From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next-2.6] net: dont hold rtnl mutex during netlink dump callbacks Date: Mon, 02 May 2011 15:27:33 -0700 (PDT) Message-ID: <20110502.152733.48516094.davem@davemloft.net> References: <1303980967.3360.60.camel@edumazet-laptop> <20110428084337.6b54603e@nehalam> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: eric.dumazet@gmail.com, kaber@trash.net, netdev@vger.kernel.org, remi.denis-courmont@nokia.com To: shemminger@vyatta.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:56911 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757245Ab1EBW2H (ORCPT ); Mon, 2 May 2011 18:28:07 -0400 In-Reply-To: <20110428084337.6b54603e@nehalam> Sender: netdev-owner@vger.kernel.org List-ID: From: Stephen Hemminger Date: Thu, 28 Apr 2011 08:43:37 -0700 > On Thu, 28 Apr 2011 10:56:07 +0200 > Eric Dumazet wrote: > >> Four years ago, Patrick made a change to hold rtnl mutex during netlink >> dump callbacks. >> >> I believe it was a wrong move. This slows down concurrent dumps, making >> good old /proc/net/ files faster than rtnetlink in some situations. >> >> This occurred to me because one "ip link show dev ..." was _very_ slow >> on a workload adding/removing network devices in background. >> >> All dump callbacks are able to use RCU locking now, so this patch does >> roughly a revert of commits : >> >> 1c2d670f366 : [RTNETLINK]: Hold rtnl_mutex during netlink dump callbacks >> 6313c1e0992 : [RTNETLINK]: Remove unnecessary locking in dump callbacks >> >> This let writers fight for rtnl mutex and readers going full speed. >> >> It also takes care of phonet : phonet_route_get() is now called from rcu >> read section. I renamed it to phonet_route_get_rcu() >> >> Signed-off-by: Eric Dumazet >> Cc: Patrick McHardy >> Cc: Remi Denis-Courmont > > Acked-by: Stephen Hemminger Applied, thanks everyone!