From: Stephen Hemminger <shemminger@osdl.org>
To: "Injong Rhee" <rhee@eos.ncsu.edu>
Cc: "Sangtae Ha" <sha2@ncsu.edu>, <netdev@vger.kernel.org>
Subject: Re: TCP congestion graphs
Date: Wed, 25 Oct 2006 18:30:25 -0700 [thread overview]
Message-ID: <20061025183025.7c4f9d66@localhost.localdomain> (raw)
In-Reply-To: <000701c6f885$b57aa390$4a580e98@ncsu2cc0c3fa00>
On Wed, 25 Oct 2006 18:34:17 -0400
"Injong Rhee" <rhee@eos.ncsu.edu> wrote:
> Not sure why the slow start for cubic is slower than the others.
> We will check on this.
>
I think it is because cubic initializes with a ssthresh of 100,
and others leave ssthresh uninitialized until the first loss.
This causes cubic to change to conservative mode once it crosses
the initial ssthresh. Other protocols just keep doing additive
increase.
My large BDP test has a 500ms delay (250ms each way) and a real
100mbit link on the last hop.
Because the intermediate emulator has a large queue (10,000 packets)
large growth is possible before the first loss event. There were also
no other flows during this test to fill the intermediate queue.
This may very well be a bogus test, I just was looking for large
BDP behavior quirks. Any test without background traffic as you
have argued is unrealistic.
next prev parent reply other threads:[~2006-10-26 1:30 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-25 18:02 TCP congestion graphs Stephen Hemminger
2006-10-25 22:34 ` Injong Rhee
2006-10-26 1:30 ` Stephen Hemminger [this message]
2006-10-26 18:50 ` Hagen Paul Pfeifer
2006-10-26 19:36 ` Stephen Hemminger
2006-10-31 20:00 ` TCP congestion graphs (2.6.19-rc4) Stephen Hemminger
2006-10-31 23:25 ` Xiaoliang (David) Wei
2006-11-01 0:10 ` Stephen Hemminger
2006-11-01 1:30 ` David Miller
2006-11-01 5:25 ` Evgeniy Polyakov
2006-11-01 5:58 ` Stephen Hemminger
2006-11-02 5:44 ` David Miller
2006-11-02 19:58 ` Stephen Hemminger
2006-11-28 22:38 ` David Miller
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