Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761567Ab3DCNZy (ORCPT ); Wed, 3 Apr 2013 09:25:54 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:35174 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759070Ab3DCNZx (ORCPT ); Wed, 3 Apr 2013 09:25:53 -0400 Message-ID: <515C2DF0.7000501@oracle.com> Date: Wed, 03 Apr 2013 09:26:08 -0400 From: Boris Ostrovsky User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130219 Thunderbird/17.0.3 MIME-Version: 1.0 To: hpa@zytor.com CC: Konrad Rzeszutek Wilk , xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, rostedt@goodmis.org, kraman@redhat.com, gregkh@linuxfoundation.org, bp@alien8.de, samu.kallio@aberdeencloud.com Subject: Re: [PATCH 2/2] mm/x86: Patch out arch_flush_lazy_mmu_mode() when running on bare metal References: <9a798a0e-bc39-40db-be7f-b5e6fcc382d9@email.android.com> <1364045796-10720-1-git-send-email-konrad.wilk@oracle.com> <1364045796-10720-2-git-send-email-konrad.wilk@oracle.com> In-Reply-To: <1364045796-10720-2-git-send-email-konrad.wilk@oracle.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4867 Lines: 147 On 03/23/2013 09:36 AM, Konrad Rzeszutek Wilk wrote: > From: Boris Ostrovsky > > Invoking arch_flush_lazy_mmu_mode() results in calls to > preempt_enable()/disable() which may have performance impact. > > Since lazy MMU is not used on bare metal we can patch away > arch_flush_lazy_mmu_mode() so that it is never called in such > environment. > > Signed-off-by: Boris Ostrovsky > Tested-by: Josh Boyer > Tested-by: Konrad Rzeszutek Wilk > Acked-by: Borislav Petkov > Signed-off-by: Konrad Rzeszutek Wilk Peter, what's the status of these two patches? They are not going into 3.9, right? Thanks. -boris > --- > arch/x86/include/asm/paravirt.h | 5 ++++- > arch/x86/include/asm/paravirt_types.h | 2 ++ > arch/x86/kernel/paravirt.c | 25 +++++++++++++------------ > arch/x86/lguest/boot.c | 1 + > arch/x86/xen/mmu.c | 1 + > 5 files changed, 21 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h > index 5edd174..7361e47 100644 > --- a/arch/x86/include/asm/paravirt.h > +++ b/arch/x86/include/asm/paravirt.h > @@ -703,7 +703,10 @@ static inline void arch_leave_lazy_mmu_mode(void) > PVOP_VCALL0(pv_mmu_ops.lazy_mode.leave); > } > > -void arch_flush_lazy_mmu_mode(void); > +static inline void arch_flush_lazy_mmu_mode(void) > +{ > + PVOP_VCALL0(pv_mmu_ops.lazy_mode.flush); > +} > > static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx, > phys_addr_t phys, pgprot_t flags) > diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h > index 142236e..b3b0ec1 100644 > --- a/arch/x86/include/asm/paravirt_types.h > +++ b/arch/x86/include/asm/paravirt_types.h > @@ -91,6 +91,7 @@ struct pv_lazy_ops { > /* Set deferred update mode, used for batching operations. */ > void (*enter)(void); > void (*leave)(void); > + void (*flush)(void); > }; > > struct pv_time_ops { > @@ -679,6 +680,7 @@ void paravirt_end_context_switch(struct task_struct *next); > > void paravirt_enter_lazy_mmu(void); > void paravirt_leave_lazy_mmu(void); > +void paravirt_flush_lazy_mmu(void); > > void _paravirt_nop(void); > u32 _paravirt_ident_32(u32); > diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c > index 17fff18..8bfb335 100644 > --- a/arch/x86/kernel/paravirt.c > +++ b/arch/x86/kernel/paravirt.c > @@ -263,6 +263,18 @@ void paravirt_leave_lazy_mmu(void) > leave_lazy(PARAVIRT_LAZY_MMU); > } > > +void paravirt_flush_lazy_mmu(void) > +{ > + preempt_disable(); > + > + if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { > + arch_leave_lazy_mmu_mode(); > + arch_enter_lazy_mmu_mode(); > + } > + > + preempt_enable(); > +} > + > void paravirt_start_context_switch(struct task_struct *prev) > { > BUG_ON(preemptible()); > @@ -292,18 +304,6 @@ enum paravirt_lazy_mode paravirt_get_lazy_mode(void) > return this_cpu_read(paravirt_lazy_mode); > } > > -void arch_flush_lazy_mmu_mode(void) > -{ > - preempt_disable(); > - > - if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) { > - arch_leave_lazy_mmu_mode(); > - arch_enter_lazy_mmu_mode(); > - } > - > - preempt_enable(); > -} > - > struct pv_info pv_info = { > .name = "bare hardware", > .paravirt_enabled = 0, > @@ -475,6 +475,7 @@ struct pv_mmu_ops pv_mmu_ops = { > .lazy_mode = { > .enter = paravirt_nop, > .leave = paravirt_nop, > + .flush = paravirt_nop, > }, > > .set_fixmap = native_set_fixmap, > diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c > index 1cbd89c..7114c63 100644 > --- a/arch/x86/lguest/boot.c > +++ b/arch/x86/lguest/boot.c > @@ -1334,6 +1334,7 @@ __init void lguest_init(void) > pv_mmu_ops.read_cr3 = lguest_read_cr3; > pv_mmu_ops.lazy_mode.enter = paravirt_enter_lazy_mmu; > pv_mmu_ops.lazy_mode.leave = lguest_leave_lazy_mmu_mode; > + pv_mmu_ops.lazy_mode.flush = paravirt_flush_lazy_mmu; > pv_mmu_ops.pte_update = lguest_pte_update; > pv_mmu_ops.pte_update_defer = lguest_pte_update; > > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c > index e8e3493..f4f4105 100644 > --- a/arch/x86/xen/mmu.c > +++ b/arch/x86/xen/mmu.c > @@ -2197,6 +2197,7 @@ static const struct pv_mmu_ops xen_mmu_ops __initconst = { > .lazy_mode = { > .enter = paravirt_enter_lazy_mmu, > .leave = xen_leave_lazy_mmu, > + .flush = paravirt_flush_lazy_mmu, > }, > > .set_fixmap = xen_set_fixmap, -- 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/