UDP buffer tuning

[Dimitry_1]

Hi,

I have Oracle 9i RAC problem which points to UDP buffer parameter tuning on the system.

I have read about the subject and found two paramters that affect the operations.

They are :

udp_recv_hiwater_max - Upper bound on UDP receive buffer size
Currently set at 2 GB
socket_udp_rcvbuf_default - Sets the default receive buffer size for socket
Currently set at 65535.


I would like to get a better understanding of how the two differ . Is one a hard limit of all UDP receive queues and the other is for each socket?

I would appreciate some more useful info. Also, if anyone can relate UDP buffer tuning to Oracle, I would appreciate it greatly.

Dimitry.

[Sathya Sastry]

Hi Dimitry

Does this has sufficient info you were looking for?

socket_udp_sndbuf_default:

Sets the default send buffer size for UDP sockets.
[1-65535] Default: 65535

socket_udp_rcvbuf_default:

Sets the default receive buffer size for UDP sockets.
The value of this tunable parameter should not exceed the
value of the ndd parameter udp_recv_hiwater_max. Otherwise,
a socket() call to create UDP socket will fail and return
the errno value EINVAL.
[1-2147483647] Default: 65535

udp_recv_hiwater_max:

Limits the receive buffer size for TCP and UDP sockets or
communication endpoints specified in a SO_RCVBUF option of a
setsockopt() call or XTI_RCVBUF option in a t_optmgmt() call.

A setsockopt() call with a SO_RCVBUF option that exceeds the
corresponding kernel parameter value will fail and return the
errno value EINVAL.

A t_optmgmt() call with an XIT_RCVBUF option that exceeds the
corresponding kernel parameter value will fail and return the
t_errno value TBADOPT.

A socket() call to create a UDP socket will fail and return
the errno value EINVAL if the value of the ndd parameter
socket_udp_rcvbuf_default exceeds the value of udp_recv_hiwater_max
[1024-2147483647] Default: 2147483647 bytes