I’ve been working for quite some time now with Subversion but recently fell in love with Mercurial. Mercurial (like GIT or Bazaar) is a distributed version control system (DVCS). Coming from Subversion, it’s sometimes necessary to convert an existing Subversion repository to Mercurial. And that’s what this post is about.

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Friendship among Women:
A woman didn’t come home one night. The next morning
she told her husband that she had slept over at a
friend’s house. The man called his wife’s 10 best
friends. None of them knew anything about it.

Friendship among Men:
A man didn’t come home one night. The next morning he
told his wife that he had slept over at a friend’s
house. The woman called her husband’s 10 best friends.
Eight confirmed that he had slept over, and two said he was still there.

Heute, in unserem hochgradig modern ausgerüsteten Computer-Pool an der Uni:

iTunes unterstützt seit jeher das Ãœberblenden von Titel (engl. “cross-fade”). Während ein solches Feature bei einer zufälligen Wiedergabeliste sicherlich sinnvoll ist, gibt es bestimmte CDs (meistens Live-Aufnahmen), bei denen eine solche Ãœberblendung nicht so toll ist.

Heute bin ich nun über einen Tipp gestoßen, dass die Titelüberblendung in iTunes tatsächlich ziemlich “intelligent” ist. Denn sie beachtet die Option Unterbrechungsfreies Album, die für jeden Titel angegeben werden kann.

Ist Titel überblenden in den Optionen von iTunes aktiviert und wird nun ein Titel abgespielt, bei dem Unterbrechungsfreies Album auf Ja gesetzt ist, dann verzichtet iTunes bei diesem Titel auf die Titelüberblendung – es sei denn, die Option Zufällige Wiedergabe ist aktiviert. In diesem Fall werden auch Titel “übergeblendet”, die Teil eines unterbrechungsfreien Albums sind.

Zusammenfassung (bei aktivierter Titelüberblendung):

• Titel wird übergeblendet:

  • Bei Titeln mit Unterbrechungsfreies Album auf Nein gesetzt
  • Wenn Zufällige Wiedergabe aktiviert ist

• Titel wird nicht übergeblendet:

  • Bei Titeln mit Unterbrechungsfreies Album auf Ja gesetzt und wenn gleichzeitig Zufällige Wiedergabe nicht aktiv ist

(via Mac OS X Hints)

Today I did some testing on the performance of VMWare Fusion 3.1 regarding whether to use a 32-bit or a 64-bit guest system on a 64-bit host system. For the test I used:

• Machine: MacBook Pro 15” early 2010
• CPU: Intel Cor i5 2.4 GHz (Dual Core; 64-bit CPU)
• RAM: 4 GB 1067 MHz DDR3
• OS: Mac OS X 10.6.5 (with all updates)
• VMWare: VMWare Fusion 3.1.2 (332101)

For the testing I shut down all applications (that could be shut down) except for:

• VMWare Fusion (of course)
• Terminal
• TextWrangler

I also disabled Spotlight indexing for the duration of the test using (in Terminal):

$ mdutil -a -i off  # use "-i on" to reenable indexing

For testing I used an Ubuntu 10.04 Server Edition Linux either in the x86 (32-bit) and in the x64 (64-bit) version. Each version got one CPU and 512 MB RAM assigned (default values). I installed all updates (as of 2010-12-17) and also installed the packages “psmisc” and “bc”. The kernel version was 2.6.32-26. The VMWare Tools were not installed.

I then started VMWare Fusion (Virtual Machine Library only for now), and then called “purge” in the Terminal to free all inactive, unused memory for more correct information on how much memory is actually free. I then ran “vm_stat” (in Terminal), started the virtual machine, and ran “vm_stat” again to get the amount of memory actually used by the virtual machine.

Inside the virtual machine (i.e. in Ubuntu) I stopped cron and rsyslog to prevent them from interrupting the test, determined the free disk space (df -h) and the free memory (free -ok), and then calculated Pi with 3000 digits:

$ time echo "scale=3000; 4*a(1)" | (bc -l >/dev/null)

The results of the comparison can be found in the table below:

	32-bit	64-bit	Difference on 64-bit
Time to calculate Pi:	9.585s	8.823s	-7.9%
Memory consumption on the host system (MacOS):	482.3 MB	648.2 MB	+34.4%
Total/Used/Free memory in the guest system (Ubuntu):	496.96 MB / 35.22 MB / 461.74 MB	493.62 MB / 126.89 MB / 366.73 MB	+260.3% (used only)
Disk usage in the guest system (Ubuntu):	560 MB	581 MB	+3.8%

Observations:

• CPU speed: A 32-bit guest system on a 64-bit host system runs slower than a 64-bit guest system.
• Memory consumption: 64-bit guest systems require significantly more memory on the host system and on the guest system. In fact on the guest system the memory consumption seem to tripple (for some unknown reasons).
• Disk usage: As expected, disk usage is higher on a 64-bit system , but only slightly.

Conclusions: If memory consumption is an issue on your system (i.e. if you have not so much memory), then select a 32-bit guest system. It’ll be slightly slower but also consume less memory. If memory consumption is not an issue, select a 64-bit guest system.