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Posted to commits@mahout.apache.org by "aloha1357 (via GitHub)" <gi...@apache.org> on 2026/06/07 19:20:51 UTC
[PR] [QDP] Pr3 shared memory fwt [mahout]
aloha1357 opened a new pull request, #1388:
URL: https://github.com/apache/mahout/pull/1388
### Related Issues
<!-- Closes #123 -->
related #1385
### Changes
- [ ] Bug fix
- [x] New feature
- [x] Refactoring
- [ ] Documentation
- [ ] Test
- [ ] CI/CD pipeline
- [ ] Other
### Why
For smaller qubit counts ($N \le 12$), calculating the Fast Walsh-Hadamard Transform (FWT) using multiple global memory kernel launches becomes heavily DRAM bandwidth-bound (launch overhead and global memory roundtrips dominate the execution time). By keeping the entire state vector within the GPU's Shared Memory (which is much faster and has lower latency than DRAM), we can fuse the operations into a single kernel launch.
### How
- **Operator Fusion Kernel (`iqp_phase_fwt_normalize_tc_kernel`):** Created a new fused kernel that handles three steps entirely within Shared Memory:
1. Computes the IQP phase and writes it directly to `extern __shared__ cuDoubleComplex shared_state[]`.
2. Performs the in-place Hadamard FWT over the shared memory buffer.
3. Normalizes the final amplitudes and writes them out to Global Memory.
- **Dynamic Dispatch:** Updated `launch_iqp_encode_tc` to dynamically allocate Shared Memory and dispatch to this fused kernel when `num_qubits <= FWT_SHARED_MEM_THRESHOLD`.
## 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] Pr3 shared memory fwt [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] closed pull request #1388: [QDP] Pr3 shared memory fwt
URL: https://github.com/apache/mahout/pull/1388
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Re: [PR] [QDP] Pr3 shared memory fwt [mahout]
Posted by "rich7420 (via GitHub)" <gi...@apache.org>.
rich7420 commented on PR #1388:
URL: https://github.com/apache/mahout/pull/1388#issuecomment-5030953796
plz resolve the conflict
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Re: [PR] [QDP] Pr3 shared memory fwt [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1388:
URL: https://github.com/apache/mahout/pull/1388#issuecomment-4941530655
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] Pr3 shared memory fwt [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1388:
URL: https://github.com/apache/mahout/pull/1388#issuecomment-5419564538
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] Pr3 shared memory fwt [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1388:
URL: https://github.com/apache/mahout/pull/1388#issuecomment-5519044549
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] Pr3 shared memory fwt [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] closed pull request #1388: [QDP] Pr3 shared memory fwt
URL: https://github.com/apache/mahout/pull/1388
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Re: [PR] [QDP] Pr3 shared memory fwt [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1388:
URL: https://github.com/apache/mahout/pull/1388#issuecomment-6116411207
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] Pr3 shared memory fwt [mahout]
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #1388:
URL: https://github.com/apache/mahout/pull/1388#issuecomment-5986775742
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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