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What’s virtual address limit of 32bit/64bit Linux kernel?
RHEL 5 code 32bit: include/asm-i386/processor.h /* * User space process size: 3GB (default). */ #define TASK_SIZE (PAGE_OFFSET) 64bit: include/asm-x86_64/processor.h /* * User space process size. 47bits minus one guard page. */ #define TASK_SIZE64 (0x800000000000UL – 4096) /* This decides where the kernel will search for a free chunk of vm * space during mmap’s. */ […]
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Quotes from “The Secret Life Of Walter Mitty”
To see the world, things dangerous to come to, to see behind walls, draw closer, to find each other, and to feel. That is the purpose of life. Sometimes I don’t. If I like a moment, for me, personally, I don’t like to have the distraction of the camera. I just want to stay in […]
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Personal memo for ‘Automatic NUMA Balancing’
Automatic NUMA Balancing It is described in Documentation/sysctl/kernel.txt numa_balancing Enables/disables automatic page fault based NUMA memory balancing. Memory is moved automatically to nodes that access it often. Enables/disables automatic NUMA memory balancing. On NUMA machines, there is a performance penalty if remote memory is accessed by a CPU. When this feature is enabled the kernel […]
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crash extension ‘pstree’
‘crash’ is useful tool to analyse system crashes or debugging in Linux system. It has many useful commands, but sometimes I wanted to get full picture of process list that was running at the time of crash. You can get process list with ‘ps’, but if you want to get hierarchical view, only ‘ps -p’ […]
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A small tool to manage my projects
If you are working with only on language, it would be quite easy to manage your source code. But, as there are many different requirements and circumstances, we are facing to work with several different languages which come with different tool set. I’ve tried to keep my project under one directory, but still it’s quite […]
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External network doesn’t work in OpenStack running on VMWare fusion?
I’ve been hard time to figure out why my openstack doesn’t communicate with outside and it’s always saying ‘Down’ when I checked external network in router. It turned out that is the issue with ‘promiscuous mode’. In default, it’s requires to have authentication for entering promiscuous mode. By turning it off, the network works fine […]
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What’s cloud computing
Some summary from http://en.wikipedia.org/wiki/Cloud_computing Abstract In computer networking, cloud computing is a phrase used to describe a variety of computing concepts that involve a large number of computers connected through a communication network such as the Internet. It is very similar to the concept of utility computing. In science, cloud computing is a synonym for […]
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How to convert Flac to MP3 on Mac
To convert FLAG files into MP3, you can find many good commercial software. But, if you don’t have many files and just need a quick and cheap way, you can try the below instead. It requires to have MacPorts installed, but it’s just for installing ffmpeg. $ sudo port install ffmpeg Now, you just need […]
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How to improve the nova storage performance
If you are using KVM for virtualisation in OpenStack, you might notice some big slowness with the virtual storage. You can improve the performance by using the hypervisor’s volume group directly. You just need to create a volume group and specify that in /etc/nova/nova.conf. libvirt_images_type=lvm libvirt_images_volume_group=
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Some basic swift commands
I’m not using Swift much, but there’s a time that I had to deal with this to troubleshoot a problem. Here’s the some commands to check Swift status. $ swift stat $ swift stat $ swift stat $ swift list $ swift list –prefix= $ swift –all download $ swift download $ swift download $ […]
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Popular slogans in Facebook’s culture
Done is better than perfect Move fast and break things Stay focused and keep shipping This journey is 1 percent finished
Sungju's Slow Life
Personal journal
Sungju's Slow Life 