[Docs] Add docs for `SGLANG_` and `SGL_` environment variables (#6206)

docs/references/environment_variables.md

+# Environment Variables
+
+SGLang supports various environment variables that can be used to configure its runtime behavior. This document provides a comprehensive list and aims to stay updated over time.
+
+*Note: SGLang uses two prefixes for environment variables: `SGL_` and `SGLANG_`. This is likely due to historical reasons. While both are currently supported for different settings, future versions might consolidate them.*
+
+## General Configuration
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_USE_MODELSCOPE` | Enable using models from ModelScope | `false` |
+| `SGLANG_HOST_IP` | Host IP address for the server | `0.0.0.0` |
+| `SGLANG_PORT` | Port for the server | auto-detected |
+| `SGLANG_LOGGING_CONFIG_PATH` | Custom logging configuration path | Not set |
+| `SGLANG_DISABLE_REQUEST_LOGGING` | Disable request logging | `false` |
+| `SGLANG_HEALTH_CHECK_TIMEOUT` | Timeout for health check in seconds | `20` |
+
+## Performance Tuning
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_ENABLE_TORCH_INFERENCE_MODE` | Control whether to use torch.inference_mode | `false` |
+| `SGLANG_ENABLE_TORCH_COMPILE` | Enable torch.compile | `true` |
+| `SGLANG_SET_CPU_AFFINITY` | Enable CPU affinity setting (often set to `1` in Docker builds) | `0` |
+| `SGLANG_ALLOW_OVERWRITE_LONGER_CONTEXT_LEN` | Allows the scheduler to overwrite longer context length requests (often set to `1` in Docker builds) | `0` |
+| `SGLANG_IS_FLASHINFER_AVAILABLE` | Control FlashInfer availability check | `true` |
+| `SGLANG_SKIP_P2P_CHECK` | Skip P2P (peer-to-peer) access check | `false` |
+| `SGL_CHUNKED_PREFIX_CACHE_THRESHOLD` | Sets the threshold for enabling chunked prefix caching | `8192` |
+| `SGLANG_FUSED_MLA_ENABLE_ROPE_FUSION` | Enable RoPE fusion in Fused Multi-Layer Attention | `1` |
+
+## DeepGEMM Configuration (Advanced Optimization)
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGL_ENABLE_JIT_DEEPGEMM` | Enable Just-In-Time compilation of DeepGEMM kernels | `"true"` |
+| `SGL_JIT_DEEPGEMM_PRECOMPILE` | Enable precompilation of DeepGEMM kernels | `"true"` |
+| `SGL_JIT_DEEPGEMM_COMPILE_WORKERS` | Number of workers for parallel DeepGEMM kernel compilation | `4` |
+| `SGL_IN_DEEPGEMM_PRECOMPILE_STAGE` | Indicator flag used during the DeepGEMM precompile script | `"false"` |
+| `SGL_DG_CACHE_DIR` | Directory for caching compiled DeepGEMM kernels | `~/.cache/deep_gemm` |
+| `SGL_DG_USE_NVRTC` | Use NVRTC (instead of Triton) for JIT compilation (Experimental) | `"0"` |
+| `SGL_USE_DEEPGEMM_BMM` | Use DeepGEMM for Batched Matrix Multiplication (BMM) operations | `"false"` |
+
+## Memory Management
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_DEBUG_MEMORY_POOL` | Enable memory pool debugging | `false` |
+| `SGLANG_CLIP_MAX_NEW_TOKENS_ESTIMATION` | Clip max new tokens estimation for memory planning | Not set |
+| `SGLANG_DETOKENIZER_MAX_STATES` | Maximum states for detokenizer | Default value based on system |
+| `SGL_DISABLE_TP_MEMORY_INBALANCE_CHECK` | Disable checks for memory imbalance across Tensor Parallel ranks | Not set (defaults to enabled check) |
+
+## Model-Specific Options
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_AITER_MOE` | Use AITER MOE implementation | `false` |
+| `SGLANG_INT4_WEIGHT` | Enable INT4 weight quantization | `false` |
+| `SGLANG_MOE_PADDING` | Enable MoE padding (sets padding size to 128 if value is `1`, often set to `1` in Docker builds) | `0` |
+| `SGLANG_FORCE_FP8_MARLIN` | Force using FP8 MARLIN kernels even if other FP8 kernels are available | `false` |
+
+## Distributed Computing
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_BLOCK_NONZERO_RANK_CHILDREN` | Control blocking of non-zero rank children processes | `1` |
+| `SGL_IS_FIRST_RANK_ON_NODE` | Indicates if the current process is the first rank on its node | `"true"` |
+| `SGLANG_PP_LAYER_PARTITION` | Pipeline parallel layer partition specification | Not set |
+
+## Testing & Debugging (Internal/CI)
+
+*These variables are primarily used for internal testing, continuous integration, or debugging.*
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_IS_IN_CI` | Indicates if running in CI environment | `false` |
+| `SGLANG_AMD_CI` | Indicates running in AMD CI environment | `0` |
+| `SGLANG_TEST_RETRACT` | Enable retract decode testing | `false` |
+| `SGLANG_RECORD_STEP_TIME` | Record step time for profiling | `false` |
+| `SGLANG_TEST_REQUEST_TIME_STATS` | Test request time statistics | `false` |
+| `SGLANG_CI_SMALL_KV_SIZE` | Use small KV cache size in CI | Not set |
+
+## Profiling & Benchmarking
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_TORCH_PROFILER_DIR` | Directory for PyTorch profiler output | `/tmp` |
+
+## Storage & Caching
+
+| Environment Variable | Description | Default Value |
+| --- | --- | --- |
+| `SGLANG_DISABLE_OUTLINES_DISK_CACHE` | Disable Outlines disk cache | `true` |

docs/references/general.rst

@@ -10,4 +10,5 @@ General Guidance
    faq.md
    learn_more.md
    modelscope.md
+   environment_variables.md
    production_metrics.md