Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758167AbZFWM6j (ORCPT ); Tue, 23 Jun 2009 08:58:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757415AbZFWM6a (ORCPT ); Tue, 23 Jun 2009 08:58:30 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:44667 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757117AbZFWM6a (ORCPT ); Tue, 23 Jun 2009 08:58:30 -0400 Date: Tue, 23 Jun 2009 05:58:32 -0700 From: "Paul E. McKenney" To: Ingo Molnar Cc: David Howells , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, niv@us.ibm.com, dvhltc@us.ibm.com, lethal@linux-sh.org, kernel@wantstofly.org, matthew@wil.cx Subject: Re: [PATCH] v5 RCU: the bloatwatch edition Message-ID: <20090623125832.GA6872@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20090623042442.GA15630@linux.vnet.ibm.com> <28711.1245748358@redhat.com> <20090623093208.GD23698@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090623093208.GD23698@elte.hu> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3361 Lines: 89 On Tue, Jun 23, 2009 at 11:32:08AM +0200, Ingo Molnar wrote: > > * David Howells wrote: > > > Paul E. McKenney wrote: > > > > > This patch is a version of RCU designed for (!SMP && EMBEDDED) > > > provided as a proof of concept of a small-footprint RCU implementation. > > > In particular, the implementation of synchronize_rcu() is extremely > > > lightweight and high performance. It passes rcutorture testing in each > > > of the four relevant configurations (combinations of NO_HZ and PREEMPT) > > > on x86. This saves 1263 bytes compared to Classic RCU, and more than > > > three kilobytes compared to Hierarchical RCU (updated to 2.6.30): > > > > On FRV: > > > > CONFIG_CLASSIC_RCU=y > > > > text data bss dec hex filename > > 884 32 20 936 3a8 kernel/rcupdate.o > > 2616 184 0 2800 af0 kernel/rcuclassic.o > > > > CONFIG_TREE_RCU=y > > > > text data bss dec hex filename > > 884 32 20 936 3a8 kernel/rcupdate.o > > 4068 384 0 4452 1164 kernel/rcutree.o > > > > CONFIG_TINY_RCU=y > > > > text data bss dec hex filename > > 836 32 20 888 378 kernel/rcupdate.o > > 816 24 0 840 348 kernel/rcutiny.o > > > > On MN10300: > > > > CONFIG_CLASSIC_RCU=y > > > > text data bss dec hex filename > > 900 28 48 976 3d0 kernel/rcupdate.o > > 1777 184 0 1961 7a9 kernel/rcuclassic.o > > > > CONFIG_TREE_RCU=y > > > > text data bss dec hex filename > > 900 28 48 976 3d0 kernel/rcupdate.o > > 2733 384 0 3117 c2d kernel/rcutree.o > > > > CONFIG_PREEMPT_RCU=y > > > > text data bss dec hex filename > > 961 28 48 1037 40d kernel/rcupdate.o > > 3314 128 8 3450 d7a kernel/rcupreempt.o > > > > CONFIG_TINY_RCU=y > > > > text data bss dec hex filename > > 865 28 48 941 3ad kernel/rcupdate.o > > 500 24 0 524 20c kernel/rcutiny.o > > > > > Signed-off-by: Paul E. McKenney > > > > Acked-by: David Howells > Ok, that's more convincing than 900 bytes on x86. It used to be 900 bytes. In 2.6.30, it is 1263 bytes. ;-) That said, I agree that FRV and MN10300 savings are more impressive. > Paul, i guess this is .32 material anyway, right? I am personally OK with it being .32, as long as David Howells, Lennert Buytenhek, and Paul Mundt are OK with that schedule. > Since there's plenty of time, could we perhaps also do the > classic-rcu removal and integrate-rcupreempt-into-tree-rcu steps, to > reduce the (significant) config complexity perhaps? Classic-RCU removal most certainly. I am hoping to get the integrate-rcupreempt-into-tree-rcu piece done in .32 timeframe, but there is a chance that it may be a bit later. Thanx, Paul -- 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/