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Linux perf

Link to this post 25 Nov 10

Hello everyone,

I'm facing a performance issue on linux.

I have two system on the same hardware: one ubuntu and one slitaz. Slitaz is a small distro. I use it because I need a light system.

My problem is that slitaz is much slower than ubuntu.

I joined the results of a benchmark done using geekbench.

If you have any idea of where the problem might be please tell me.

Thank you very much.

[file name=geekbench.txt size=6073]http://www.linux.com/media/kunena/attachments/legacy/files/geekbench.txt[/file]

Link to this post 26 Nov 10

The difference could be caused by many potential differences such as your chosen filesystem, how the kernel is built, the running window manager, running services, etc... you will have to give us additional information for us to assist in diagnosing the performance issues.

Link to this post 26 Nov 10

I've done another bench with 0 load and it tells that the slitaz system has a memory problem.

Ubuntu :

Memory
Read Sequential
single-threaded scalar 1830 |||||||
Write Sequential
single-threaded scalar 1582 ||||||
Stdlib Allocate
single-threaded scalar 882 |||
Stdlib Write
single-threaded scalar 1267 |||||
Stdlib Copy
single-threaded scalar 2546 ||||||||||

Slitaz :
Memory
Read Sequential
single-threaded scalar 1770 |||||||
Write Sequential
single-threaded scalar 1525 ||||||
Stdlib Allocate
single-threaded scalar 809 |||
Stdlib Write
single-threaded scalar 505 ||
Stdlib Copy
single-threaded scalar 1011 ||||

As you can see, the Stdlib write and copy are more than twice better on ubuntu than on slitaz.
I guess this is because of my custom kernel on slitaz, but I don't know what options could improve memory management.


The whole slitaz bench (ubuntu one has not changed) : [file name=geekbench_slitaz.txt size=3035]http://www.linux.com/media/kunena/attachments/legacy/files/geekbench_slitaz.txt[/file]

Link to this post 27 Nov 10

It seems that it's a cache issue.

Someone knows which kernel option can custom the cache size (not the hardware one of course) and/or the number of slab objects avaibles ?

Link to this post 27 Nov 10

Could you explain how to used geekbench?

Link to this post 29 Nov 10

I just downloaded Geebench for linux and runned ./geekbench_x86_32.

It outputed the results I posted.

I'm not a bench expert but in my case theses benchmarks highlighted a memory problem on slitaz. And further investigation (using slabtop) revealed that it's a cache problem.

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