Summary

Significant research has been done on the performance of SD cards. The results indicate that cards perform better with certain classes of filesystem configuration (e.g. alignment matching eraseblocks). The image construction scripts should apply as many of these optimisations as possible when creating preinstalled images to be written to SD. Further, when preinstall images are first expanded, jasper should attempt to optimise the expanded filesystem for the specific media into which it is expanding.

Release Note

With Ubuntu 11.10 or later, images targeting SD cards are optimised to SD flash geometry, significantly improving performance, reducing application startup time, and booting more quickly.

Rationale

MMC controllers provide fairly limited bandwidth. Using unoptimised storage configuration can reduce performance by 90% from these already low numbers. These apparently simple fixes will provide a very significant improvement to many common operations.

User stories

Assumptions

Design

You can have subsections that better describe specific parts of the issue.

Implementation

This section should describe a plan of action (the "how") to implement the changes discussed. Could include subsections like:

UI Changes

Should cover changes required to the UI, or specific UI that is required to implement this

Code Changes

Code changes should include an overview of what needs to change, and in some cases even the specific details.

Migration

Include:

Test/Demo Plan

It's important that we are able to test new features, and demonstrate them to users. Use this section to describe a short plan that anybody can follow that demonstrates the feature is working. This can then be used during testing, and to show off after release. Please add an entry to http://testcases.qa.ubuntu.com/Coverage/NewFeatures for tracking test coverage.

This need not be added or completed until the specification is nearing beta.

Unresolved issues

This should highlight any issues that should be addressed in further specifications, and not problems with the specification itself; since any specification with problems cannot be approved.

BoF agenda and discussion

Use this section to take notes during the BoF; if you keep it in the approved spec, use it for summarising what was discussed and note any options that were rejected.


CategorySpec

ARM/Specs/PreinstallSDOptimisation (last edited 2011-04-28 17:59:33 by persia)