Poor implementation of TCP/IP or RPC on a SUN3/60 running SUNOS-4.0?

[Stephen X. Nahm]

In article <8905101313.AA04157 at iesd.dk> in Sun-Spots-Digest:  Volume 7,
Issue 304, ruseng at iesd.dk (Carsten Ruseng Jakobsen) writes:

>While evaluating the performance of SUN-RPC, I detected the TCP protocol
>slowing dramatical down when sending packets with sizes close to the
>magical 4096 and 8192 bytes.

I've emailed Carsten previously, but I'm posting here for the information
of those reading this list.  The performance anomalies reported are a
result of the default buffer sizes used by the RPC library.  The buffer
sizes can be changed by the user as described below:

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>From sxn Wed May 17 12:04:07 1989
To: ruseng at iesd.dk
Subject: Re:  Elbows in RPC/TCP performance

You can fix things by setting the "send_buf_size" and/or "recv_buf_size"
parameters of clnttcp_create() and svctcp_create().  For your example, where
the client sends big packets and gets back small acks, use:

	remote = clnttcp_create(&sin, YOURPROG, YOURVERS, &sock, 24000, 0);

(where sock can be RPC_ANYSOCK, and sin is set correctly.)

For the server side, which is receiving big packets and sending back small
acks, use:

	transp = svctcp_create(RPC_ANYSOCK, 0, 24000);

I set up an RPC program that repeated your scenario.  Before I made the
above changes, I got similar results as you got.  After I adjusted the
appropriate parameters correctly (and without any setsockopt
manipulation), I got:

Size: 0 time: 0.94 Seconds
Size: 512       time: 0.97 Seconds
Size: 1024      time: 1.16 seconds
Size: 2048      time: 1.50 Seconds
Size: 4000      time: 1.99 Seconds
Size: 4096      time: 2.28 seconds
Size: 8000      time: 3.37 Seconds
Size: 8192      time: 3.81 seconds
Size: 8300      time: 3.70 seconds
Size: 16300     time: 6.30 Seconds
Size: 16392     time: 8.72 seconds
Size: 16400     time: 10.54 seconds

See rpc(3) in the SunOS manual, or in the RPCSRC 4.0 man directory.

Steve Nahm

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-- 
Steve Nahm                              sxn at sun.COM or sun!sxn