Richard Purdie 663c259ffa bitbake: data: Add support for new BB_HASH_CODEPARSER_VALS for cache optimisation
Currently the codeparser cache ends up being extended for every parse run
since there are values in the functions such as the result of os.getpid()
from LOGFIFO in OE-Core.

Digging into that issue, there are also lots of similar but different
functions being parsed where the change might just be a path to WORKDIR,
a change in PN or PV or something like DATE/TIME.

There is no reason we have to use these changing values when computing the
dependenies of the functions. Even with a small tweak like:

BB_HASH_CODEPARSER_VALS = "LOGFIFO=/ T=/ WORKDIR=/ DATE=1234 TIME=1234 PV=0.0-1 PN=nopn"

the cache is reduced from ~4.6MB, increasing by ~300kb for every parse run
to around 1.3MB and remaining static for oe-core and meta-oe. In my local
build, admittedly heavily experimented with, the cache had grown to 120MB.

The benefits of doing this are:

 * faster load time for bitbake since the cache is smaller to read from disk
   and load into memory
 * being able to skip saving the cache upon shutdown
 * lower memory footprint for bitbake
 * faster codeparser data lookups (since there is less data to search)

We only use these special values when passing code fragments to the codeparser
to parse so the real variable values should otherwise be used in the hash data.

The overall effect of this change, combined with others to avoid saving unchanged
cache files can be ~2s on a ~16s parse on my local system and results in a more
responsive feeling bitbake. It also allows parsing performance to be investigated
more consistently.

(Bitbake rev: f24bbaaddb36f479a59a958e7fc90ef454c19473)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
2023-01-24 21:59:44 +00:00
2021-07-19 18:07:21 +01:00

Poky

Poky is an integration of various components to form a pre-packaged build system and development environment which is used as a development and validation tool by the Yocto Project. It features support for building customised embedded style device images and custom containers. There are reference demo images ranging from X11/GTK+ to Weston, commandline and more. The system supports cross-architecture application development using QEMU emulation and a standalone toolchain and SDK suitable for IDE integration.

Additional information on the specifics of hardware that Poky supports is available in README.hardware. Further hardware support can easily be added in the form of BSP layers which extend the systems capabilities in a modular way. Many layers are available and can be found through the layer index.

As an integration layer Poky consists of several upstream projects such as BitBake, OpenEmbedded-Core, Yocto documentation, the 'meta-yocto' layer which has configuration and hardware support components. These components are all part of the Yocto Project and OpenEmbedded ecosystems.

The Yocto Project has extensive documentation about the system including a reference manual which can be found at https://docs.yoctoproject.org/

OpenEmbedded is the build architecture used by Poky and the Yocto project. For information about OpenEmbedded, see the OpenEmbedded website.

Contribution Guidelines

The project works using a mailing list patch submission process. Patches should be sent to the mailing list for the repository the components originate from (see below). Throughout the Yocto Project, the README files in the component in question should detail where to send patches, who the maintainers are and where bugs should be reported.

A guide to submitting patches to OpenEmbedded is available at:

https://www.openembedded.org/wiki/How_to_submit_a_patch_to_OpenEmbedded

There is good documentation on how to write/format patches at:

https://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines

Where to Send Patches

As Poky is an integration repository (built using a tool called combo-layer), patches against the various components should be sent to their respective upstreams:

OpenEmbedded-Core (files in meta/, meta-selftest/, meta-skeleton/, scripts/):

BitBake (files in bitbake/):

Documentation (files in documentation/):

meta-yocto (files in meta-poky/, meta-yocto-bsp/):

If in doubt, check the openembedded-core git repository for the content you intend to modify as most files are from there unless clearly one of the above categories. Before sending, be sure the patches apply cleanly to the current git repository branch in question.

CII Best Practices

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