NFS Performance Tuning for HP-UX 11.0 and 11i Systems

nfs performance tuning for hp-ux 11.0 and 11i systems page 49

Notes:

Page 49July 22, 2002

nfsd

How many nfsktcpd kernel threads

service NFS/TCP requests?

• The NUM_NFSD variable has no effect on NFS/TCP

• By default, the NFS server launches a maximum of 10

kernel threads for each NFS/TCP connection it receives

• The threads launched for a specific TCP connection will

only service the requests that arrive on that

connection

• By default, HP NFS/TCP clients only open a single TCP

connection to each NFS server, regardless of the number

of filesystems mounted from the server

The total number of server-side kernel threads running at any given time to handle

inbound NFS/TCP requests is directly related to the number of established

NFS/TCP connections from all clients. By default, the server will launch a

maximum of 10 kernel threads to service requests for each TCP connection. Since

NFS/TCP clients only open a single connection to each NFS server (by default), this

limits the server to using only 10 kernel threads to service requests from any

specific NFS client, regardless of how many NFS filesystems the client mounts from

the server.

Under most conditions the single TCP connection and 10 threads per connection

limits should not be an issue. However, in the case where large, multi-processor

clients are mounting many NFS/TCP filesystems from a single server and

multiplexing large numbers of requests across that connection, these characteristics

could result in a potential bottleneck.

The threads that are launched to service requests for a given NFS/TCP connection

are dedicated to that connection and cannot be used to process inbound requests

on other NFS/TCP connections.