From 6cbe0cb6f6a08ef0114132a12bf2d6b15354f46c Mon Sep 17 00:00:00 2001 From: FOWEPJF255 Date: Thu, 15 Oct 2026 20:53:01 +0800 Subject: [PATCH] docs: clarify --fast level bounds and selection --- programs/zstd.1.md | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/programs/zstd.1.md b/programs/zstd.1.md index 1721441dfbb..08d1642c5b1 100644 --- a/programs/zstd.1.md +++ b/programs/zstd.1.md @@ -121,8 +121,13 @@ the last one takes effect. * `--fast[=#]`: switch to ultra-fast compression levels. If `=#` is not present, it defaults to `1`. + `#` must be a positive integer. Values above the maximum supported by the + linked library (`-ZSTD_minCLevel()`, currently 131072) are clamped to that + maximum. The higher the value, the faster the compression speed, at the cost of some compression ratio. + Start with `--fast=1` or `--fast=4` and benchmark on your own data before + choosing a higher value; the speed and ratio trade-off depends on the input. This setting overwrites compression level if one was set previously. Similarly, if a compression level is set after `--fast`, it overrides it. * `-T#`, `--threads=#`: