From: "David S. Miller" <davem@davemloft.net>
To: mst@mellanox.co.il
Cc: rdreier@cisco.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, openib-general@openib.org,
shemminger@osdl.org
Subject: Re: TSO and IPoIB performance degradation
Date: Wed, 08 Mar 2006 12:53:45 -0800 (PST) [thread overview]
Message-ID: <20060308.125345.89171061.davem@davemloft.net> (raw)
In-Reply-To: <20060308125311.GE17618@mellanox.co.il>
From: "Michael S. Tsirkin" <mst@mellanox.co.il>
Date: Wed, 8 Mar 2006 14:53:11 +0200
> What I was trying to figure out was, how can we re-enable the trick without
> hurting TSO? Could a solution be to simply look at the frame size, and call
> tcp_send_delayed_ack if the frame size is small?
The problem is that this patch helps performance when the
receiver is CPU limited.
The old code would delay ACKs forever if the CPU of the
receiver was slow, because we'd wait for all received
packets to be copied into userspace before spitting out
the ACK. This would allow the pipe to empty, since the
sender is waiting for ACKs in order to send more into
the pipe, and once the ACK did go out it would cause the
sender to emit an enormous burst of data. Both of these
behaviors are highly frowned upon for a TCP stack.
I'll try to look at this some more later today.
next prev parent reply other threads:[~2006-03-08 20:53 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-06 22:34 TSO and IPoIB performance degradation Michael S. Tsirkin
2006-03-06 22:40 ` David S. Miller
2006-03-06 22:50 ` Stephen Hemminger
2006-03-07 3:13 ` Shirley Ma
2006-03-07 21:44 ` Matt Leininger
2006-03-07 21:49 ` Stephen Hemminger
2006-03-07 21:53 ` Michael S. Tsirkin
2006-03-08 0:11 ` Matt Leininger
2006-03-08 0:18 ` David S. Miller
2006-03-08 1:17 ` Roland Dreier
2006-03-08 1:23 ` David S. Miller
2006-03-08 1:34 ` Roland Dreier
2006-03-08 12:53 ` Michael S. Tsirkin
2006-03-08 20:53 ` David S. Miller [this message]
2006-03-09 23:48 ` David S. Miller
2006-03-10 0:10 ` Michael S. Tsirkin
2006-03-10 0:38 ` Michael S. Tsirkin
2006-03-10 7:18 ` David S. Miller
2006-03-10 0:21 ` Rick Jones
2006-03-10 7:23 ` David S. Miller
2006-03-10 17:44 ` Rick Jones
2006-03-20 9:06 ` Michael S. Tsirkin
2006-03-20 9:55 ` David S. Miller
2006-03-20 10:22 ` Michael S. Tsirkin
2006-03-20 10:37 ` David S. Miller
2006-03-20 11:27 ` Michael S. Tsirkin
2006-03-20 11:47 ` Arjan van de Ven
2006-03-20 11:49 ` Lennert Buytenhek
2006-03-20 11:53 ` Arjan van de Ven
2006-03-20 13:35 ` Michael S. Tsirkin
2006-03-20 12:04 ` Michael S. Tsirkin
2006-03-20 15:09 ` Benjamin LaHaise
2006-03-20 18:58 ` Rick Jones
2006-03-20 23:00 ` David S. Miller
2006-04-27 4:13 ` Troy Benjegerdes
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