Managing NFS and KRPC Kernel Configurations in HP-UX 11i v3 (762807-002, June 2014)

2.2.4 nfs3_do_readdirplus
Description
The nfs3_do_readdirplus tunable controls the NFSv3 READDIRPLUS functionality on the
NFS server. In NFS-mounted filesystems, performance of some applications that read huge
directories suffers if they use READDIRPLUS instead of READDIR. These applications do not
require the extended attribute information returned by READDIRPLUS. Usage of READDIR
by these applications can result in a performance improvement.
Tested Values
Default: 1 (READDIRPLUS functionality
is enabled) Min: 0 (READDIRPLUS
functionality is disabled) Max: 1
Restrictions on Changing
The nfs3_do_readdirplus tunable is dynamic. System reboot is not required to activate
changes made to this tunable. Only NFSv3 mount points are affected by changing the
value of this tunable.
Modifying the Value
To disable the READDIRPLUS functionality, disable the tunable. Once disabled, the NFS
client reverts to the READDIR operation to retrieve directory contents and the LOOKUP
operation to retrieve extended attributes. For example, if the READDIRPLUS functionality
is disabled, commands such as ls which display only the directory information, can
have a shorter response time. Commands such as find which displays inode numbers
and attribute data, can have a longer response time.
If applications require both inode numbers and attribute data, enable the tunable.
2.2.5 nfs3_srv_read_copyavoid
Description
When servicing read requests from NFS clients, the server will make separate copies of
the read data in kernel memory multiple times as part of processing each request. HP
recently identified one of these in-memory copies as being unnecessary, and by
eliminating this additional copy the performance of servicing read requests increases. The
nfs3_srv_read_copyavoid tunable controls whether the NFSv3 server will avoid this
unnecessary in-memory copy or continue using the standard read logic.
The nfs2_srv_read_copyavoid tunable controls the server-side read copy avoidance feature
for NFSv2 filesystems. For more information on this tunable, see nfs2_srv_read_copyavoid.
Tested Values
Default: 0 (Server-side read copy avoidance feature is
disabled) Min: 0
Max: 1 (Server-side read copy avoidance
feature is enabled)