Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751763AbaBHOTK (ORCPT ); Sat, 8 Feb 2014 09:19:10 -0500 Received: from infra.glanzmann.de ([88.198.249.254]:60816 "EHLO infra.glanzmann.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751170AbaBHOTI (ORCPT ); Sat, 8 Feb 2014 09:19:08 -0500 Date: Sat, 8 Feb 2014 15:19:05 +0100 From: Thomas Glanzmann To: Eric Dumazet Cc: John Ogness , Eric Dumazet , "David S. Miller" , "Nicholas A. Bellinger" , target-devel , Linux Network Development , LKML Subject: Re: 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] Message-ID: <20140208141905.GG20512@glanzmann.de> Mail-Followup-To: Eric Dumazet , John Ogness , Eric Dumazet , "David S. Miller" , "Nicholas A. Bellinger" , target-devel , Linux Network Development , LKML References: <1391727771.14985.41.camel@haakon3.risingtidesystems.com> <20140207051500.GB10916@glanzmann.de> <20140207075536.GB17815@glanzmann.de> <1391801597.1155.28.camel@haakon3.risingtidesystems.com> <20140207205142.GA8609@glanzmann.de> <20140208093808.GD16336@glanzmann.de> <1391865273.10160.76.camel@edumazet-glaptop2.roam.corp.google.com> <1391866389.10160.80.camel@edumazet-glaptop2.roam.corp.google.com> <1391867404.10160.88.camel@edumazet-glaptop2.roam.corp.google.com> <1391868816.10160.93.camel@edumazet-glaptop2.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1391868816.10160.93.camel@edumazet-glaptop2.roam.corp.google.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Eric, > > BTW this problem demonstrates there is room for improvement in iCSCI, > > using MSG_MORE to avoid sending two small segments in separate frames. > With the fix, new pcap is more explicit about this suboptimal behavior : > 05:34:16.280900 IP 10.101.0.13.41531 > 10.101.99.5.3260: Flags [.], ack 54353, win 514, options [nop,nop,TS val 1732452 ecr 4294935370], length 0 > 05:34:16.280949 IP 10.101.0.13.41531 > 10.101.99.5.3260: Flags [P.], seq 5328:5376, ack 54353, win 514, options [nop,nop,TS val 1732452 ecr 4294935370], length 48 > 05:34:16.280982 IP 10.101.99.5.3260 > 10.101.0.13.41531: Flags [P.], seq 54353:54401, ack 5376, win 235, options [nop,nop,TS val 4294935370 ecr 1732452], length 48 > 05:34:16.281000 IP 10.101.99.5.3260 > 10.101.0.13.41531: Flags [P.], seq 54401:54913, ack 5376, win 235, options [nop,nop,TS val 4294935370 ecr 1732452], length 512 > 05:34:16.281107 IP 10.101.0.13.41531 > 10.101.99.5.3260: Flags [.], ack 54913, win 514, options [nop,nop,TS val 1732452 ecr 4294935370], length 0 > 05:34:16.281157 IP 10.101.0.13.41531 > 10.101.99.5.3260: Flags [P.], seq 5376:5424, ack 54913, win 514, options [nop,nop,TS val 1732452 ecr 4294935370], length 48 > 05:34:16.281190 IP 10.101.99.5.3260 > 10.101.0.13.41531: Flags [P.], seq 54913:54961, ack 5424, win 235, options [nop,nop,TS val 4294935370 ecr 1732452], length 48 > 05:34:16.281208 IP 10.101.99.5.3260 > 10.101.0.13.41531: Flags [P.], seq 54961:55473, ack 5424, win 235, options [nop,nop,TS val 4294935370 ecr 1732452], length 512 > 05:34:16.281337 IP 10.101.0.13.41531 > 10.101.99.5.3260: Flags [.], ack 55473, win 514, options [nop,nop,TS val 1732452 ecr 4294935370], length 0 > 05:34:16.281390 IP 10.101.0.13.41531 > 10.101.99.5.3260: Flags [P.], seq 5424:5472, ack 55473, win 514, options [nop,nop,TS val 1732452 ecr 4294935370], length 48 > 05:34:16.281423 IP 10.101.99.5.3260 > 10.101.0.13.41531: Flags [P.], seq 55473:55521, ack 5472, win 235, options [nop,nop,TS val 4294935370 ecr 1732452], length 48 > 05:34:16.281440 IP 10.101.99.5.3260 > 10.101.0.13.41531: Flags [P.], seq 55521:56033, ack 5472, win 235, options [nop,nop,TS val 4294935370 ecr 1732452], length 512 I get the idea. However I'm a little bit confused, when I do a 'git grep MSG_MORE' I don't see much references in the Linux kernel who use it at all. So do you have an example for me where this flags needs to be applied? Cheers, Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/