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libimobiledevice: library to support iPhone, iPod Touch and iPad devices on Linux

libimobiledevice is a software library that talks the protocols to support iPhone®, iPod Touch® and iPad® devices on Linux. Unlike other projects, it does not depend on using any existing proprietary libraries and does not require jailbreaking. It allows other software to easily access the device's filesystem, retrieve information about the device and it's internals, backup/restore the device, manage SpringBoard® icons, manage installed applications, retrieve addressbook/calendars/notes and bookmarks and synchronize music and video to the device. The library is in development since August 2007 with the goal to bring support for these devices to the Linux Desktop.

http://www.libimobiledevice.org/

Filed under  //   ipad   iphone   ipod   library   linux  
Posted April 12, 2010 by email 
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Linux: Per-process namespaces

Linux has had this neat feature for quite some time now: since 2.4.19 according to the docs. Yet, it is neither very known nor very used. I couldn't even find a program that would create a new namespace for its subprocesses, similar to what chroot does with the root of the file hierarchy.

This neat feature allows each process to have a different set of mount points. While you most of the time want processes to share their mount points, there are some cases where you may want to have some processes have a different set of mount points. Combined with bind mounts, it can allow some useful setups.

http://glandium.org/blog/?p=217

Filed under  //   linux   mount   namespace   process  
Posted December 11, 2009 by email 
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Timechart: Finding out why your Linux computer performs the way it does has

  
Finding out why your Linux computer performs the way it does has been a hard task. Sure, there is Oprofile, and even 'perf' in recent kernels. There is LatencyTOP to find out where latencies happen.

 But all of these tools are rather limited when the software stack that has the performance issue is more complex than a single program. The tool that comes closest to being useful is `bootchart', but that has a rather limited resolution.

 http://blog.fenrus.org/?p=5

Filed under  //   charts   linux   performance   tools  
Posted September 21, 2009 by email 
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What is my NFS server doing?

From http://dev.eclipse.org/blogs/eclipsewebmaster/2009/09/02/what-is-my-nfs-server-doing/

If you're running an NFS daemon (nfsd), at some point in time you may have wondered what it was doing right now. If it's running in kernel space, tools like lsof and strace don't work, so you're left guessing.
 
After much Googleing and some inspecting of the Kernel source code, I discovered some debugging values that can be poked into /proc/sys/sunrpc/nfsd_debug. The most useful was 32, which I used like this:
 
echo 32 > /proc/sys/sunrpc/nfsd_debug; tail -f /var/log/messages | grep lookup
 
Essentially, this will give you an idea as to what files are being served up by nfsd. Be careful, though: on a busy NFS server, this will spew lots of output to /var/log/messages.
 
After stopping the above command with CTRL+C, don't forget to turn off nfsd_debug:
 
echo 0 > /proc/sys/sunrpc/nfsd_debug
 
With this trick I was able to find some nasties that were hurting our NFS performance.

Filed under  //   debug   linux   nfs  
Posted September 3, 2009 by email 
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