Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753254AbbKJOSH (ORCPT ); Tue, 10 Nov 2015 09:18:07 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:63560 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752323AbbKJOSF (ORCPT ); Tue, 10 Nov 2015 09:18:05 -0500 X-IronPort-AV: E=Sophos;i="5.20,270,1444694400"; d="scan'208";a="317090592" Date: Tue, 10 Nov 2015 14:12:57 +0000 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: CC: , , , , , , Ian Campbell , , , , , Christopher Covington , Ian Campbell , , Subject: Re: [PATCH v11 3/5] arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops In-Reply-To: <1446737696-9749-3-git-send-email-stefano.stabellini@eu.citrix.com> Message-ID: References: <1446737696-9749-3-git-send-email-stefano.stabellini@eu.citrix.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4949 Lines: 162 On Thu, 5 Nov 2015, 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. > > Signed-off-by: Stefano Stabellini > Acked-by: Christopher Covington > Acked-by: Ian Campbell > 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 Russell, are you OK with this patch? > > Changes in v10: > - replace "---help---" with "help" > > Changes in v7: > - ifdef CONFIG_PARAVIRT the content of paravirt.h. > > Changes in v3: > - improve commit description and Kconfig help text; > - no need to initialize pv_time_ops; > - add PARAVIRT_TIME_ACCOUNTING. > --- > arch/arm/Kconfig | 20 ++++++++++++++++++++ > arch/arm/include/asm/paravirt.h | 20 ++++++++++++++++++++ > arch/arm/kernel/Makefile | 1 + > arch/arm/kernel/paravirt.c | 25 +++++++++++++++++++++++++ > 4 files changed, 66 insertions(+) > 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 f1ed110..60be104 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -1823,6 +1823,25 @@ config SWIOTLB > config IOMMU_HELPER > def_bool SWIOTLB > > +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 > + default n > + help > + Select this option to enable fine granularity task steal time > + accounting. Time spent executing other tasks in parallel with > + the current vCPU is discounted from the vCPU power. To account for > + that, there can be a small performance impact. > + > + If in doubt, say N here. > + > config XEN_DOM0 > def_bool y > depends on XEN > @@ -1836,6 +1855,7 @@ config XEN > select ARCH_DMA_ADDR_T_64BIT > select ARM_PSCI > select SWIOTLB_XEN > + select PARAVIRT > help > Say Y if you want to run Linux in a Virtual Machine on Xen on ARM. > > diff --git a/arch/arm/include/asm/paravirt.h b/arch/arm/include/asm/paravirt.h > new file mode 100644 > index 0000000..8435ff59 > --- /dev/null > +++ b/arch/arm/include/asm/paravirt.h > @@ -0,0 +1,20 @@ > +#ifndef _ASM_ARM_PARAVIRT_H > +#define _ASM_ARM_PARAVIRT_H > + > +#ifdef CONFIG_PARAVIRT > +struct static_key; > +extern struct static_key paravirt_steal_enabled; > +extern struct static_key paravirt_steal_rq_enabled; > + > +struct pv_time_ops { > + unsigned long long (*steal_clock)(int cpu); > +}; > +extern struct pv_time_ops pv_time_ops; > + > +static inline u64 paravirt_steal_clock(int cpu) > +{ > + return pv_time_ops.steal_clock(cpu); > +} > +#endif > + > +#endif > diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile > index af9e59b..3e6e937 100644 > --- a/arch/arm/kernel/Makefile > +++ b/arch/arm/kernel/Makefile > @@ -81,6 +81,7 @@ obj-$(CONFIG_VDSO) += vdso.o > ifneq ($(CONFIG_ARCH_EBSA110),y) > obj-y += io.o > endif > +obj-$(CONFIG_PARAVIRT) += paravirt.o > > head-y := head$(MMUEXT).o > obj-$(CONFIG_DEBUG_LL) += debug.o > diff --git a/arch/arm/kernel/paravirt.c b/arch/arm/kernel/paravirt.c > new file mode 100644 > index 0000000..53f371e > --- /dev/null > +++ b/arch/arm/kernel/paravirt.c > @@ -0,0 +1,25 @@ > +/* > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + * Copyright (C) 2013 Citrix Systems > + * > + * Author: Stefano Stabellini > + */ > + > +#include > +#include > +#include > +#include > + > +struct static_key paravirt_steal_enabled; > +struct static_key paravirt_steal_rq_enabled; > + > +struct pv_time_ops pv_time_ops; > +EXPORT_SYMBOL_GPL(pv_time_ops); > -- > 1.7.10.4 > -- 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/