From d1801babad495be2a3eb1d974e1daf9714c5b0fd Mon Sep 17 00:00:00 2001 From: Mark Johnston Date: Thu, 4 Apr 2024 10:54:25 -0400 Subject: [PATCH] tarfs.5: Document the importance of zstd framing Reviewed by: des, kib MFC after: 1 week Sponsored by: Klara, Inc. Differential Revision: https://reviews.freebsd.org/D44628 --- share/man/man5/tarfs.5 | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/share/man/man5/tarfs.5 b/share/man/man5/tarfs.5 index 29999b8066f..5378491b9c9 100644 --- a/share/man/man5/tarfs.5 +++ b/share/man/man5/tarfs.5 @@ -61,6 +61,19 @@ sysctl setting and tunable. Setting it to 0 will reset it to its default value. Note that changes to this setting only apply to filesystems mounted after the change. +.Pp +When the backing tar file is compressed with +.Xr zstd 1 , +I/O performance can be improved by ensuring that compressed data is +broken up into multiple frames. +This helps minimize unnecessary decompression work. +When using +.Xr bsdtar 1 +to create the tar file, this can be achieved using the +.Cm zstd:max-frame-size +and +.Cm ztsd:frame-per-file +options. .Sh DIAGNOSTICS If enabled by the .Dv TARFS_DEBUG -- 2.45.0