Better estimate entropy costs (#680)#680
Open
terrelln wants to merge 9 commits into
Open
Conversation
|
@terrelln has exported this pull request. If you are a Meta employee, you can view the originating Diff in D102352000. |
meta-codesync
Bot
changed the title
terrelln
added a commit
to terrelln/openzl
that referenced
this pull request
Apr 27, 2026
Summary: ## Huffman Changes * Add parameters `ZL_ENTROPY_MIN_GAIN_BYTES_PID` (default 32) and `ZL_ENTROPY_MIN_GAIN_PCT_PID` (default 1) to the entropy graph that control the minimum gain in bytes or percent to allow entropy compression. * Improve Huffman estimation by building the Huffman CTable in the entropy graph to estimate the compressed size exactly, and if Huffman is selected passing the CTable down to the Huffman node. * Improve estimation of Huffman and FSE header sizes based on empirical evidence. ## LZ Changes * Use `ZL_ENTROPY_MIN_GAIN_BYTES_PID` to set a more conservative bound on when to use Huffman based on the input size, rather than the size of the Huffman compressed stream. * Have `ZL_GRAPH_COMPRESS_SMALL_LENGTHS` (which is private) forward its parameters to `ZL_GRAPH_HUFFMAN` so we can control `ZL_ENTROPY_MIN_GAIN_BYTES_PID`. Differential Revision: D102352000
terrelln
force-pushed
the
export-D102352000
branch
2 times, most recently
from
ab5b6a9 to
55453d2
Compare
terrelln
added a commit
to terrelln/openzl
that referenced
this pull request
Apr 27, 2026
Summary: ## Huffman Changes * Add parameters `ZL_ENTROPY_MIN_GAIN_BYTES_PID` (default 32) and `ZL_ENTROPY_MIN_GAIN_PCT_PID` (default 1) to the entropy graph that control the minimum gain in bytes or percent to allow entropy compression. * Improve Huffman estimation by building the Huffman CTable in the entropy graph to estimate the compressed size exactly, and if Huffman is selected passing the CTable down to the Huffman node. * Improve estimation of Huffman and FSE header sizes based on empirical evidence. ## LZ Changes * Use `ZL_ENTROPY_MIN_GAIN_BYTES_PID` to set a more conservative bound on when to use Huffman based on the input size, rather than the size of the Huffman compressed stream. * Have `ZL_GRAPH_COMPRESS_SMALL_LENGTHS` (which is private) forward its parameters to `ZL_GRAPH_HUFFMAN` so we can control `ZL_ENTROPY_MIN_GAIN_BYTES_PID`. Differential Revision: D102352000
terrelln
added a commit
to terrelln/openzl
that referenced
this pull request
Apr 27, 2026
Summary: Pull Request resolved: facebook#680 ## Huffman Changes * Add parameters `ZL_ENTROPY_MIN_GAIN_BYTES_PID` (default 32) and `ZL_ENTROPY_MIN_GAIN_PCT_PID` (default 1) to the entropy graph that control the minimum gain in bytes or percent to allow entropy compression. * Improve Huffman estimation by building the Huffman CTable in the entropy graph to estimate the compressed size exactly, and if Huffman is selected passing the CTable down to the Huffman node. * Improve estimation of Huffman and FSE header sizes based on empirical evidence. ## LZ Changes * Use `ZL_ENTROPY_MIN_GAIN_BYTES_PID` to set a more conservative bound on when to use Huffman based on the input size, rather than the size of the Huffman compressed stream. * Have `ZL_GRAPH_COMPRESS_SMALL_LENGTHS` (which is private) forward its parameters to `ZL_GRAPH_HUFFMAN` so we can control `ZL_ENTROPY_MIN_GAIN_BYTES_PID`. Differential Revision: D102352000
terrelln
force-pushed
the
export-D102352000
branch
from
55453d2 to
fa0fbbc
Compare
Differential Revision: D104843371
Summary: The LZ encoder capped `matchLength()` at `UINT16_MAX` because sequence match lengths are stored as `uint16_t`. If the match had been walked backward at least `UINT16_MAX` bytes, then the match finding process would resume at a position which had already been inserted into the hash table. This would result in match with `distance <= 0` and corruption would ensue. Differential Revision: D104838040
Differential Revision: D105332025
Summary: LZ must be a dynamic graph because it invokes a multi-input node (ZL_NODE_MUX_LENGTHS). But we need to allow overriding the successors in a serialized graph for training and configurability. So do the same thing that FieldLZ does, which sets the index of the `customGraph` as a local int param. When the local int param is set, set the corresponding successor to that graph. Differential Revision: D105367885
Summary: As title Differential Revision: D105368972
Differential Revision: D102620101
Differential Revision: D102351635
Summary: Pull Request resolved: facebook#680 ## Huffman Changes * Add parameters `ZL_ENTROPY_MIN_GAIN_BYTES_PID` (default 32) and `ZL_ENTROPY_MIN_GAIN_PCT_PID` (default 1) to the entropy graph that control the minimum gain in bytes or percent to allow entropy compression. * Improve Huffman estimation by building the Huffman CTable in the entropy graph to estimate the compressed size exactly, and if Huffman is selected passing the CTable down to the Huffman node. * Improve estimation of Huffman and FSE header sizes based on empirical evidence. ## LZ Changes * Use `ZL_ENTROPY_MIN_GAIN_BYTES_PID` to set a more conservative bound on when to use Huffman based on the input size, rather than the size of the Huffman compressed stream. * Have `ZL_GRAPH_COMPRESS_SMALL_LENGTHS` (which is private) forward its parameters to `ZL_GRAPH_HUFFMAN` so we can control `ZL_ENTROPY_MIN_GAIN_BYTES_PID`. Differential Revision: D102352000
terrelln
force-pushed
the
export-D102352000
branch
from
fa0fbbc to
5191aca
Compare
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary:
Huffman Changes
ZL_ENTROPY_MIN_GAIN_BYTES_PID(default 32) andZL_ENTROPY_MIN_GAIN_PCT_PID(default 1) to the entropy graph that control the minimum gain in bytes or percent to allow entropy compression.LZ Changes
ZL_ENTROPY_MIN_GAIN_BYTES_PIDto set a more conservative bound on when to use Huffman based on the input size, rather than the size of the Huffman compressed stream.ZL_GRAPH_COMPRESS_SMALL_LENGTHS(which is private) forward its parameters toZL_GRAPH_HUFFMANso we can controlZL_ENTROPY_MIN_GAIN_BYTES_PID.Differential Revision: D102352000