Skip to content

Remove legacy size classes. - #995

Draft
copybara-service[bot] wants to merge 1 commit into
masterfrom
test_983774672
Draft

copybara-service[bot] wants to merge 1 commit into
masterfrom
test_983774672

Conversation

@copybara-service

Copy link
Copy Markdown

Remove legacy size classes.

want_legacy_size_classes has been a no-op for a while without any
complaints, so now remove the underlying code. We still keep
the target, but will clean it up in a future step.

Note that this is not a no-op for generated code; the maximum number
of size classes drops, which means several structures (e.g.,
the per-CPU metadata slabs) become smaller, and that we can fit
CompactSizeClass (used in the page map) into one byte instead of two.
This means PageMap3::Leaf shrinks from 10kLeafLength bytes to
9
kLeafLength, a 10% decrease.

want_legacy_size_classes has been a no-op for a while without any
complaints, so now remove the underlying code. We still keep
the target, but will clean it up in a future step.

Note that this is not a no-op for generated code; the maximum number
of size classes drops, which means several structures (e.g.,
the per-CPU metadata slabs) become smaller, _and_ that we can fit
CompactSizeClass (used in the page map) into one byte instead of two.
This means PageMap3::Leaf shrinks from 10*kLeafLength bytes to
9*kLeafLength, a 10% decrease.

PiperOrigin-RevId: 983774672
@google-cla

google-cla Bot commented Sep 18, 2026

Copy link
Copy Markdown

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

0 participants