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Re: [Xen-devel] xend leaks/bugs/etc

To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] xend leaks/bugs/etc
From: Jacob Gorm Hansen <jacobg@xxxxxxx>
Date: Wed, 20 Apr 2005 00:54:36 -0700
Cc: ncmike@xxxxxxxxxx, Harry Butterworth <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Allen Short <washort@xxxxxxxxxx>
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Ian Pratt wrote:

I think the goal should be to have the least amount of code (regardless of language) in whatever is running as a daemon.

Exactly - the least amount of code that meets functional requirements.


It's hard to beat python for this sort of thing...

Not if you factor in the footprint of the python compiler and runtime and its large set of standard modules, and its unpredictable runtime performance (memory leaks and lack of static checking). It seems to me the 'python for xend' experiment has failed, and that this is further evidenced by that fact that a) Anthony/IBM has decided to write a competing implementation from scratch b) Xend developers blame Twisted, and now c) Twisted developers blame Xend. Short of name-calling, I do not see how we can proceed from here.

No other serious OS has vital components written in interpreted dynamically typed languages, I do not see why Xen needs to be the only one. Perhaps it is true that development is a little faster in Python (I have extensive Python experience, yet I have felt much more comfortable reading and modifying code in the C-implemented parts of the system than in Xend which remains a complete blackbox to me), but still we are making users pay for our (perceived) increased productivity with their memory, their system stability, and their runtime performance. I am not an engineer, but to me this seems like poor engineering.

The Intermezzo project tried something similar some years back, having a kernel component in C and a user-level file server in Perl. While there was great progress in the beginning, the project more or less died when the limitations of Perl were reached. A rewrite in C was attempted, but at that point the project had run out of steam.

Jacob

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