From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: [RFC] tcp: use order-3 pages in tcp_sendmsg() Date: Thu, 20 Sep 2012 13:06:22 -0700 Message-ID: <505B773E.9070501@hp.com> References: <1348119475.31352.60.camel@edumazet-glaptop> <505B4E13.5000501@hp.com> <20120920.154007.1073423645697694793.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: eric.dumazet@gmail.com, subramanian.vijay@gmail.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from g5t0007.atlanta.hp.com ([15.192.0.44]:43040 "EHLO g5t0007.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754870Ab2ITUGY (ORCPT ); Thu, 20 Sep 2012 16:06:24 -0400 In-Reply-To: <20120920.154007.1073423645697694793.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 09/20/2012 12:40 PM, David Miller wrote: > From: Rick Jones > Date: Thu, 20 Sep 2012 10:10:43 -0700 > >> On 09/19/2012 10:37 PM, Eric Dumazet wrote: >>> loopback is lossless, so its always surprising we can have TCP >>> retransmits on this medium ;) >> >> Is it lossless? >> >> raj@tardy:~/netperf2_trunk$ netstat -s | grep pru >> 19 packets pruned from receive queue because of socket buffer overrun > > Those packets are not being dropped by the loopback device. > Yes, I was being too fast and loose with my wording, paying more attention to the netperf tests than the rest of it. While loopback may be lossless, TCP retransmissions over loopback shouldn't be all *that* surprising. rick