Introduction As we know, network subsystems are important in computer systems since they are I/O systems and need to be optimized with many algorithms and skills. This article will introduce how QEMU/KVM [2] network part works. In order to put everything simple and easy to understand, we will begin with several examples and then understand
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Tag: OS
How to Install Paravirtualized CentOS 7 DomU on Xen
Posted onThis post introduces how to install a paravirtualized CentOS 7 DomU on Xen. The very common way of installing DomU does not work for CentOS 7. A little trick to set the repository and the network used by the VM should be used by adding a setting strings to the “extra=” field for this VM.
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Building and Installing Linux Kernel from the Source Code in an Existing Linux OS
Posted onBuilding Linux kernel may sound a complex and geek-only thing. However, as Linux kernel itself has much less depended tools/packages compared to other software packages, it is quite easy to compile, build and install a Linux kernel from the source code in an existing Linux OS. Building Linux kernel is needed if you need to
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Spring Shell Technology For Java development
Posted onThis post is about the Spring Shell technology and its use in java. Experts of java development India have shared their best knowledge in this post for Spring Shell with the community people. If you have anything to ask, do it at the end. Technology: It is command line tool for Java applications to interact
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x-data-plane feature in QEMU/KVM
Posted onAbstract In systems, sometimes, we use one global lock to keep synchronization among different threads. This principle also happens in QEMU/KVM (http://wiki.qemu.org/Main_Page) system. However, this may cause lock contention problem. The performance/scalability of whole system will be decreased. In order to solve this problem in QEMU/KVM, x-data-plane feature is designed/implemented, which the high-level idea is
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How to Change Linux Account Password Through SSH: A Beginners’ Tutorial
Posted onPeople are sometimes given access to Linux/Unix and asked to change their initial passwords. But for beginners, changing a Linux/Unix password is not an easy task, especially when there is only SSH log on allowed to the Linux/Unix server. This post introduces how to change password of user USER on host HOST remotely using SSH.
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How to Clean RAID Signatures on Linux
Posted onRAID systems such as MegaRAID add signatures to disks to maintain the infomration on these didks. When we simply remove these disks and install them to another server, Linux on the new server may detect these RAID signature infomration and refuses to continue write to the disk. Here is one example that mkfs reports “apparently
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What Is the Name of the Linux-based OS: A Survey
Posted onYou may already well know “Linux” and may also use the “operating system based on the Linux kernel” directly or indirectly (you are indirectly using it now as this site is hosted on Linux). But how should we name the OS based on Linux? You may know there is GNU/Linux naming controversy. Different people have
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iPhone Connecting to Internet Using Windows PC’s Network through USB Cable
Posted onNote that this was only tested on certain combinations like this (Windows 7 with iOS 8), this (Windows 7 with iOS 7), this and this (Windows 7 with iOS 9.3.2 (iphone 6s)). Windows 7 seems a possible Windows OS that can work. Recently, I tested it on Windows 8 and iOS 9. Unfortunately, it did
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How to Turn GNOME terminal to a Pop-up Terminal
Posted onA pop-up terminal is great and handy on Linux and similar OS. On KDE, Yakuake is great. On Gnome or GTK, I ever tried Guake. It is quite good. However, it has not been as mature, stable and figure-rich as gnome-terminal. One day, I got this idea: why not using a script/program to manage the
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Keyboard Key Mapping for Emacs: Evil Mode and Rearranging Alt, Ctrl and Win Keys
Posted onCtrl keys are important and possibly most frequently used in Emacs. However, it is painful on today’s common PC keyboards since Ctrl keys are usually in the corner of the keyboard main area. Why the key mappings in Emacs are designed like this? After it was designed, Emacs was commonly on the Lisp Machine keyboards
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How to Create Fedora 20 Domain-U on Fedora 20 Domain-0
Posted onIn this post, creating a file-backed virtual block device (VBD) and installing Fedora 20 in the Xen DomU via internet will be introduced. This domain is created on a Fedora 20 Dom0 as introduced in https://www.systutorials.com/installing-xen-on-fedora-20-as-domain-0/. For better performance, you may consider using LVM backed VM. Create file-backed VBD The actual space of VBD will
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How to Set Up RAID0 in MegaRAID BIOS with New Disks
Posted onThe LSI MegaRAID is widely used like in IBM x3620M3 servers. This post introduces the process with screenshots of how to configure the new disks and set up RAID0 in the MegaRAID BIOS for reference by other and myself. It is illustrated with one example by adding a new 2TB hard disk and creating a
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Unified Linux Login and Home Using OpenLDAP and NFS
Posted onIn this post, how to unified Linux login and home directory using OpenLDAP and NFS/automount will be introduced. 0. System environment This solution is tested on Fedora 12 systems and CentOS 5. LDAP and NFS server: IP: 10.0.0.2 OS: Fedora 12 x86_64 ldap base dn: “dc=lgcpu1″ Clients: IP: 10.0.0.1/24 OS: Fedora 12 x86_64 1. LDAP
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How to Measure Time Accurately in Programs
Posted onIt is quite common to measure the time in programs using APIs like clock() and gettimeofday(). We may also want to measure the time “accurately” for certain purposes, such as measuring a small piece of code’s execution time for performance analysis, or measuring the time in time-sensitive game software. It is hard to measure the
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Java Calling Native Functions in .DLL on Windows
Posted onHow to call a function in .dll from Java on Windows is introduced in this post with an example. Platforms used: OS: Microsoft Windows XP [5.1.2600] C to .dll compiler: MS Visual Studio 2008 JDK: java -version java version “1.6.0_05” Java(TM) SE Runtime Environment (build 1.6.0_05-b13) Java HotSpot(TM) Client VM (build 10.0-b19, mixed mode, sharing)
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Installing Fedora 17 PV Domain-U on Xen with PXE Booting
Posted onAn introduction to the general method of installing Domain-U on Xen is introduced here: Setting Up Stable Xen DomU with Fedora: Unmodified Fedora 12 on top of Xenified Fedora 12 Dom0 with Xen (this is a general introduction, some details are changed, such as ‘xl’ replacing ‘xm’, LVM backing the disk for higher performance. But
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Setting Up Xen DomU on Fedora Linux (Fedora 12)
Posted onCreating file-backed virtual block device (VBD) for Xen virtual machines and installing Fedora 12 in Xen DomU via internet will be introduced. Note that this tutorial is based on a pretty old OS (Fedora 12). But the method here is still valid while some minor details may need to be changed for latest Xen and
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How to Set Date, Time and Timezone in Linux
Posted onHow to set date, time and timezone on Linux/Unix box will be introduced in this post. Unix time, or POSIX time which is a system for describing points in time is the number of seconds elapsed since midnight UTC on the morning of January 1, 1970, not counting leap seconds. The number of seconds elapsed
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Create and Manage Virtual Machines on Xen
Posted onIn this post, these content are introduced: Create and manage file-backed virtual block device (VBD) for virtual machines on xen. Install Fedora 11 via internet as DomU on top of xen. Manage virtual machines using xm. Create file-backed VBD: The actual space of VBD will be the amount of disk the virtual machine used. And
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