From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: TCP CUBIC and IPoIB
Date: Mon, 8 Nov 2010 17:58:13 -0700 [thread overview]
Message-ID: <20101109005813.GD909@obsidianresearch.com> (raw)
I wonder if anyone has ever looked at this? It looks like there is
something wrong here.
I was just looking at some results from a stock 2.6.35 kernel doing
TCP over IPoIB (2k MTU) and CUBIC looks like it is going nutz, you can
see in a bandwidth plot a fairly characteristic saw tooth pattern, and
diminished bandwidth. The effect compounds rather dramatically as the
RTT goes up.
This isn't really my area of expertise, so I wonder if someone else
has looked into this? Errant congestion events will sap bandwidth
even on low latency links..
Cheers,
Jason
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reply other threads:[~2010-11-09 0:58 UTC|newest]
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