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From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: dave.taht@gmail.com, jg@freedesktop.org, shemminger@vyatta.com,
	jch@pps.jussieu.fr, nichols@pollere.com, netdev@vger.kernel.org
Subject: Re: BQL + Basic Latency under load results - 100Mbit, GSO/TSO off, pfifo_fast vs SFQ vs QFQ
Date: Tue, 03 Jan 2012 12:52:37 -0500 (EST)	[thread overview]
Message-ID: <20120103.125237.6858695266751093.davem@davemloft.net> (raw)
In-Reply-To: <1325478811.2526.10.camel@edumazet-laptop>

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 02 Jan 2012 05:33:31 +0100

> [PATCH net-next] sch_sfq: dont put new flow at the end of flows
> 
> SFQ enqueue algo puts a new flow _behind_ all pre-existing flows in the
> circular list. In fact this is probably an old SFQ implementation bug.
> 
> 100 Mbits = ~8333 full frames per second, or ~8 frames per ms.
> 
> With 50 flows, it means your "new flow" will have to wait 50 packets
> being sent before its own packet. Thats the ~6ms.
> 
> We certainly can change SFQ to give a priority advantage to new flows,
> so that next dequeued packet is taken from a new flow, not an old one.
> 
> Reported-by: Dave Taht <dave.taht@gmail.com>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied, thanks Eric.

      parent reply	other threads:[~2012-01-03 17:52 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAA93jw6r45zBn4p76R9-2UNdp=OM+uiYqPKcKnjqBReR_oh1BA@mail.gmail.com>
     [not found] ` <CAA93jw5JjVBQOFL=td55rOpXbUYc=uT_rjeY04O137g_-tBJHw@mail.gmail.com>
     [not found]   ` <CAA93jw7bLnHtVnZGN5wVPQZc46XT_B--cY1ocUbnm1AS=J_YHw@mail.gmail.com>
2012-01-02  4:33     ` BQL + Basic Latency under load results - 100Mbit, GSO/TSO off, pfifo_fast vs SFQ vs QFQ Eric Dumazet
2012-01-02  4:55       ` Eric Dumazet
2012-01-02  5:07         ` Eric Dumazet
2012-01-02  5:27           ` Eric Dumazet
2012-01-03 17:52       ` David Miller [this message]

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