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Posted to commits@mahout.apache.org by "aloha1357 (via GitHub)" <gi...@apache.org> on 2026/06/07 19:34:06 UTC
[PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
aloha1357 opened a new pull request, #1390:
URL: https://github.com/apache/mahout/pull/1390
### Related Issues
<!-- Closes #123 -->
related #1385
### Changes
- [ ] Bug fix
- [x] New feature
- [ ] Refactoring
- [ ] Documentation
- [ ] Test
- [ ] CI/CD pipeline
- [ ] Other
### Why
As established in the previous Kronecker Decomposition PR, a significant bottleneck in processing high-qubit circuits ($N \ge 14$) is memory. A traditional $O(4^N)$ matrix representation for the full Dense Hadamard transform completely exhausts modern GPU VRAM limits (causing Out-Of-Memory errors).
Even with the Kronecker Decomposition splitting the matrix into smaller blocks, generating and storing the explicit dense $H$ matrices in memory before applying Tensor Core operations is highly inefficient.
We need a way to perform Dense Matrix Multiplications (GEMM) on the Tensor Cores *without ever storing the Hadamard Matrix in Global Memory*.
### How
This PR introduces the **Matrix-Free Implicit Hadamard Ozaki Engine**.
- **Implicit Matrix Generation:** The `ImplicitHadamardOzakiEngine` leverages the structural properties of the Hadamard matrix ($h_{i,j} = (-1)^{\text{popc}(i \& j)}$) to calculate the matrix elements *on-the-fly* directly inside Shared Memory.
- **Ozaki Multi-pass Tensor Core Execution:** Using the Ozaki INT8 scheme, we utilize the `.m16n8k32.s8` Tensor Core instructions to perform the GEMM natively in hardware. Because the Hadamard values are always $\pm 1$, we experience absolutely zero quantization error despite using the INT8 pipeline.
- **Removed Fallback:** Replaced the `naive_implicit_hadamard_gemm_kernel` placeholder from PR 4 with the actual calls to `engine.execute_implicit_hadamard`.
- **Build System Fix:** Updated `build.rs` to drop the unsupported `sm_75` (Turing) target fallback, as this specific Tensor Core instruction explicitly requires `sm_80` (Ampere) or higher.
## Checklist
- [x] Added or updated unit tests for all changes (Verified passing against existing CI test suite)
- [x] Added or updated documentation for all changes (Added explanatory inline comments for PR)
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] closed pull request #1390: [QDP] [feature] Pr5 implicit hadamard engine
URL: https://github.com/apache/mahout/pull/1390
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1390:
URL: https://github.com/apache/mahout/pull/1390#issuecomment-6332343103
This pull request has been automatically marked as stale because it has not had any activity for 30 days.
It will be closed in another 7 days if no further activity occurs. Thank you for your contribution. If you'd like to keep this open, leave any comment and the stale label will be removed.
You can always ask for help on the [Mahout dev mailing list](https://lists.apache.org/list.html?dev@mahout.apache.org) or in [GitHub Discussions](https://github.com/apache/mahout/discussions).
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1390:
URL: https://github.com/apache/mahout/pull/1390#issuecomment-4949586221
This pull request has been automatically marked as stale because it has not had any activity for 30 days.
It will be closed in another 7 days if no further activity occurs. Thank you for your contribution. If you'd like to keep this open, leave any comment and the stale label will be removed.
You can always ask for help on the [Mahout dev mailing list](https://lists.apache.org/list.html?dev@mahout.apache.org) or in [GitHub Discussions](https://github.com/apache/mahout/discussions).
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1390:
URL: https://github.com/apache/mahout/pull/1390#issuecomment-5275128225
This pull request has been automatically marked as stale because it has not had any activity for 30 days.
It will be closed in another 7 days if no further activity occurs. Thank you for your contribution. If you'd like to keep this open, leave any comment and the stale label will be removed.
You can always ask for help on the [Mahout dev mailing list](https://lists.apache.org/list.html?dev@mahout.apache.org) or in [GitHub Discussions](https://github.com/apache/mahout/discussions).
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] closed pull request #1390: [QDP] [feature] Pr5 implicit hadamard engine
URL: https://github.com/apache/mahout/pull/1390
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1390:
URL: https://github.com/apache/mahout/pull/1390#issuecomment-5754350139
This pull request has been automatically marked as stale because it has not had any activity for 30 days.
It will be closed in another 7 days if no further activity occurs. Thank you for your contribution. If you'd like to keep this open, leave any comment and the stale label will be removed.
You can always ask for help on the [Mahout dev mailing list](https://lists.apache.org/list.html?dev@mahout.apache.org) or in [GitHub Discussions](https://github.com/apache/mahout/discussions).
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1390:
URL: https://github.com/apache/mahout/pull/1390#issuecomment-5364282809
This pull request has been automatically closed because there has been no more activity in the 7 days since being marked stale.
Please feel free to reopen or open a new pull request if you'd still like this to be addressed. You can always ask for help on the [Mahout dev mailing list](https://lists.apache.org/list.html?dev@mahout.apache.org) or in [GitHub Discussions](https://github.com/apache/mahout/discussions).
Thanks again for your contribution!
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Re: [PR] [QDP] [feature] Pr5 implicit hadamard engine [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1390:
URL: https://github.com/apache/mahout/pull/1390#issuecomment-6512828488
This pull request has been automatically closed because there has been no more activity in the 7 days since being marked stale.
Please feel free to reopen or open a new pull request if you'd still like this to be addressed. You can always ask for help on the [Mahout dev mailing list](https://lists.apache.org/list.html?dev@mahout.apache.org) or in [GitHub Discussions](https://github.com/apache/mahout/discussions).
Thanks again for your contribution!
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