David Luhman's blog

Improving performance with multi-threading on a multi-core CPU

The other day I was downloading several podcasts from the net, while doing an expensive rsync across my slow home network. My dual core CPU was showing 50% on one CPU, about 0% on the other, and my network was shown at about 1%.

My iTunes had a "download multiple streams" checkbox that was unchecked. I thought running multiple streams might actually slow things down due to thrashing/context switching, but I checked it to give me multiple streams.

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Diversification with long-term bonds and commodities

Lately, I've been looking to increase the diversification in my retirement portfolio by investing in both commodities AND long-term bonds.

Crazy? Aren't these diametrically opposed views? Commodities love inflation, just like long-term bonds hate inflation.

It's hard to say where inflation is headed, although at least relative to now it seems likely to go up. But how much more inflation can we expect, and more importantly, now much of that is already priced in long-term bond prices.

Building Git on Red Hat-based systems

I had a case where I had to build Git on an older Red Hat based system. Unfortunately, the system was so old that yum wasn't really supported. So I had to install the needed libraries (RPMs) "by hand" via rpm -i. There was one package that I had to update via rpm -U.

On my rather bare system, I found I had to install the following RPMs to get Git to compile :

cpp
curl
curl-devel
e2fsprogs-devel
gcc
glibc-devel
glibc-headers
glibc-kernheaders
krb5-devel
krb5-libs
make
openssl
openssl-devel
wget
zlib-devel
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Migrating to a 64-bit operating system (OS)

When upgrading servers, you may encounter this question : Should we stay at at 32-bit OS, or 'upgrade' to a 64-bit OS?

To me, the big advantage of a 64-bit OS is the ability to address (use) more than 4 gigabytes of RAM. I sometimes bump into that limit on my desktop,
so I think it's best to have a 64 bit OS for servers.

Larger memory space isn't the only advantage, however. From Wikipedia :

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Spell checking source code

I'm not sure of the cost/benefit of spell checking of source code, but there seem to be a couple cheap/free utilities that can help with this.

Free Python package :
http://pypi.python.org/pypi/scspell/0.1.0

Commercial shareware - $59.99 (Windows)
http://www.brothersoft.com/source-code-spell-checker-48748.html

Another commercial shareware version - $39.99 (Windows)
http://download.cnet.com/Source-Code-Spell-Checker/3000-2352_4-10341753....

Here's one man's experience checking Java source code with a "generic plain English" spell checker :

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Git patch tutorial

I had some patches in one Git repository that I wanted to apply to a different repository. Here's a useful link I found on this :

http://stackoverflow.com/questions/327249/seeking-examples-of-workflow-u...

Here's what I did.

First, copy the original repository you want to get patch from. This may not be necessary in all cases, but in my case the original repository was on another machine, so this just puts everything on the same machine.

  
    $ git clone ssh://me@example.com/repos/origRepo
    $ cd origRepo
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OVF - Open Virtualization Format

If you're into computer virtualization, you should probably be familiar with OVF.

The "Open Virtualization Format" is a supposed standard for interchanging VMs between vendors (VMware, Microsoft, VirtualBox etc.) Here's a good overview of the format :

http://www.dmtf.org/about/cloud-incubator/OVF_-_Building_Block_for_Cloud...

Most of my experience with virtualization has been with VMware, Xen, Virtual PC and recently with VirtualBox on the desktop.

I wanted to see how OVF might work, so I found this minimal OVF version of Solaris :

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Git difftool and vimdiff

For the most part, I use TkDiff as the Git difftool when working under X Windows. TortoiseGit also has a nice GUI diff tool for when I do occassional work on Windows.

However, when working in a Linux "terminal" environment, your Git difftool choices seem to be limited to vimdiff. This is OK, but most of the color schemes under vimdiff are terrible.

I recommend using a vimdiff friendly color scheme like "greens" which is described here :
http://www.vim.org/scripts/script.php?script_id=1253

Here's how to set yourself up to use vimdiff as Git's difftool.


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Phase 4 of D-Link DNS-323 hacking - Running Optware

I'm using the DNS-323 primarily for automated backups, and making Git backups is part of this. The fonz fun plug (ffp) has a lot of stuff on it (rsync, lighttpd), but I didn't see Git. So I was looking to add Git via Optware.

I was able to add Optware, but the Git version couldn't clone across ssh nor rsync. Cloning across the git protocol did, however work. But I'll likely just use the rsync client to get my Git repositories. Git seems to work fine if the repo came via a plain rsync client.

root:/mnt/HD_a2/tmp# git clone ssh://root@192.168.1.108/tmp/gitTest

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