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From: Thomas Glanzmann <thomas@glanzmann.de>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Nicholas A. Bellinger" <nab@linux-iscsi.org>,
	target-devel <target-devel@vger.kernel.org>,
	Linux Network Development <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tcp: disable auto corking by default
Date: Sat, 8 Feb 2014 17:55:39 +0100	[thread overview]
Message-ID: <20140208165539.GA22359@glanzmann.de> (raw)
In-Reply-To: <1391871850.10160.103.camel@edumazet-glaptop2.roam.corp.google.com>

Hello Eric,

> > Disable auto corking by default

> We should let auto corking on during 3.14 development cycle so that we
> can fix the bugs, and thing of some optimizations.

I agree that leaving it enabled helps to find bugs, however I'm not
happy with the round trip time degradation.

> auto cork gives a strong incentive to applications to use
> TCP_CORK/MSG_MORE to avoid overhead of sending multiple small
> segments.

I agree. But if it breaks the application many people won't be happy,
for example I spend already 5 hours to track it down.

> In the normal case, the extra delay is something like 10 us, so if an
> application is really hit by this delay, its a strong sign it could be
> improved, especially if auto corking is off.

Yes, but 230 micro seconds for others. :-(

> Lets wait the end of 3.14 dev cycle before considering this patch.

I agree.

Btw. I mixed up the pcaps for autocork on and off, so I moved the files
that they know show what they should show.

Cheers,
        Thomas

  reply	other threads:[~2014-02-08 16:55 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20140206153640.GB4103@glanzmann.de>
     [not found] ` <1391727771.14985.41.camel@haakon3.risingtidesystems.com>
     [not found]   ` <20140207051500.GB10916@glanzmann.de>
     [not found]     ` <20140207075536.GB17815@glanzmann.de>
     [not found]       ` <1391801597.1155.28.camel@haakon3.risingtidesystems.com>
     [not found]         ` <20140207205142.GA8609@glanzmann.de>
2014-02-08  9:18           ` REGRESSION f54b311142a92ea2e42598e347b84e1655caf8e3 tcp auto corking slows down iSCSI file system creation by factor of 70 [WAS: 4 TB VMFS creation takes 15 minutes vs 26 seconds] Thomas Glanzmann
2014-02-08  9:19             ` [PATCH] tcp: disable auto corking by default Thomas Glanzmann
2014-02-08 15:04               ` Eric Dumazet
2014-02-08 16:55                 ` Thomas Glanzmann [this message]
2014-02-08 17:12                   ` Eric Dumazet
2014-02-08 17:20                     ` Thomas Glanzmann
2014-02-08  9:23           ` REGRESSION f54b311142a92ea2e42598e347b84e1655caf8e3 tcp auto corking slows down iSCSI file system creation by factor of 70 [WAS: 4 TB VMFS creation takes 15 minutes vs 26 seconds] Thomas Glanzmann
2014-02-08  9:38           ` Thomas Glanzmann
2014-02-08  9:38             ` Thomas Glanzmann
2014-02-08 13:14             ` Eric Dumazet
2014-02-08 13:33               ` Eric Dumazet
2014-02-08 13:38                 ` Thomas Glanzmann
2014-02-08 13:50                 ` Eric Dumazet
2014-02-08 14:13                   ` Eric Dumazet
2014-02-08 14:19                     ` Thomas Glanzmann
2014-02-08 14:30                       ` Eric Dumazet
2014-02-08 15:00                         ` Thomas Glanzmann
2014-02-08 15:06                           ` Eric Dumazet
2014-02-08 16:57                             ` Thomas Glanzmann
2014-02-08 17:08                               ` Eric Dumazet
2014-02-08 17:15                                 ` Thomas Glanzmann
2014-02-08 19:12                                   ` Eric Dumazet
2014-02-08 21:36                                     ` Thomas Glanzmann
2014-02-09  0:15                                       ` Eric Dumazet
2014-02-09  7:45                                         ` Thomas Glanzmann
2014-02-09  7:40                                     ` RFC: Set MSG_MORE in iscsit_fe_sendpage_sg to avoid sending multiple TCP packets instead of one Thomas Glanzmann
2014-02-09  7:42                                       ` [PATCH] This extends tx_data and and iscsit_do_tx_data with the additional parameter flags and avoids sending multiple TCP packets in iscsit_fe_sendpage_sg Eric Dumazet
2014-02-09 12:30                                         ` Eric Dumazet
2014-02-09 15:07                                           ` Thomas Glanzmann
2014-02-10 18:58                                           ` Nicholas A. Bellinger
2014-02-10 20:56                                             ` Thomas Glanzmann
2014-02-10 21:01                                               ` Eric Dumazet
2014-02-10 21:09                                                 ` Eric Dumazet
2014-02-10 21:13                                                   ` Thomas Glanzmann
2014-02-10 21:14                                                 ` Thomas Glanzmann
2014-02-08 13:37               ` REGRESSION f54b311142a92ea2e42598e347b84e1655caf8e3 tcp auto corking slows down iSCSI file system creation by factor of 70 [WAS: 4 TB VMFS creation takes 15 minutes vs 26 seconds] Thomas Glanzmann
2014-02-08 13:53                 ` Eric Dumazet
2014-02-08 13:58                   ` Thomas Glanzmann
2014-02-08 14:09                 ` Eric Dumazet
2014-02-08 14:12                   ` Thomas Glanzmann
2014-02-17 14:08                   ` Thomas Glanzmann
2014-02-17 15:26                     ` Eric Dumazet
2014-02-17 15:32                       ` Thomas Glanzmann
2014-02-17 15:46                         ` Eric Dumazet
2014-02-17 15:46                           ` Thomas Glanzmann

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