SGI 905314 (2/2): document constraints on client transfer size
Subsystems (2)
PATCH 1/1 SGI 905314 (2/2): document constraints on client transfer size
G'day,
SGI bug #905314
This patch adds a comment documenting the actual constraints on NFS_MAX_FILE_IO_BUFFER_SIZE for the next guy who needs to know ;-)
--- /usr/tmp/TmpDir.28396-0/linux/linux/include/linux/nfs_fs.h_1.21 Fri Nov 28
23:07:47 2003
+++ linux/include/linux/nfs_fs.h Fri Nov 28 21:55:30 2003
@@ -40,6 +40,18 @@
*/
#define NFS_MAX_DIRCACHE 16
+/*
+ * NFS_MAX_FILE_IO_BUFFER_SIZE limits the rsize and wsize that
+ * userspace can request in mount options (note that the server
+ * also gives us a limit in response to the FSINFO call). The
+ * value is constrained by 1) has to fit in a UDP datagram less
+ * some headers 2) has to be a multiple of page size 3) has to
+ * be no more than NFS_READ_MAXIOV=8 pages for rsize, and
+ * NFS_WRITE_MAXIOV=8 pages for wsize and 4) has to be a power
+ * of two (actually this is bogus but nfs_read_super relies on it).
+ * For best performance we usually want the largest value
+ * consistent with these constraints.
+ */
#define NFS_MAX_FILE_IO_BUFFER_SIZE 32768
#define NFS_DEF_FILE_IO_BUFFER_SIZE 4096
Greg.
Signature · 12 lines
Greg Banks, R&D Software Engineer, SGI Australian Software Group. I don't speak for SGI. ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ NFS maillist - [email protected] https://lists.sourceforge.net/lists/listinfo/nfs