Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751917AbaBHRIm (ORCPT ); Sat, 8 Feb 2014 12:08:42 -0500 Received: from mail-pa0-f50.google.com ([209.85.220.50]:44241 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751453AbaBHRIj (ORCPT ); Sat, 8 Feb 2014 12:08:39 -0500 Message-ID: <1391879318.10160.108.camel@edumazet-glaptop2.roam.corp.google.com> 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] From: Eric Dumazet To: Thomas Glanzmann Cc: John Ogness , Eric Dumazet , "David S. Miller" , "Nicholas A. Bellinger" , target-devel , Linux Network Development , LKML Date: Sat, 08 Feb 2014 09:08:38 -0800 In-Reply-To: <20140208165732.GB22359@glanzmann.de> References: <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> <20140208141905.GG20512@glanzmann.de> <1391869805.10160.97.camel@edumazet-glaptop2.roam.corp.google.com> <20140208150001.GI20512@glanzmann.de> <1391871986.10160.105.camel@edumazet-glaptop2.roam.corp.google.com> <20140208165732.GB22359@glanzmann.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2014-02-08 at 17:57 +0100, Thomas Glanzmann wrote: > Hello Eric, > > > Note : We did some patches in the MSG_MORE logic for sendpage(), but > > in your case I do not think its related > > (git grep -n MSG_SENDPAGE_NOTLAST ) if you are curious > > thank you for the pointer. The iSCSI target code actually uses sendpage > whenever it can. Yep, but the problem (at least on your pcap), is about sending the 48 bytes headers in TCP segment of its own, then the 512 byte payload in a separate segment. I suspect the sendpage() is only used for the payload. No need for MSG_MORE here. The MSG_MORE would need to be set on the first part (48 bytes header), so that TCP stack will defer the push of the segment at the time the 512 bytes payload is added. -- 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/