Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934462AbWK2X3e (ORCPT ); Wed, 29 Nov 2006 18:29:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S935044AbWK2X3e (ORCPT ); Wed, 29 Nov 2006 18:29:34 -0500 Received: from mailgw1.fnal.gov ([131.225.111.11]:34750 "EHLO mailgw1.fnal.gov") by vger.kernel.org with ESMTP id S934638AbWK2X3c (ORCPT ); Wed, 29 Nov 2006 18:29:32 -0500 Date: Wed, 29 Nov 2006 17:29:27 -0600 From: Wenji Wu Subject: [patch 2/4] - Potential performance bottleneck for Linxu TCP In-reply-to: To: netdev@vger.kernel.org, davem@davemloft.net, akpm@osdl.org, linux-kernel@vger.kernel.org Reply-to: wenji@fnal.gov Message-id: MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) Content-type: multipart/mixed; boundary="Boundary_(ID_wvR+8WWOia3zqV21TjrsPg)" Importance: Normal X-Priority: 3 (Normal) X-MSMail-priority: Normal Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2004 Lines: 59 This is a multi-part message in MIME format. --Boundary_(ID_wvR+8WWOia3zqV21TjrsPg) Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7BIT From: Wenji Wu Greetings, For Linux TCP, when the network applcaiton make system call to move data from socket's receive buffer to user space by calling tcp_recvmsg(). The socket will be locked. During the period, all the incoming packet for the TCP socket will go to the backlog queue without being TCP processed. Since Linux 2.6 can be inerrupted mid-task, if the network application expires, and moved to the expired array with the socket locked, all the packets within the backlog queue will not be TCP processed till the network applicaton resume its execution. If the system is heavily loaded, TCP can easily RTO in the Sender Side. Attached is the patch 2/4 best regards, wenji Wenji Wu Network Researcher Fermilab, MS-368 P.O. Box 500 Batavia, IL, 60510 (Email): wenji@fnal.gov (O): 001-630-840-4541 --Boundary_(ID_wvR+8WWOia3zqV21TjrsPg) Content-type: application/octet-stream; name=sched.h.patch Content-transfer-encoding: QUOTED-PRINTABLE Content-disposition: attachment; filename=sched.h.patch --- linux-2.6.14-old/include/linux/sched.h=092006-11-29 16:25:42.0000= 00000 -0600=0A+++ linux-2.6.14/include/linux/sched.h=092006-11-29 10:= 32:55.000000000 -0600=0A@@ -813,6 +813,9 @@=0A =09int cpuset_mems_gen= eration;=0A #endif=0A =09atomic_t fs_excl;=09/* holding fs exclusive = resources */=0A+=09int backlog_flag; =09/* packets wait in tcp backlo= g queue flag */=0A+=09int extrarun_flag;=09/* extra run flag for TCP = performance */=0A+=0A };=0A =0A static inline pid_t process_group(str= uct task_struct *tsk)=0A= --Boundary_(ID_wvR+8WWOia3zqV21TjrsPg)-- - 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/