From owner-freebsd-net@FreeBSD.ORG Sat Aug 9 20:22:08 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 2D4B97D1 for ; Sat, 9 Aug 2014 20:22:08 +0000 (UTC) Received: from mail-la0-x22a.google.com (mail-la0-x22a.google.com [IPv6:2a00:1450:4010:c03::22a]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id A9C7A24C3 for ; Sat, 9 Aug 2014 20:22:07 +0000 (UTC) Received: by mail-la0-f42.google.com with SMTP id pv20so5685761lab.29 for ; Sat, 09 Aug 2014 13:22:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=oH0/t8WR+vNMNGhB8RwR0NYsdx/WUNpYm1t0sp9Ltik=; b=R+9py5J9sMZi88lEznbBVdm16L3oW3LZusl27KnYAlWxEvQGcg4ih9r52PSHSf9GZq sjb+P6nCz9iDV0Rw/DYQDRh4ZSbKTp/4GBLIOniWdZ4ZXgoh0KaDk6jUFqK5Y5mXmzU/ +lNhRnZ6BOzonGUSvd4yk54Sys/p2UgUJgf7IjFKvU27rn1q4Ltl0xVKA7/rgxTkZZxM TpqP8qekXge3URcO+Jh83AWY5kYWriexoeZ7D4mk1XTggRJ09UXAHuBliuBQsUZe4T7X xOqbupFaunnzfmZP1Vx0YatH8GQ81OprpJJlC+uVl3Zib/T0SwDmltwpaNu085TY+r3n F2MA== MIME-Version: 1.0 X-Received: by 10.152.8.82 with SMTP id p18mr10518laa.83.1407615725070; Sat, 09 Aug 2014 13:22:05 -0700 (PDT) Received: by 10.114.81.73 with HTTP; Sat, 9 Aug 2014 13:22:05 -0700 (PDT) In-Reply-To: <8AE1AC56-D52F-4F13-AAA3-BB96042B37DD@lurchi.franken.de> References: <20140809184232.GF83475@funkthat.com> <8AE1AC56-D52F-4F13-AAA3-BB96042B37DD@lurchi.franken.de> Date: Sat, 9 Aug 2014 13:22:05 -0700 Message-ID: Subject: Re: A problem on TCP in High RTT Environment. From: hiren panchasara To: Michael Tuexen Content-Type: text/plain; charset=UTF-8 Cc: "freebsd-net@freebsd.org" , John-Mark Gurney , Niu Zhixiong , Bill Yuan X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 09 Aug 2014 20:22:08 -0000 On Sat, Aug 9, 2014 at 12:51 PM, Michael Tuexen wrote: > > On 09 Aug 2014, at 20:42, John-Mark Gurney wrote: > >> Niu Zhixiong wrote this message on Fri, Aug 08, 2014 at 20:34 +0800: >>> Dear all, >>> >>> Last month, I send problems related to FTP/TCP in a high RTT environment. >>> After that, I setup a simulation environment(Dummynet) to test TCP and SCTP >>> in high delay environment. After finishing the test, I can see TCP is >>> always slower than SCTP. But, I think it is not possible. (Plz see the >>> figure in the attachment). When the delay is 200ms(means RTT=400ms). >>> Besides, the TCP is extremely slow. >>> >>> ALL BW=20Mbps, DELAY= 0 ~ 200MS, Packet LOSS = 0 (by dummynet) >>> >>> This is my parameters: >>> FreeBSD vfreetest0 10.0-RELEASE FreeBSD 10.0-RELEASE #0: Thu Aug 7 >>> 11:04:15 HKT 2014 >>> >>> sysctl net.inet.tcp >> >> [...] >> >>> net.inet.tcp.recvbuf_auto: 0 >> >> [...] >> >>> net.inet.tcp.sendbuf_auto: 0 >> >> Try enabling this... This should allow the buffer to grow large enough >> to deal w/ the higher latency... >> >> Also, make sure your program isn't setting the recv buffer size as that >> will disable the auto growing... > I think the program sets the buffer to 2MB, which it also does for SCTP. > So having both statically at the same size makes sense for the comparison. > I remember that there was a bug in the combination of LRO and delayed ACK, > which was fixed, but I don't remember it was fixed before 10.0... If you are thinking of r256920, I believe it did make it into 10.0R. cheers, Hiren