From: Shesha@asu.edu
To: linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org
Subject: Why throughput increases as MTU size is increased
Date: Wed, 30 Apr 2003 07:10:04 -0700 (MST) [thread overview]
Message-ID: <Pine.GSO.4.21.0304300706400.28571-100000@general2.asu.edu> (raw)
Hi All,
I have a question which I am not able to answer myself.I request you all to
give
me some input.
When I measure the performance of iSCSI on XScale with MTU size = 1500 bytes,
a throughput of 32 Mbps was observed. As the MTU size was increased, the
throughput also increased.
1500 -> 32 Mbps
3000 -> 56
4500 -> 80
6000 -> 100
7500 -> 108
9000 -> 108
Actually the throughput saturates. I thought, the per-packet overhead
decreases as the MTU
size increases. This contributes to the performance improvement. And the
saturation is achieved because, the iSCSI max PDU size is 8k. Even if
we increase the MTU size beyond 8k, we will not see any change because,
iSCSI
devivers a max of 8K PDU to TCP. Therefore a saturation in throughput is
observed.
But the question is, Am I thinking correctly?
secondly, if yes,does the per-packet over head decrease the performance so
much. we are observing, somewhere like 4 times improvement in throughput. Can
there be any other reason for this observation.
Thanking you
Shesha
next reply other threads:[~2003-04-30 13:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-04-30 14:10 Shesha [this message]
2003-04-30 15:30 ` Why throughput increases as MTU size is increased Stephen Satchell
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