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Fix fp16 overflow #1084

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Fix fp16 overflow #1084

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2 changes: 1 addition & 1 deletion cpp/src/neighbors/detail/ann_utils.cuh
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Original file line number Diff line number Diff line change
Expand Up @@ -148,7 +148,7 @@ struct config<float> {
};
template <>
struct config<half> {
using value_t = half;
using value_t = float;
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@achirkin achirkin Jul 4, 2025

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Please check whether this is used outside the IVF-Flat. Changing the accumulation type like this can have a drastic impact on performance.

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@hhy3 hhy3 Jul 4, 2025

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I did simple benchmark and it showed no significant differences. I'll use cuvs ann-bench to get a more detailed benchmark results later

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@cjnolet cjnolet Jul 22, 2025

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@hhy3 any updates here? We're about to begin burndown for 25.08 release. Should we consider this for 25.08 or push to 25.10 (October)?

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@hhy3 hhy3 Jul 23, 2025

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@cjnolet hi, push it to 25.10, thx

static constexpr double kDivisor = 1.0;
};
template <>
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12 changes: 6 additions & 6 deletions cpp/src/neighbors/ivf_flat/ivf_flat_interleaved_scan.cuh
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Expand Up @@ -138,8 +138,8 @@ struct loadAndComputeDist {
for (int k = 0; k < Veclen; ++k) {
compute_dist(dist, queryRegs[k], encV[k]);
if constexpr (ComputeNorm) {
norm_query += queryRegs[k] * queryRegs[k];
norm_data += encV[k] * encV[k];
norm_query += (AccT)(queryRegs[k] * queryRegs[k]);
norm_data += (AccT)(encV[k] * encV[k]);
}
}
}
Expand Down Expand Up @@ -173,8 +173,8 @@ struct loadAndComputeDist {
T q = raft::shfl(queryReg, d + k, raft::WarpSize);
compute_dist(dist, q, encV[k]);
if constexpr (ComputeNorm) {
norm_query += q * q;
norm_data += encV[k] * encV[k];
norm_query += (AccT)(q * q);
norm_data += (AccT)(encV[k] * encV[k]);
}
}
}
Expand All @@ -199,8 +199,8 @@ struct loadAndComputeDist {
T q = raft::shfl(queryReg, d + k, raft::WarpSize);
compute_dist(dist, q, enc[k]);
if constexpr (ComputeNorm) {
norm_query += q * q;
norm_data += enc[k] * enc[k];
norm_query += (AccT)(q * q);
norm_data += (AccT)(enc[k] * enc[k]);
}
}
}
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