From: Eric Dumazet <eric.dumazet@gmail.com>
To: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Jonathan Davies <Jonathan.Davies@citrix.com>,
"xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>,
Wei Liu <wei.liu2@citrix.com>,
Ian Campbell <Ian.Campbell@citrix.com>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
netdev <netdev@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Eric Dumazet <edumazet@google.com>,
Paul Durrant <paul.durrant@citrix.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
Felipe Franciosi <felipe.franciosi@citrix.com>,
linux-arm-kernel@lists.infradead.org,
David Vrabel <david.vrabel@citrix.com>
Subject: Re: [Xen-devel] "tcp: refine TSO autosizing" causes performance regression on Xen
Date: Wed, 15 Apr 2015 10:41:28 -0700 [thread overview]
Message-ID: <1429119688.7346.123.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <552E9E8D.1080000@eu.citrix.com>
On Wed, 2015-04-15 at 18:23 +0100, George Dunlap wrote:
> Which means that max(2*skb->truesize, sk->sk_pacing_rate >>10) is
> *already* larger for Xen; that calculation mentioned in the comment is
> *already* doing the right thing.
Sigh.
1ms of traffic at 40Gbit is 5 MBytes
The reason for the cap to /proc/sys/net/ipv4/tcp_limit_output_bytes is
to provide the limitation of ~2 TSO packets, which _also_ is documented.
Without this limitation, 5 MBytes could translate to : Fill the queue,
do not limit.
If a particular driver needs to extend the limit, fine, document it and
take actions.
WARNING: multiple messages have this Message-ID (diff)
From: eric.dumazet@gmail.com (Eric Dumazet)
To: linux-arm-kernel@lists.infradead.org
Subject: [Xen-devel] "tcp: refine TSO autosizing" causes performance regression on Xen
Date: Wed, 15 Apr 2015 10:41:28 -0700 [thread overview]
Message-ID: <1429119688.7346.123.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <552E9E8D.1080000@eu.citrix.com>
On Wed, 2015-04-15 at 18:23 +0100, George Dunlap wrote:
> Which means that max(2*skb->truesize, sk->sk_pacing_rate >>10) is
> *already* larger for Xen; that calculation mentioned in the comment is
> *already* doing the right thing.
Sigh.
1ms of traffic at 40Gbit is 5 MBytes
The reason for the cap to /proc/sys/net/ipv4/tcp_limit_output_bytes is
to provide the limitation of ~2 TSO packets, which _also_ is documented.
Without this limitation, 5 MBytes could translate to : Fill the queue,
do not limit.
If a particular driver needs to extend the limit, fine, document it and
take actions.
next prev parent reply other threads:[~2015-04-15 17:41 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-09 15:46 "tcp: refine TSO autosizing" causes performance regression on Xen Stefano Stabellini
2015-04-09 15:46 ` Stefano Stabellini
2015-04-09 15:46 ` Stefano Stabellini
2015-04-09 16:16 ` Eric Dumazet
2015-04-09 16:16 ` Eric Dumazet
2015-04-09 16:36 ` Stefano Stabellini
2015-04-09 16:36 ` Stefano Stabellini
2015-04-09 16:36 ` Stefano Stabellini
2015-04-09 17:07 ` Eric Dumazet
2015-04-09 17:07 ` Eric Dumazet
2015-04-13 10:56 ` [Xen-devel] " George Dunlap
2015-04-13 10:56 ` George Dunlap
2015-04-13 13:38 ` Jonathan Davies
2015-04-13 13:38 ` Jonathan Davies
2015-04-13 13:38 ` Jonathan Davies
2015-04-13 13:49 ` Eric Dumazet
2015-04-13 13:49 ` Eric Dumazet
2015-04-15 13:43 ` George Dunlap
2015-04-15 13:43 ` George Dunlap
2015-04-15 16:38 ` Eric Dumazet
2015-04-15 16:38 ` Eric Dumazet
2015-04-15 16:38 ` Eric Dumazet
2015-04-15 17:23 ` George Dunlap
2015-04-15 17:23 ` George Dunlap
2015-04-15 17:23 ` George Dunlap
2015-04-15 17:29 ` Eric Dumazet
2015-04-15 17:29 ` Eric Dumazet
2015-04-15 17:41 ` George Dunlap
2015-04-15 17:41 ` George Dunlap
2015-04-15 17:41 ` George Dunlap
2015-04-15 17:52 ` Eric Dumazet
2015-04-15 17:52 ` Eric Dumazet
2015-04-15 17:55 ` Rick Jones
2015-04-15 17:55 ` Rick Jones
2015-04-15 18:08 ` Eric Dumazet
2015-04-15 18:08 ` Eric Dumazet
2015-04-15 18:19 ` Rick Jones
2015-04-15 18:19 ` Rick Jones
2015-04-15 18:32 ` Eric Dumazet
2015-04-15 18:32 ` Eric Dumazet
2015-04-15 18:32 ` Eric Dumazet
2015-04-15 20:08 ` [Xen-devel] " Rick Jones
2015-04-15 20:08 ` Rick Jones
2015-04-15 20:08 ` Rick Jones
2015-04-15 18:04 ` George Dunlap
2015-04-15 18:04 ` George Dunlap
2015-04-15 18:04 ` George Dunlap
2015-04-15 18:19 ` Eric Dumazet
2015-04-15 18:19 ` Eric Dumazet
2015-04-16 8:56 ` George Dunlap
2015-04-16 8:56 ` George Dunlap
2015-04-16 8:56 ` George Dunlap
2015-04-16 9:20 ` Daniel Borkmann
2015-04-16 9:20 ` Daniel Borkmann
2015-04-16 9:20 ` Daniel Borkmann
2015-04-16 10:01 ` George Dunlap
2015-04-16 10:01 ` George Dunlap
2015-04-16 10:01 ` George Dunlap
2015-04-16 12:42 ` Eric Dumazet
2015-04-16 12:42 ` Eric Dumazet
2015-04-20 11:03 ` George Dunlap
2015-04-20 11:03 ` George Dunlap
2015-06-02 9:52 ` Wei Liu
2015-06-02 9:52 ` Wei Liu
2015-06-02 9:52 ` Wei Liu
2015-06-02 16:16 ` Eric Dumazet
2015-06-02 16:16 ` Eric Dumazet
2015-04-16 9:22 ` David Laight
2015-04-16 9:22 ` David Laight
2015-04-16 9:22 ` David Laight
2015-04-16 10:57 ` George Dunlap
2015-04-16 10:57 ` George Dunlap
2015-04-16 10:57 ` George Dunlap
2015-04-15 17:41 ` Eric Dumazet [this message]
2015-04-15 17:41 ` Eric Dumazet
2015-04-15 17:58 ` Stefano Stabellini
2015-04-15 17:58 ` Stefano Stabellini
2015-04-15 17:58 ` Stefano Stabellini
2015-04-15 18:17 ` Eric Dumazet
2015-04-15 18:17 ` Eric Dumazet
2015-04-16 4:20 ` Herbert Xu
2015-04-16 4:20 ` Herbert Xu
2015-04-16 4:30 ` Eric Dumazet
2015-04-16 4:30 ` Eric Dumazet
2015-04-16 11:39 ` George Dunlap
2015-04-16 11:39 ` George Dunlap
2015-04-16 11:39 ` George Dunlap
2015-04-16 12:16 ` Eric Dumazet
2015-04-16 12:16 ` Eric Dumazet
2015-04-16 13:00 ` Tim Deegan
2015-04-16 13:00 ` Tim Deegan
2015-04-16 13:00 ` Tim Deegan
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