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List:       aix-l
Subject:    Re: Changing NIC settings on the fly
From:       Zoltán_Vad <zoltan.vad () GMAIL ! COM>
Date:       2005-12-16 20:58:07
Message-ID: 722ca7460512161258j2f062bd1q () mail ! gmail ! com
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Hi Larry,

2005/12/16, Larry Scheetz <LScheetz@aultman.com>:
>
> Well this is causing a major issue.  It is so slow.  The others are showing
> 1000Mbps and full duplex which is utilizing the Gig NIC card.  I can go into

I think there are two main issue why the network performance is slow.
Suppose the cpu speed and memory size is good enough.

First, the NIC speed. In the previous two email answer from Holger and Steven
discuss it perfectly.

Second: verify the network options the tcp/udp related buffer sizes.
The AIX default tcp/udp buffer sizes very low, about 16Kb. In my
experience usually the low buffer size is the reason why network
performance is slow.

At least increase the tcp_sendspace / tcp_recvspace value to 65535 (64K)
or higher 131070 (128K) and then benchmark the network performance.
You will see the difference.

The get current (global) values:
no -a | egrep "tcp_send|tcp_recv"

To increase the values higher:
no -o tcp_sendspace = 65535  ... and so on.

There is a possibility per adapter level network parameter tuning. See the next
commands.
lsattr -El en0
chdev -l en0 -a tcp_recvspace=65535 ...

Cheers, Zoltan
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