[RFC PATCH 5/5] fuse: add documentation of sysfs parameter to limitmaximum fuse request size

[Mitsuo Hayasaka]

Add an explantion about the sysfs parameter to the limit
maximum read/write request size.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@xxxxxxxxxxx>
Cc: Rob Landley <rob@xxxxxxxxxxx>
Cc: Miklos Szeredi <miklos@xxxxxxxxxx>
---

 Documentation/filesystems/fuse.txt |   17 ++++++++++++++++-
 1 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/Documentation/filesystems/fuse.txt b/Documentation/filesystems/fuse.txt
index 13af4a4..e6ffba3 100644
--- a/Documentation/filesystems/fuse.txt
+++ b/Documentation/filesystems/fuse.txt
@@ -108,13 +108,28 @@ Mount options
 
   With this option the maximum size of read operations can be set.
   The default is infinite.  Note that the size of read requests is
-  limited anyway to 32 pages (which is 128kbyte on i386).
+  limited to 32 pages (which is 128kbyte on i386) if direct_io
+  option is not specified. When direct_io option is specified,
+  the request size is limited to max_pages_per_req sysfs parameter.
 
 'blksize=N'
 
   Set the block size for the filesystem.  The default is 512.  This
   option is only valid for 'fuseblk' type mounts.
 
+Sysfs parameter
+~~~~~~~~~~~~~~~
+
+The sysfs parameter max_pages_per_req limits the maximum page size per
+FUSE request.
+
+	/sys/fs/fuse/max_pages_per_req
+
+The default is 32 pages. It can be changed from 32 to 256 pages, which
+may improve the read/write throughput optimizing it. This change is
+effective per mount. Therefore, the re-mounting of FUSE filesystem
+is required after changing it.
+
 Control filesystem
 ~~~~~~~~~~~~~~~~~~
 

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