From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755533Ab2CNHmN (ORCPT ); Wed, 14 Mar 2012 03:42:13 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:50481 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751758Ab2CNHmM (ORCPT ); Wed, 14 Mar 2012 03:42:12 -0400 X-IronPort-AV: E=Sophos;i="4.73,582,1325433600"; d="scan'208";a="4532031" Message-ID: <4F604CFA.9010302@cn.fujitsu.com> Date: Wed, 14 Mar 2012 15:47:06 +0800 From: Lai Jiangshan User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.9) Gecko/20100921 Fedora/3.1.4-1.fc14 Thunderbird/3.1.4 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Lai Jiangshan , linux-kernel@vger.kernel.org, mingo@elte.hu, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, fweisbec@gmail.com, patches@linaro.org Subject: Re: [RFC PATCH 5/5 single-thread-version] implement per-domain single-thread state machine call_srcu() References: <1331023359-6987-1-git-send-email-laijs@cn.fujitsu.com> <1331027858-7648-1-git-send-email-laijs@cn.fujitsu.com> <1331027858-7648-4-git-send-email-laijs@cn.fujitsu.com> <4F56DBDA.1020608@cn.fujitsu.com> <20120308203533.GN2348@linux.vnet.ibm.com> <20120312180321.GG2471@linux.vnet.ibm.com> In-Reply-To: <20120312180321.GG2471@linux.vnet.ibm.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-03-14 15:40:04, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-03-14 15:40:08, Serialize complete at 2012-03-14 15:40:08 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/13/2012 02:03 AM, Paul E. McKenney wrote: >> >> In mb()-based srcu, synchronize_srcu() is very fast, >> synchronize_srcu_expedited() makes less sense than before. > > I am worried about expedited callbacks getting backed up behind > non-expedited callbacks (especially given Peter's point about per-VMA > SRCU callbacks) and behind other workqueue uses. > >> But when wait_srcu_gp() is move back here, I will use >> a bigger "trycount" for synchronize_srcu_expedited(). >> >> And any problem for srcu_advance_batches()? > > I prefer the use of "return" that you and Peter discussed later. > > What sort of testing are you doing? > rcutorture in my box for several days on my daily used machine. What would you prefer for next round of patches, single-thread or per-cpu? I will send them soon. (per-cpu approach will be also "batches, in-sleepable, reuse rcu_head"....) I prefer the single-thread approach until high-callback-rate-per-domain-era comes, but I don't know how long when it comes. Peter? Thanks, Lai