Commit df8c841d authored by Bagas Sanjaya's avatar Bagas Sanjaya Committed by Chuck Lever
Browse files

NFSD: nfsd-io-modes: Separate lists 



Sphinx reports htmldocs indentation warnings:

Documentation/filesystems/nfs/nfsd-io-modes.rst:58: ERROR: Unexpected indentation. [docutils]
Documentation/filesystems/nfs/nfsd-io-modes.rst:59: WARNING: Block quote ends without a blank line; unexpected unindent. [docutils]

These caused the lists to be shown as long running paragraphs merged
with their previous paragraphs.

Fix these by separating the lists with a blank line.

Fixes: fa8d4e67 ("NFSD: add Documentation/filesystems/nfs/nfsd-io-modes.rst")
Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20251202152506.7a2d2d41@canb.auug.org.au/


Signed-off-by: default avatarBagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Reviewed-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Tested-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 4fcf9952

Documentation/filesystems/nfs/nfsd-io-modes.rst

+5 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ to override that default to use either DONTCACHE or DIRECT IO modes. 


Experimental NFSD debugfs interfaces are available to allow the NFSD IO

mode used for READ and WRITE to be configured independently. See both:



- /sys/kernel/debug/nfsd/io_cache_read

- /sys/kernel/debug/nfsd/io_cache_write
@@ -20,6 +21,7 @@ The default value for both io_cache_read and io_cache_write reflects 
NFSD's default IO mode (which is NFSD_IO_BUFFERED=0).



Based on the configured settings, NFSD's IO will either be:



- cached using page cache (NFSD_IO_BUFFERED=0)

- cached but removed from page cache on completion (NFSD_IO_DONTCACHE=1)

- not cached stable_how=NFS_UNSTABLE (NFSD_IO_DIRECT=2)
@@ -56,6 +58,7 @@ because the page cache will eventually become a bottleneck to servicing 
new IO requests.



For more context on DONTCACHE, please see these Linux commit headers:



- Overview:  9ad6344568cc3 ("mm/filemap: change filemap_create_folio()

  to take a struct kiocb")

- for READ:  8026e49bff9b1 ("mm/filemap: add read support for
@@ -87,7 +90,9 @@ be made. 
The performance win associated with using NFSD DIRECT was previously

discussed on linux-nfs, see:

https://lore.kernel.org/linux-nfs/aEslwqa9iMeZjjlV@kernel.org/



But in summary:



- NFSD DIRECT can significantly reduce memory requirements

- NFSD DIRECT can reduce CPU load by avoiding costly page reclaim work

- NFSD DIRECT can offer more deterministic IO performance