---
license: mit
pretty_name: BoLT Parallelism Configuration (64 GPUs)
task_categories:
- other
tags:
- bayesian-optimization
- benchmark
- parallelism-configuration
- tabular
size_categories:
- n<1K
---

# pco64

Throughput of distributed LLM training as a function of the parallelism
configuration, on 64 GPUs across 16 hosts.
Tabular benchmark for the `bolt` problem `pco64`: the 780
rows are the full candidate set.

- **Objective** `throughput_mean`, to maximise. `NaN` where the run OOMed, since
  no throughput is observed at all -- a hidden (crash) constraint, not a bad value.
- **Constraint** `ran_successfully`. 560 of 780
  configurations run; the rest exhaust GPU memory. Feasibility is only learnable
  by attempting the run, so it cannot be decoupled from the objective.
- **Auxiliary** `peak_mem` (GB, `inf` when infeasible), `peak_mem_normalised`
  (the run's own feasibility margin, `< 0` iff feasible, a fixed pad value when
  infeasible) and `overall_time` (wall clock in seconds, `NaN` when infeasible).

`peak_mem` does **not** define the constraint: feasible runs here reach
79.3 GB, so no memory threshold separates the
classes. `peak_mem_normalised` does, by construction.

## Instance context

Constant for every row; these describe the instance, not the search space.

| field | value |
|---|---|
| `num_layers` | 64 |
| `num_attention_heads` | 64 |
| `hidden_size` | 5120 |
| `ffn_hidden_size` | 25600 |
| `batch_size` | 512 |
| `seq_length` | 8192 |
| `log2_num_gpus` | 6 |
| `log2_num_hosts` | 4 |
| `log2_grad_accum_steps` | 0 |

## Columns

The table is the raw sweep export, unchanged. Every knob halves or doubles, so
the sizes arrive as `log2_*` and their levels are evenly spaced. `zero_stage` is
the raw stage (0/2/3); `bolt` searches it as an ordinal 0/1/2.

| column | role | meaning |
|---|---|---|
| `log2_dp_size` | input | log2 of data-parallel size |
| `log2_tp_size` | input | log2 of tensor-parallel size |
| `log2_pp_size` | input | log2 of pipeline-parallel size |
| `log2_cp_size` | input | log2 of context-parallel size |
| `log2_sp_size` | input | log2 of sequence-parallel size |
| `log2_dp_bucket_size_mb` | input | log2 of DDP gradient bucket size in MB |
| `zero_stage` | input | ZeRO stage, one of [0, 2, 3] |
| `log2_num_model_chunks` | input | log2 of number of model chunks |
| `log2_grad_accum_steps` | context | log2 of gradient accumulation steps |
| `ran_successfully` | output | ground-truth constraint label |
| `throughput_mean` | output | objective, `NaN` when infeasible |
| `throughput_std` | output | spread over the timed steps, `NaN` when infeasible |
| `peak_mem_normalised` | output | feasibility margin, `< 0` iff feasible |
| `overall_time` | output | wall clock in seconds, `NaN` when infeasible |
| `all_time_steps` | output | per-step times, as a string list |
| `peak_mem` | output | peak GPU memory in GB, `inf` when infeasible |
| `peak_mem_per_gpu` | output | per-GPU peak memory, as a string list |

## Best observed

`throughput_mean` = 0.27068 at `log2_dp_size`=4, `log2_tp_size`=2, `log2_pp_size`=0, `log2_cp_size`=0, `log2_sp_size`=2, `log2_dp_bucket_size_mb`=6, `zero_stage`=2, `log2_num_model_chunks`=0
(peak memory 74.2 GB).

## Provenance

`data_64depth-64gpus.csv`, converted to parquet unchanged.