Linuxtiny update

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Linux-tiny update
Tim Bird Chair, CELF Architecture Group Senior
Software Engineer, Sony
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Linux-tiny Project Update

• Introduction to Linux-tiny project
• History
• Status
• Results

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Introduction to Linux-tiny

• What is Linux-tiny?
• A collection of patches to reduce the memory size
  of the Linux kernel
• Currently, a collection of about 40 patches
• Had as many as 110 patches at one time
• Some patches mainlined, some are out-of-date

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Linux-tiny Patch Areas

• Configurable static data structure size
• Configurable code elimination
• Eliminate a subsystem or feature, depending on
  kernel configuration
• Moving inlines into stand-alone functions
• Kernel instrumentation and analysis tools for
  memory usage reporting

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Linux-tiny History

• Started in 2003 by Matt Mackall
• CELF sponsored Matt in 2005/2006
• Mainlined the top 17 patches from Linux-tiny in
  Linux kernel version 2.6.10-14
• New maintainer Michael Opdenacker
• Volunteered at OLS, 2007 (June)
• Michael is an experienced embedded Linux trainer
• See http//free-electrons.com/

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Current status

• Revival announced!
• Code status
• Results

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Revival Announced!

• Project revival was announced on LKML
• See http//lkml.org/lkml/2007/9/19/295
• Very positive response, including from Andrew
  Morton
• He wants to put patches in his tree soon
• Good article on project at
• http//lwn.net/Articles/251573

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Code Status

• Project is active
• Latest release is available for 2.6.23 kernel
• Project wiki page is http//elinux.org/Linux_Tiny
  
• Patch status is maintained at
• http//elinux.org/Linux_Tiny_Patch_Details
• Patches are maintained as quilt archives
• Tarball of patches directory, with a series file
• Can apply with 'patch', but easier with 'quilt'

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Sub-patch Count Summary
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Testing Results

• Automated test was written
• Some results written to CELF test lab wiki
• http//testlab.celinuxforum.org/otlwiki/ConfigSize
  TestResults
• Test needs a bit more refinement
• Runtime memory measurement is inaccurate

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Results
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What's next?

• Send some patches to mainline!!!!
• Update documentation
• Linux kernel size tuning guide
• Better runtime memory measurement
• Need to measure runtime memory earlier in boot
  sequence
• Want to get cache_accounting working on slob
  allocator
• Please download and test the code
• Every bug report is important

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Resources

• Web site
• http//elinux.org/Linux_Tiny
• Mailing List
• linux-tiny_at_selenic.com