Windows, a fast-access flashlight app for the iPhone, and a Windows-based way to organize Kindle collections. Use Amazon’s Barcode Scanner to Easily Buy Anything from Your Phone How To Migrate Windows 7 to a Solid State Drive Follow How-To Geek on Google+

    Read the article

  • An Interview with Amazon Web Services

    A short interview with Sundar Raghavan of Amazon Web Services about SQL Server and their support and offerings of cloud data services. NEW! Deployment Manager Early Access ReleaseDeploy SQL Server changes and .NET applications fast, frequently, and without fuss, using Deployment Manager, the new tool from Red Gate. Try the Early Access Release to get a 20% discount on Version 1. Download the Early Access Release.

    Read the article

  • Wireless acting weird ubuntu 12.04 LTS

    - by Philip Yeldhos
    I'm kinda new here, so please bear with me. My wireless driver is acting very weird. It shows my router's name, but when it is connecting (after entering the correct password), the icon on the tray is like, refreshing every once in a second, while showing the animation that it is connecting. And after a few seconds, error message come up saying that wireless network is disconnected. I installed the drive through "additional drivers". What info do you need? Somebody please help. philip@philip-HP-Mini-110-3100:~$ sudo iwconfig lo no wireless extensions. eth1 IEEE 802.11 ESSID:"" Mode:Managed Frequency:2.472 GHz Access Point: Not-Associated Bit Rate:72 Mb/s Tx-Power:24 dBm Retry min limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=5/5 Signal level=0 dBm Noise level=-96 dBm Rx invalid nwid:0 Rx invalid crypt:11 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0 eth0 no wireless extensions. here's what lspci -v gave me: 02:00.0 Network controller: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller (rev 01) Subsystem: Hewlett-Packard Company Device 1483 Flags: bus master, fast devsel, latency 0, IRQ 17 Memory at 52000000 (64-bit, non-prefetchable) [size=16K] Capabilities: [40] Power Management version 3 Capabilities: [58] Vendor Specific Information: Len=78 <?> Capabilities: [48] MSI: Enable- Count=1/1 Maskable- 64bit+ Capabilities: [d0] Express Endpoint, MSI 00 Capabilities: [100] Advanced Error Reporting Capabilities: [13c] Virtual Channel Capabilities: [160] Device Serial Number 00-00-82-ff-ff-3f-e0-2a Capabilities: [16c] Power Budgeting <?> Kernel driver in use: wl Kernel modules: wl, bcma, brcmsmac okay, i removed the driver additional drivers gave me. now, this is what has happened: lsmod gave me: philip@philip-HP-Mini-110-3100:~$ lsmod | grep brc brcmsmac 540875 0 mac80211 436455 1 brcmsmac brcmutil 14675 1 brcmsmac cfg80211 178679 2 brcmsmac,mac80211 crc8 12781 1 brcmsmac cordic 12487 1 brcmsmac and iwconfig gave me: philip@philip-HP-Mini-110-3100:~$ iwconfig lo no wireless extensions. wlan0 IEEE 802.11bgn ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=19 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off eth0 no wireless extensions. and lspci -v gave me: 02:00.0 Network controller: Broadcom Corporation BCM4313 802.11b/g/n Wireless LAN Controller (rev 01) Subsystem: Hewlett-Packard Company Device 1483 Flags: bus master, fast devsel, latency 0, IRQ 17 Memory at 52000000 (64-bit, non-prefetchable) [size=16K] Capabilities: <access denied> Kernel driver in use: brcmsmac Kernel modules: bcma, brcmsmac

    Read the article

  • Stay Connected To Friends With Free SMS

    Online SMSs have received mass acceptance today. Though it is distinct in many ways from a mobile phone, it has its own advantages. In today?s fast paced life, people are left with really less time... [Author: Pooja Singh - Computers and Internet - March 29, 2010]

    Read the article

  • Dependency Checker/ Installer With Java/Ant

    - by jsn
    I need some kind of software to easily roll out code on new servers. I use Apache Ant for builds. However, say I want to set-up a new server fast and my Java program depends on GhostScript, if there any software that can automatically check the computer for it (and then maybe the PATH) and add it if is not there? I have already looked at Maven and Apache Ivy, however, I think these are only for .jar files (from what I saw). Thanks for any help.

    Read the article

  • Unable to access other Volume in Vaio E series

    - by Rahul Ravi Kumar Shah
    Error mounting /dev/sda6 at /media/ravi/New Volume: mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,dmask=0077,fmask=0177" "/dev/sda6" "/media/ravi/New Volume" Exited with: non-zero exit status 14: The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Failed to mount '/dev/sda6': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.

    Read the article

  • TomEE Integration in NetBeans Next

    - by Geertjan
    At JavaOne 2013, there was a lot of buzz around the TomEE server, e.g., many Tweets, nice party, and a new TomEE consulting company. For those tracking TomEE developments, it is interesting to note that recently the NetBeans IDE development builds have had added to them... TomEE support. Note: The TomEE support described here is not in NetBeans IDE 7.4, but in development builds for the next release of NetBeans IDE.For example, with NetBeans IDE development builds you're able to: register TomEE as a server in the Services window (TomEE has several distributions, e.g., one can use the "with JAX-RS" one, for example) create a Java EE 6 web project (e.g., Maven based) against this server create JPA entities from database create JAX-RS classes from JPA entities create JSF pages from JPA entities the IDE lets you create a new data source for TomEE and deploy it to the server the IDE figures out the components that are already packaged in TomEE, and the fact that (unlike with regular Tomcat), it does not need to package any components such as JSF implementation, persistence provider, or JAX-RS runtime, so that the resulting WAR file is very small the IDE can also do "deploy on save" with TomEE, so that your development cycle is very fast Adam Bien blogged about how he set up TomEE sometime ago, here. The official support in NetBeans IDE will be much more tightly integrated, simplifying the steps Adam describes. For example, the IDE does step 2 from Adam's blog for you, i.e., it sets up TomEE deployment roles. Moreover, it knows about all the technologies included in TomEE so that it can optimize the packaging; it knows about TomEE's persistence setup; it can work with TomEE data sources, etc. Below you see a Maven-based Java EE 6 PrimeFaces application (all entities and JSF pages generated from a database) deployed to TomEE in NetBeans IDE: And here's the management console for configuring and finetuning TomEE in NetBeans IDE: When I tried out the NetBeans IDE development build and TomEE, to see how everything fits together, I was surprised at how fast TomEE started up. Not sure what they did to it, but seems like a server on steroids. And setting it up in NetBeans IDE was trivial. Add the simple set up of TomEE in NetBeans IDE to the many benefits that the widely praised out of the box NetBeans Maven tools make possible, together with the fact that not one single plugin had to be installed to get everything you see described here up and running... and you have a really powerful combination of dev tools, all for free.

    Read the article

  • Building an Infrastructure Cloud with Oracle VM for x86 + Enterprise Manager 12c

    - by Richard Rotter
    Cloud Computing? Everyone is talking about Cloud these days. Everyone is explaining how the cloud will help you to bring your service up and running very fast, secure and with little effort. You can find these kinds of presentations at almost every event around the globe. But what is really behind all this stuff? Is it really so simple? And the answer is: Yes it is! With the Oracle SW Stack it is! In this post, I will try to bring this down to earth, demonstrating how easy it could be to build a cloud infrastructure with Oracle's solution for cloud computing.But let me cover some basics first: How fast can you build a cloud?How elastic is your cloud so you can provide new services on demand? How much effort does it take to monitor and operate your Cloud Infrastructure in order to meet your SLAs?How easy is it to chargeback for your services provided? These are the critical success factors of Cloud Computing. And Oracle has an answer to all those questions. By using Oracle VM for X86 in combination with Enterprise Manager 12c you can build and control your cloud environment very fast and easy. What are the fundamental building blocks for your cloud? Oracle Cloud Building Blocks #1 Hardware Surprise, surprise. Even the cloud needs to run somewhere, hence you will need hardware. This HW normally consists of servers, storage and networking. But Oracles goes beyond that. There are Optimized Solutions available for your cloud infrastructure. This is a cookbook to build your HW cloud platform. For example, building your cloud infrastructure with blades and our network infrastructure will reduce complexity in your datacenter (Blades with switch network modules, splitter cables to reduce the amount of cables, TOR (Top Of the Rack) switches which are building the interface to your infrastructure environment. Reducing complexity even in the cabling will help you to manage your environment more efficient and with less risk. Of course, our engineered systems fit into the cloud perfectly too. Although they are considered as a PaaS themselves, having the database SW (for Exadata) and the application development environment (for Exalogic) already deployed on them, in general they are ideal systems to enable you building your own cloud and PaaS infrastructure. #2 Virtualization The next missing link in the cloud setup is virtualization. For me personally, it's one of the most hidden "secret", that oracle can provide you with a complete virtualization stack in terms of a hypervisor on both architectures: X86 and Sparc CPUs. There is Oracle VM for X86 and Oracle VM for Sparc available at no additional  license costs if your are running this virtualization stack on top of Oracle HW (and with Oracle Premier Support for HW). This completes the virtualization portfolio together with Solaris Zones introduced already with Solaris 10 a few years ago. Let me explain how Oracle VM for X86 works: Oracle VM for x86 consists of two main parts: - The Oracle VM Server: Oracle VM Server is installed on bare metal and it is the hypervisor which is able to run virtual machines. It has a very small footprint. The ISO-Image of Oracle VM Server is only 200MB large. It is very small but efficient. You can install a OVM-Server in less than 5 mins by booting the Server with the ISO-Image assigned and providing the necessary configuration parameters (like installing an Linux distribution). After the installation, the OVM-Server is ready to use. That's all. - The Oracle VM-Manager: OVM-Manager is the central management tool where you can control your OVM-Servers. OVM-Manager provides the graphical user interface, which is an Application Development Framework (ADF) application, with a familiar web-browser based interface, to manage Oracle VM Servers, virtual machines, and resources. The Oracle VM Manager has the following capabilities: Create virtual machines Create server pools Power on and off virtual machines Manage networks and storage Import virtual machines, ISO files, and templates Manage high availability of Oracle VM Servers, server pools, and virtual machines Perform live migration of virtual machines I want to highlight one of the goodies which you can use if you are running Oracle VM for X86: Preconfigured, downloadable Virtual Machine Templates form edelivery With these templates, you can download completely preconfigured Virtual Machines in your environment, boot them up, configure them at first time boot and use it. There are templates for almost all Oracle SW and Applications (like Fusion Middleware, Database, Siebel, etc.) available. #3) Cloud Management The management of your cloud infrastructure is key. This is a day-to-day job. Acquiring HW, installing a virtualization layer on top of it is done just at the beginning and if you want to expand your infrastructure. But managing your cloud, keeping it up and running, deploying new services, changing your chargeback model, etc, these are the daily jobs. These jobs must be simple, secure and easy to manage. The Enterprise Manager 12c Cloud provides this functionality from one management cockpit. Enterprise Manager 12c uses Oracle VM Manager to control OVM Serverpools. Once you registered your OVM-Managers in Enterprise Manager, then you are able to setup your cloud infrastructure and manage everything from Enterprise Manager. What you need to do in EM12c is: ">Register your OVM Manager in Enterprise ManagerAfter Registering your OVM Manager, all the functionality of Oracle VM for X86 is also available in Enterprise Manager. Enterprise Manager works as a "Manger" of the Manager. You can register as many OVM-Managers you want and control your complete virtualization environment Create Roles and Users for your Self Service Portal in Enterprise ManagerWith this step you allow users to logon on the Enterprise Manager Self Service Portal. Users can request Virtual Machines in this portal. Setup the Cloud InfrastructureSetup the Quotas for your self service users. How many VMs can they request? How much of your resources ( cpu, memory, storage, network, etc. etc.)? Which SW components (templates, assemblys) can your self service users request? In this step, you basically set up the complete cloud infrastructure. Setup ChargebackOnce your cloud is set up, you need to configure your chargeback mechanism. The Enterprise Manager collects the resources metrics, which are used in a very deep level. Almost all collected Metrics could be used in the chargeback module. You can define chargeback plans based on configurations (charge for the amount of cpu, memory, storage is assigned to a machine, or for a specific OS which is installed) or chargeback on resource consumption (% of cpu used, storage used, etc). Or you can also define a combination of configuration and consumption chargeback plans. The chargeback module is very flexible. Here is a overview of the workflow how to handle infrastructure cloud in EM: Summary As you can see, setting up an Infrastructure Cloud Service with Oracle VM for X86 and Enterprise Manager 12c is really simple. I personally configured a complete cloud environment with three X86 servers and a small JBOD san box in less than 3 hours. There is no magic in it, it is all straightforward. Of course, you have to have some experience with Oracle VM and Enterprise Manager. Experience in setting up Linux environments helps as well. I plan to publish a technical cookbook in the next few weeks. I hope you found this post useful and will see you again here on our blog. Any hints, comments are welcome!

    Read the article

  • asus n550jv audio problem: no sound from notebook' speakers

    - by skywalker
    Ubuntu 13.10. The problem is: the internal speakers don't work. I have no problem when I'm using the headphones. There is no hardware issue since in windows 8 everything works perfectly(external subwoofer included). I'm trying to modify /etc/modprobe.d/alsa-base.conf but I can't find the correct model to put into: options snd-hda-intel model= The file HD-Audio-Models.txt doesn't contain the model for ALC668. Some info: :~sudo aplay -l **** List of PLAYBACK Hardware Devices **** card 0: MID [HDA Intel MID], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: MID [HDA Intel MID], device 7: HDMI 1 [HDMI 1] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: MID [HDA Intel MID], device 8: HDMI 2 [HDMI 2] Subdevices: 1/1 Subdevice #0: subdevice #0 card 1: PCH [HDA Intel PCH], device 0: ALC668 Analog [ALC668 Analog] Subdevices: 0/1 Subdevice #0: subdevice #0 :~$ sudo lspci -v | grep -A7 -i "audio" 00:03.0 Audio device: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller (rev 06) Subsystem: Intel Corporation Device 2010 Flags: bus master, fast devsel, latency 0, IRQ 52 Memory at f7a14000 (64-bit, non-prefetchable) [size=16K] Capabilities: [50] Power Management version 2 Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit- Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00 Kernel driver in use: snd_hda_intel -- 00:1b.0 Audio device: Intel Corporation 8 Series/C220 Series Chipset High Definition Audio Controller (rev 04) Subsystem: ASUSTeK Computer Inc. Device 11cd Flags: bus master, fast devsel, latency 0, IRQ 53 Memory at f7a10000 (64-bit, non-prefetchable) [size=16K] Capabilities: [50] Power Management version 2 Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+ Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00 Capabilities: [100] Virtual Channel PS info :~$ amixer -c 0 Simple mixer control 'IEC958',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'IEC958',1 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] Simple mixer control 'IEC958',2 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on] :~$ pacmd dump-volumes Welcome to PulseAudio! Use "help" for usage information. Sink 0: reference = 0: 76% 1: 76%, real = 0: 76% 1: 76%, soft = 0: 100% 1: 100%, current_hw = 0: 76% 1: 76%, save = yes Input 8: volume = 0: 100% 1: 100%, reference_ratio = 0: 100% 1: 100%, real_ratio = 0: 100% 1: 100%, soft = 0: 100% 1: 100%, volume_factor = 0: 100% 1: 100%, volume_factor_sink = 0: 100% 1: 100%, save = no Source 0: reference = 0: 100% 1: 100%, real = 0: 100% 1: 100%, soft = 0: 100% 1: 100%, current_hw = 0: 100% 1: 100%, save = no Source 1: reference = 0: 16% 1: 16%, real = 0: 16% 1: 16%, soft = 0: 100% 1: 100%, current_hw = 0: 16% 1: 16%, save = yes

    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

  • Is real estate boom again in India?

    - by skzameen
    The present real estate scenario in India is very good. The real estate boom in India is interlinked directly to the industrial, Commercial and economic growth with stability and strong presence of international companies throughout India have made the preferred destination for investment in real estate sector. India is a one of the fast growing economic stock markets For more information about residential and commercial projects or properties log on to www.zameen-zaidad.com, or email to [email protected] Contact Us Zameen-zaidad.com Ph: - +91-11-40024002 M: - +91-9810445860 Share your opinion for www.zameen-zaidad.com portal

    Read the article

  • *New Movie* featuring AutoVue value in Primavera Contract Management

    - by prasenjit.niyogi(at)oracle.com
    With the Oscar season approaching fast, one movie that you woudn't want to miss is the latest release from our post-production studios. Check out the new demo movie featuring the joint value of AutoVue's enterprise visualization within Primavera Contract Management. Please feel free share it with your partners, customers and prosepects. The video can be found on O.com (here), or on AutoVue's YouTube channel (here) or by simply clicking on the image below

    Read the article

< Previous Page | 47 48 49 50 51 52 53 54 55 56 57 58  | Next Page >