The branch stable/14 has been updated by markj:
URL:
https://cgit.FreeBSD.org/src/commit/?id=753de7251761e9ce7dfe7a6196b6d2ef7806d996
commit 753de7251761e9ce7dfe7a6196b6d2ef7806d996
Author: Mark Johnston <ma...@freebsd.org>
AuthorDate: 2024-04-05 15:28:55 +0000
Commit: Mark Johnston <ma...@freebsd.org>
CommitDate: 2024-04-22 13:47:37 +0000
tarfs.5: Provide some guidance on zstd frame sizes
Reviewed by: des, emaste
MFC after: 2 weeks
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D44636
(cherry picked from commit fd56d24725860a3c1f12180cf8503d38d8d0c70d)
---
share/man/man5/tarfs.5 | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/share/man/man5/tarfs.5 b/share/man/man5/tarfs.5
index 5378491b9c9f..56c56ac43287 100644
--- a/share/man/man5/tarfs.5
+++ b/share/man/man5/tarfs.5
@@ -74,6 +74,15 @@ to create the tar file, this can be achieved using the
and
.Cm ztsd:frame-per-file
options.
+Sensible frame sizes are powers of 2 between the system's base page size
+(see
+.Xr arch 7 )
+and the value of the
+.Sy kern.maxphys
+sysctl.
+Smaller frames will generally yield a worse compression ratio and require extra
+kernel memory to maintain an index, and larger frames will on average require
+more CPU time to access data when performing random I/O.
.Sh DIAGNOSTICS
If enabled by the
.Dv TARFS_DEBUG
