From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751579AbWDOHep (ORCPT ); Sat, 15 Apr 2006 03:34:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751577AbWDOHep (ORCPT ); Sat, 15 Apr 2006 03:34:45 -0400 Received: from dsl027-180-168.sfo1.dsl.speakeasy.net ([216.27.180.168]:45721 "EHLO sunset.davemloft.net") by vger.kernel.org with ESMTP id S1751573AbWDOHeo (ORCPT ); Sat, 15 Apr 2006 03:34:44 -0400 Date: Sat, 15 Apr 2006 00:34:57 -0700 (PDT) Message-Id: <20060415.003457.103031290.davem@davemloft.net> To: heiko.carstens@de.ibm.com Cc: shemminger@osdl.org, jgarzik@pobox.com, akpm@osdl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, fpavlic@de.ibm.com, davem@sunset.davemloft.net Subject: Re: [patch] ipv4: initialize arp_tbl rw lock From: "David S. Miller" In-Reply-To: <20060415072745.GA17011@osiris.boeblingen.de.ibm.com> References: <20060408100213.GA9412@osiris.boeblingen.de.ibm.com> <20060408.031404.111884281.davem@davemloft.net> <20060415072745.GA17011@osiris.boeblingen.de.ibm.com> X-Mailer: Mew version 4.2.53 on Emacs 21.4 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Heiko Carstens Date: Sat, 15 Apr 2006 09:27:45 +0200 > Tried to figure out what is causing the delays I experienced when I replaced > module_init() in af_inet.c with fs_initcall(). After all it turned out that > synchronize_net() which is basicically nothing else than synchronize_rcu() > sometimes takes several seconds to complete?! No idea why that is... > > callchain: inet_init() -> inet_register_protosw() -> synchronize_net() The problem can't be rcu_init(), that gets done very early in init/main.c Maybe it's some timer or something else specific to s390? It could also be that there's perhaps nothing to context switch to, thus the RCU takes forever to "happen".