Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966903Ab3E2VcP (ORCPT ); Wed, 29 May 2013 17:32:15 -0400 Received: from mail-wi0-f180.google.com ([209.85.212.180]:55600 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965980Ab3E2VcE (ORCPT ); Wed, 29 May 2013 17:32:04 -0400 Date: Wed, 29 May 2013 23:32:01 +0200 From: Frederic Weisbecker To: Benjamin Herrenschmidt Cc: Li Zhong , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, paulmck@linux.vnet.ibm.com, paulus@samba.org, michael@ellerman.id.au, Anton Blanchard Subject: Re: [RFC PATCH v3 0/5] powerpc: Support context tracking for Power pSeries Message-ID: <20130529213159.GD17419@somewhere> References: <1368422493-9831-1-git-send-email-zhong@linux.vnet.ibm.com> <1368424306.19924.20.camel@pasglop> <1368432193.2618.30.camel@ThinkPad-T5421> <1368435563.19924.28.camel@pasglop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1368435563.19924.28.camel@pasglop> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1155 Lines: 29 On Mon, May 13, 2013 at 06:59:23PM +1000, Benjamin Herrenschmidt wrote: > On Mon, 2013-05-13 at 16:03 +0800, Li Zhong wrote: > > > > To my understanding, it is used to enable RCU user extended quiescent > > state, so RCU on that cpu doesn't need scheduler ticks. And together > > with some other code(already in 3.10), we are able to remove the ticks > > in some cases (e.g. only 1 task running on the cpu, with some other > > limitations). > > Ok, sounds interesting. Once you fix the little cosmetic issue, I don't > see any reason not to merge them as it's basically wiring up an existing > feature (in that regard the patches are pretty straightforward) and I > assume the overhead is only there when you enable it. Yeah when CONFIG_RCU_USER_QS=n and CONFIG_VIRT_CPU_ACCOUNTING_GEN=n this should be zero overhead. And those configs are only needed for full dynticks. Thanks. > > Cheers, > Ben. > > -- 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/