[ExecuTorch][WebGPU] Optimize reduction-family kernels to cooperative shared-memory#21225
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🔗 Helpful Links🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/21225
Note: Links to docs will display an error until the docs builds have been completed. ⏳ No Failures, 30 PendingAs of commit b70ddf2 with merge base 4a26c64 ( This comment was automatically generated by Dr. CI and updates every 15 minutes. |
This was referenced Jul 22, 2026
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… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
added a commit
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
added a commit
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
JCNTH
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Jul 24, 2026
… shared-memory Pull Request resolved: #21225 Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction. Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant. ghstack-source-id: 406388754 @exported-using-ghexport Differential Revision: [D112257649](https://our.internmc.facebook.com/intern/diff/D112257649/)
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Stack from ghstack (oldest at bottom):
Problem: The reduction ops (amax/amin/argmax/sum/mean), softmax/log_softmax, and native_group_norm's reduce pass used naive one-thread-per-row serial loops — far below Vulkan's optimization level, where backends/vulkan/runtime/graph/ops/glsl/reduce.glsl uses a cooperative shared-memory reduction.
Solution: Rewrite each to Vulkan's cooperative design — one workgroup per reduction row/group, each thread reduces a strided slice into a workgroup shared array, thread 0 aggregates the partials. Dispatch changed to one workgroup per row. argmax preserves torch's first-index tie-break; softmax keeps numerical stability + the log variant.
@exported-using-ghexport
Differential Revision: D112257649
Differential Revision: D112257649