# Ruby performance degraded on custom kernel

**URL:** <https://www.ruby-forum.com/t/ruby-performance-degraded-on-custom-kernel/112512>\
**Category:** Ruby\
**Created:** [August 20, 2007, 2:45pm UTC](https://www.ruby-forum.com/t/ruby-performance-degraded-on-custom-kernel/112512 "2007-08-20T14:45:10Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![cubiq](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/b19c9b/32.png) [@cubiq](https://www.ruby-forum.com/u/cubiq)\
**Post date:** [August 20, 2007, 2:45pm UTC](https://www.ruby-forum.com/t/ruby-performance-degraded-on-custom-kernel/112512/1 "2007-08-20T14:45:10Z")

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Hello list,

I have a rather odd question regarding ruby’s performance on a system  
with a vanilla kernel from [kernel.org](http://kernel.org) version 2.6.18.1.

I have two identical systems.  
One system has a minimal debian etch system installed which I use as a  
host.  
The other system is using a vanilla kernel from [kernel.org](http://kernel.org).

The ruby installed is 1.8.5 patchlevel 2.

The ruby interpreter is 50% slower on the vanilla kernel system. Is also  
uses a lot more CPU.

So I wonder if there are any kernel parameters that you know about that  
could affect the performance of the ruby interpreter?

Any other ideas would be greatly appreciated.

Cheers,  
Henrik

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<div class="post-metadata">

**Author:** ![cubiq](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/b19c9b/32.png) [@cubiq](https://www.ruby-forum.com/u/cubiq)\
**Post date:** [August 20, 2007, 4:13pm UTC](https://www.ruby-forum.com/t/ruby-performance-degraded-on-custom-kernel/112512/2 "2007-08-20T16:13:16Z")

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Henrik Z. wrote:

> The ruby installed is 1.8.5 patchlevel 2.  
> Henrik  
> Well … I’m not sure off the top of my head what it could be, but if  
> one system is _pure_ Etch and the other is _pure_ Etch with identical  
> hardware, but you’ve _only_ substituted the kernel from [kernel.org](http://kernel.org), I’d  
> say it’s something that Debian has patched in the kernel that’s  
> preventing a problem. 🙂

What’s the goal here? Is there something in the [kernel.org](http://kernel.org) kernel you  
_can’t_ do with Etch? What sort of script is the Ruby interpreter  
running? It seems unlikely unless you’re doing something strange that  
the Ruby interpreter would spend a lot of time dealing with the kernel.  
If you have “top” running, is the overall CPU time “user”, “system” or  
“nice”? Something else, like “irq” or “softirq”?

I’d put this one in the class of, “Doctor, it hurts when I do this.”

“OK, then don’t do that.”

😉

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<div class="post-metadata">

**Author:** ![cubiq](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/b19c9b/32.png) [@cubiq](https://www.ruby-forum.com/u/cubiq)\
**Post date:** [August 20, 2007, 4:49pm UTC](https://www.ruby-forum.com/t/ruby-performance-degraded-on-custom-kernel/112512/3 "2007-08-20T16:49:01Z")

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Thanks for your response.

Sorry, I wasn’t that clear with the environment. I’m building an  
embedded system so I cannot use the debian install on the other system.

Either way, its no problem anymore. I solved it and it’s kinda  
embarrassing. When I did a stress test with C code only I noticed the  
same slowdown. I then noticed that the CPU somehow had degraded itself  
to 1/3 of its speed…

Weee