Entries from 2015-01-01 to 1 year

Play with Boost::Any

Linux ABI

Motivation: When I read: ./linux/types.h , there is comment saying that: aligned u64 should be used in defining kernel<->userspace ABIs to avoid common 332/64-bit comapt problems. What is ABI: It stands for Application Binary Interface. AB…

C++ 14 std::experimental::pmr::memory_resource

memory_resource

Dynamic Memory Allocation - Jemalloc

What I want to know is not how to install, use or whatever. I just want to know how it works. Understanding jemallo

Deep Dive into Neutron

Neutron ML2 The Modular Layer2 (ml2) plugin is a framework allowing OpenStack Networking to simultaneusly utilze the variety of layer2 networking technology found in complex real-world data centres. It currently works with the existing ope…

How does Ceph OSD Handle the Request from Client

It's good starting point where you completely and perfectly understand how Ceph works. This page will be update soon to put more perfect explanation coming from more analisys. /* * Operation started. */#./src/osd/OSD.cc5676 bool OSD::dispa…

OpenStack Manual Installation - 4th Topic: To Build Cinder Component

Notice: This series is to expect to use kernel 3.10.0-229. 1.What Cinder provides. It provides block storage which allows block devices to be exposed and connected to compute instances for expanded storage, better performance and integrati…

Bootstrap of Systemd

Everything is defined in: /usr/lib/systemd/system/ and in: Bootstrap of systemd at the boot timedocs.google.com

Capturing network traffic with pcap

In the field of computer network administration, pcap (packet capture) consists of an application programming interface (API) for capturing network traffic. Unix-like systems implement pcap in the libpcap library; Windows uses a port of li…

OpenStack Manual Installation - 4th Topic: To Build Glance Component

Notice: This series is to expect to use kernel 3.10.0-229. 1. What Glance provides. It provides a catalog service for storing and querying virtual disk images. Glance also provides an end-to-end solution for cloud disk image management wit…

Aside Reversibility - Ruby

This was quite interesting to me. irb(main):001:0> me1 = "puts 'Life with Linux'"=> "Life with Linux" irb(main):002:0> puts me1puts 'Life with Linux'=> nil irb(main):003:0> eval me1Life with Linux=> nil irb(main):004:0> bytes_in_binary1 = …

OpenStack Manual Installation - 3rd Topic: To Build Swift Component

Notice: This series is to expect to use kernel 3.10.0-229. 1. What Swift provides is A massively scalable and redundant object store conceptually similar to Amazon S3. S3: Simple Storage Service To provide this scalability and redundancy, …

Receiving Flow of Packets in The Linux Kernel

Notice: Descriptions of LAYER in this document are based on the OSI model. Layer5 Three system calls: write sendto sendmsg end up in: __sock_sendmsg() which does: security_sock_sendmsg() to check prmissions, then forwards the message to th…

OpenStack Manual Installation - 2nd Topic: To Build Keystone Component

Notice: This series is to expect to use kernel 3.10.0-229. Keystone, what does it do , and how it works. 1. Introduction Keystone provides identity and access policy services for all components in the OpenStack family. It implements it's o…

OpenStack Manual Installation - 1st Topic: To Build Message Broker System

Notice: This series is to expect to use kernel 3.10.0-229. These days, It's getting easier to build OpenStack infrastructure because so many contributors have been struggling with, working for OpenStack. In this series, I will write not on…

How git works - Part 1

■ Working with Git To start working with Git, you just need to run ""git init" command. It turns the current directory into the Git working directory and creates the repository in the .git (hidden) directory created there. * git init: To i…

REALLOC - Part1

The realloc() function changes the size of the memory block pointed to by ptr to size bytes. void* realloc(void* oldmem, size_t bytes) The contents will be unchanged in the range from the start of the region up to the minimum of the old an…

Error: autofs stop working - part1

Suddenly autofs stop working from time time. Here is an error message in syslog on ldap client. Feb 3 11:14:58 <hostname> automount[2462]: __init_ldap_connection: lookup(ldap): TLS required but START_TLS failed: Can't contact LDAP server __init_ldap</hostname>…

dmidecod

demidecode --type: 0: BIOS 1: System 2: Base Board 3: Chassis 4: Processor 5: Memory Controller 6: Memory Module 7: Cache 8: Port Connector 9: System Slots 10: On Board Devices 11: OEM Strings 12: System Configuration Options 13: BIOS Lang…

Systemtap

RHEL6.5では、カーネルと同じリビジョンの kernel-debuginfo と kernel-debuginfo-common を、debuginfo-install でインストールするだけで、stap が機能したけど、RHEL7 では、上手くいかない。 RHEL6.5 [root@x201s ~]# rpm -qa | grep debugkernel-debugi…