docs(server): clarify that --ctx-size is total context divided among parallel slots

When using `--parallel N`, the `--ctx-size` value is the total context
divided among all slots, not the per-slot context. This is a common source
of confusion.

For example:
- `--ctx-size 4096 --parallel 4` → each slot gets 1024 tokens
- To get 4096 tokens per slot with 4 parallel slots, use `--ctx-size 16384`

Fixes #11681

Author: kitaekatt

tools/server/README.md

@@ -46,7 +46,7 @@ The project is under active development, and we are [looking for feedback and co
 | `--cpu-strict-batch <0\|1>` | use strict CPU placement (default: same as --cpu-strict) |
 | `--prio-batch N` | set process/thread priority : 0-normal, 1-medium, 2-high, 3-realtime (default: 0)<br/> |
 | `--poll-batch <0\|1>` | use polling to wait for work (default: same as --poll) |
-| `-c, --ctx-size N` | size of the prompt context (default: 4096, 0 = loaded from model)<br/>(env: LLAMA_ARG_CTX_SIZE) |
+| `-c, --ctx-size N` | size of the prompt context (default: 4096, 0 = loaded from model). When using `--parallel N`, this is the **total** context divided among all slots (each slot gets `ctx-size / parallel` tokens). To allocate X tokens per slot with N parallel slots, set `--ctx-size` to `X * N`.<br/>(env: LLAMA_ARG_CTX_SIZE) |
 | `-n, --predict, --n-predict N` | number of tokens to predict (default: -1, -1 = infinity)<br/>(env: LLAMA_ARG_N_PREDICT) |
 | `-b, --batch-size N` | logical maximum batch size (default: 2048)<br/>(env: LLAMA_ARG_BATCH) |
 | `-ub, --ubatch-size N` | physical maximum batch size (default: 512)<br/>(env: LLAMA_ARG_UBATCH) |
@@ -72,7 +72,7 @@ The project is under active development, and we are [looking for feedback and co
 | `-ctk, --cache-type-k TYPE` | KV cache data type for K<br/>allowed values: f32, f16, bf16, q8_0, q4_0, q4_1, iq4_nl, q5_0, q5_1<br/>(default: f16)<br/>(env: LLAMA_ARG_CACHE_TYPE_K) |
 | `-ctv, --cache-type-v TYPE` | KV cache data type for V<br/>allowed values: f32, f16, bf16, q8_0, q4_0, q4_1, iq4_nl, q5_0, q5_1<br/>(default: f16)<br/>(env: LLAMA_ARG_CACHE_TYPE_V) |
 | `-dt, --defrag-thold N` | KV cache defragmentation threshold (DEPRECATED)<br/>(env: LLAMA_ARG_DEFRAG_THOLD) |
-| `-np, --parallel N` | number of parallel sequences to decode (default: 1)<br/>(env: LLAMA_ARG_N_PARALLEL) |
+| `-np, --parallel N` | number of parallel sequences to decode (default: 1). The total context (`--ctx-size`) is divided equally among these slots.<br/>(env: LLAMA_ARG_N_PARALLEL) |
 | `--mlock` | force system to keep model in RAM rather than swapping or compressing<br/>(env: LLAMA_ARG_MLOCK) |
 | `--no-mmap` | do not memory-map model (slower load but may reduce pageouts if not using mlock)<br/>(env: LLAMA_ARG_NO_MMAP) |
 | `--numa TYPE` | attempt optimizations that help on some NUMA systems<br/>- distribute: spread execution evenly over all nodes<br/>- isolate: only spawn threads on CPUs on the node that execution started on<br/>- numactl: use the CPU map provided by numactl<br/>if run without this previously, it is recommended to drop the system page cache before using this<br/>see https://github.com/ggml-org/llama.cpp/issues/1437<br/>(env: LLAMA_ARG_NUMA) |