From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758444Ab3EHQHM (ORCPT ); Wed, 8 May 2013 12:07:12 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:51270 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758279Ab3EHQHJ (ORCPT ); Wed, 8 May 2013 12:07:09 -0400 X-IronPort-AV: E=Sophos;i="4.87,635,1363132800"; d="scan'208";a="22916354" Date: Wed, 8 May 2013 17:07:06 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Marc Zyngier CC: Stefano Stabellini , "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "konrad.wilk@oracle.com" , Will Deacon , "linux@arm.linux.org.uk" , "nico@linaro.org" , "cov@codeaurora.org" , "arnd@arndb.de" , "olof@lixom.net" Subject: Re: [PATCH v3 3/4] arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops In-Reply-To: <518A7763.4050509@arm.com> Message-ID: References: <1368027714-14506-3-git-send-email-stefano.stabellini@eu.citrix.com> <518A7763.4050509@arm.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 8 May 2013, Marc Zyngier wrote: > Hi Stefano, > > On 08/05/13 16:41, Stefano Stabellini wrote: > > Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM. > > > > The only paravirt interface supported is pv_time_ops.steal_clock, so no > > runtime pvops patching needed. > > > > This allows us to make use of steal_account_process_tick for stolen > > ticks accounting. > > > > Changes in v3: > > - improve commit description and Kconfig help text; > > - no need to initialize pv_time_ops; > > - add PARAVIRT_TIME_ACCOUNTING. > > > > Signed-off-by: Stefano Stabellini > > CC: linux@arm.linux.org.uk > > CC: will.deacon@arm.com > > CC: nico@linaro.org > > CC: marc.zyngier@arm.com > > CC: cov@codeaurora.org > > CC: arnd@arndb.de > > CC: olof@lixom.net > > --- > > arch/arm/Kconfig | 20 ++++++++++++++++++++ > > arch/arm/include/asm/paravirt.h | 19 +++++++++++++++++++ > > arch/arm/kernel/Makefile | 1 + > > arch/arm/kernel/paravirt.c | 25 +++++++++++++++++++++++++ > > 4 files changed, 65 insertions(+), 0 deletions(-) > > create mode 100644 arch/arm/include/asm/paravirt.h > > create mode 100644 arch/arm/kernel/paravirt.c > > > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > > index 344e299..89ee2f1 100644 > > --- a/arch/arm/Kconfig > > +++ b/arch/arm/Kconfig > > @@ -1887,12 +1887,32 @@ config XEN_DOM0 > > def_bool y > > depends on XEN > > > > +config PARAVIRT > > + bool "Enable paravirtualization code" > > + ---help--- > > + This changes the kernel so it can modify itself when it is run > > + under a hypervisor, potentially improving performance significantly > > + over full virtualization. > > + > > +config PARAVIRT_TIME_ACCOUNTING > > + bool "Paravirtual steal time accounting" > > + select PARAVIRT > > Surely you meant "depends on" instead of "select" here? Otherwise I > don't really see the point of PARAVIRT... I agree with you that "depends on" seems to be the right thing here, but on x86 is actually select. The original commit is 095c0aa83e52d6c3dd7168610746703921f570af.