Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967352AbWK2XbN (ORCPT ); Wed, 29 Nov 2006 18:31:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934356AbWK2XbN (ORCPT ); Wed, 29 Nov 2006 18:31:13 -0500 Received: from mailgw1.fnal.gov ([131.225.111.11]:3007 "EHLO mailgw1.fnal.gov") by vger.kernel.org with ESMTP id S935044AbWK2XbK (ORCPT ); Wed, 29 Nov 2006 18:31:10 -0500 Date: Wed, 29 Nov 2006 17:31:05 -0600 From: Wenji Wu Subject: [patch 4/4] - 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_li4hDdoClOdbXctA3VlaaA)" 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: 2235 Lines: 61 This is a multi-part message in MIME format. --Boundary_(ID_li4hDdoClOdbXctA3VlaaA) 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 3/4 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_li4hDdoClOdbXctA3VlaaA) Content-type: application/octet-stream; name=fork.c.patch Content-transfer-encoding: QUOTED-PRINTABLE Content-disposition: attachment; filename=fork.c.patch --- linux-2.6.14-old/kernel/fork.c=092006-11-29 16:22:25.000000000 -0= 600=0A+++ linux-2.6.14/kernel/fork.c=092006-11-29 11:23:20.000000000 = -0600=0A@@ -868,7 +868,7 @@=0A *=0A * It copies the registers, and = all the appropriate=0A * parts of the process environment (as per th= e clone=0A- * flags). The actual kick-off is left to the caller.=0A+ = * flags). The actual kick-off is left to the caller.copy_process=0A = */=0A static task_t *copy_process(unsigned long clone_flags,=0A =09= =09=09=09 unsigned long stack_start,=0A@@ -1154,6 +1154,9 @@=0A =09wr= ite_unlock_irq(&tasklist_lock);=0A =09retval =3D 0;=0A =0A+=09p->back= log_flag =3D 0;=0A+=09p->extrarun_flag =3D 0;=0A+=0A fork_out:=0A = =09if (retval)=0A =09=09return ERR_PTR(retval);=0A= --Boundary_(ID_li4hDdoClOdbXctA3VlaaA)-- - 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/