CELF Project proposal: UBIFS mount-time speedups

CELF Project proposal: UBIFS mount-time speedups

[Tim Bird]

Summary: Improve UBIFS mounting time

Proposer: Tim Bird

Description:
UBIFS is a next-generation flash-based file system for Linux.
It is a read/write file system, which supports compression
and has good performance.  However, it's mount times are not
very good.  This affects overall Linux boot time, for a UBIFS-based
embedded system.

The purpose of this project would be to investigate mount performance
issues, and try to resolve them.  One suggestion is to keep the
bad block table on flash, instead of re-scanning it on every boot.
It is not known if algorithms to do this are covered by existing
flash management patents.

Related work:
* UBIFS
** http://en.wikipedia.org/wiki/UBIFS
** http://lwn.net/Articles/276025/
* UBI2
** see portions of http://www.mjmwired.net/kernel/Documentation/filesystems/ubifs.txt
* Mount times
** http://osl.sed.hu/wiki/ubifs/index.php/Mount_results
** http://elinux.org/images/f/f8/CELFJamboree30-UBIFS_update.pdf

Scope: This project might take about 4 months

Notes:
Toshiba may already be working on this project.

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Corporation of America
=============================

Re: CELF Project proposal: UBIFS mount-time speedups

[Kyungmin Park]

Summary: UBI block mapping on flash (UBI2 requirement)

Proposer: Kyungmin Park

Description: UBI scans all physical block at boot time. and maintain it at RAM.
Usually this scan time takes almost 2 or more seconds. To reduce the this time
UBI maintain block mapping information on flash and use it at next boot time.

Also it have to support or provide rescan mechanism at runtime to use
single image into another flash

* UBI2
** see portions of
http://www.mjmwired.net/kernel/Documentation/filesystems/ubifs.txt

Scope: This project might take about 2 months.

Re: CELF Project proposal: UBIFS mount-time speedups

[Tim Bird]

Kyungmin Park wrote:
> Summary: UBI block mapping on flash (UBI2 requirement)

This looks like a subset of the project described at:
http://elinux.org/CELF_Project_Proposal/UBIFS_mount_time_speedups

I've added your description as a comment in that proposal.

Thanks!
 -- Tim

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Corporation of America
=============================