From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755926AbcETMC2 (ORCPT ); Fri, 20 May 2016 08:02:28 -0400 Received: from mail.kernel.org ([198.145.29.136]:60794 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754962AbcETMC1 (ORCPT ); Fri, 20 May 2016 08:02:27 -0400 Date: Fri, 20 May 2016 13:02:18 +0100 (BST) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-X260 To: Juergen Gross cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, sstabellini@kernel.org, boris.ostrovsky@oracle.com, david.vrabel@citrix.com, peterz@infradead.org Subject: Re: [PATCH v4] xen: add steal_clock support on x86 In-Reply-To: <1463729208-4238-1-git-send-email-jgross@suse.com> Message-ID: References: <1463729208-4238-1-git-send-email-jgross@suse.com> User-Agent: Alpine 2.10 (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 Fri, 20 May 2016, Juergen Gross wrote: > The pv_time_ops structure contains a function pointer for the > "steal_clock" functionality used only by KVM and Xen on ARM. Xen on x86 > uses its own mechanism to account for the "stolen" time a thread wasn't > able to run due to hypervisor scheduling. > > Add support in Xen arch independent time handling for this feature by > moving it out of the arm arch into drivers/xen and remove the x86 Xen > hack. > > Signed-off-by: Juergen Gross > Reviewed-by: Boris Ostrovsky Reviewed-by: Stefano Stabellini > V4: minor adjustments as requested by Stefano Stabellini (remove > no longer needed #include, remove __init from header) > V3: add #include to avoid build error on arm > V2: remove the x86 do_stolen_accounting() hack > --- > arch/arm/xen/enlighten.c | 18 ++---------------- > arch/x86/xen/time.c | 44 ++------------------------------------------ > drivers/xen/time.c | 20 ++++++++++++++++++++ > include/linux/kernel_stat.h | 1 - > include/xen/xen-ops.h | 1 + > kernel/sched/cputime.c | 10 ---------- > 6 files changed, 25 insertions(+), 69 deletions(-) > > diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c > index 75cd734..71db30c 100644 > --- a/arch/arm/xen/enlighten.c > +++ b/arch/arm/xen/enlighten.c > @@ -12,7 +12,6 @@ > #include > #include > #include > -#include > #include > #include > #include > @@ -84,19 +83,6 @@ int xen_unmap_domain_gfn_range(struct vm_area_struct *vma, > } > EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range); > > -static unsigned long long xen_stolen_accounting(int cpu) > -{ > - struct vcpu_runstate_info state; > - > - BUG_ON(cpu != smp_processor_id()); > - > - xen_get_runstate_snapshot(&state); > - > - WARN_ON(state.state != RUNSTATE_running); > - > - return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline]; > -} > - > static void xen_read_wallclock(struct timespec64 *ts) > { > u32 version; > @@ -355,8 +341,8 @@ static int __init xen_guest_init(void) > > register_cpu_notifier(&xen_cpu_notifier); > > - pv_time_ops.steal_clock = xen_stolen_accounting; > - static_key_slow_inc(¶virt_steal_enabled); > + xen_time_setup_guest(); > + > if (xen_initial_domain()) > pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier); > > diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c > index a0a4e55..6be31df 100644 > --- a/arch/x86/xen/time.c > +++ b/arch/x86/xen/time.c > @@ -11,8 +11,6 @@ > #include > #include > #include > -#include > -#include > #include > #include > #include > @@ -31,44 +29,6 @@ > > /* Xen may fire a timer up to this many ns early */ > #define TIMER_SLOP 100000 > -#define NS_PER_TICK (1000000000LL / HZ) > - > -/* snapshots of runstate info */ > -static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate_snapshot); > - > -/* unused ns of stolen time */ > -static DEFINE_PER_CPU(u64, xen_residual_stolen); > - > -static void do_stolen_accounting(void) > -{ > - struct vcpu_runstate_info state; > - struct vcpu_runstate_info *snap; > - s64 runnable, offline, stolen; > - cputime_t ticks; > - > - xen_get_runstate_snapshot(&state); > - > - WARN_ON(state.state != RUNSTATE_running); > - > - snap = this_cpu_ptr(&xen_runstate_snapshot); > - > - /* work out how much time the VCPU has not been runn*ing* */ > - runnable = state.time[RUNSTATE_runnable] - snap->time[RUNSTATE_runnable]; > - offline = state.time[RUNSTATE_offline] - snap->time[RUNSTATE_offline]; > - > - *snap = state; > - > - /* Add the appropriate number of ticks of stolen time, > - including any left-overs from last time. */ > - stolen = runnable + offline + __this_cpu_read(xen_residual_stolen); > - > - if (stolen < 0) > - stolen = 0; > - > - ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen); > - __this_cpu_write(xen_residual_stolen, stolen); > - account_steal_ticks(ticks); > -} > > /* Get the TSC speed from Xen */ > static unsigned long xen_tsc_khz(void) > @@ -335,8 +295,6 @@ static irqreturn_t xen_timer_interrupt(int irq, void *dev_id) > ret = IRQ_HANDLED; > } > > - do_stolen_accounting(); > - > return ret; > } > > @@ -431,6 +389,8 @@ static void __init xen_time_init(void) > xen_setup_timer(cpu); > xen_setup_cpu_clockevents(); > > + xen_time_setup_guest(); > + > if (xen_initial_domain()) > pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier); > } > diff --git a/drivers/xen/time.c b/drivers/xen/time.c > index 7107842..2257b66 100644 > --- a/drivers/xen/time.c > +++ b/drivers/xen/time.c > @@ -6,6 +6,7 @@ > #include > #include > > +#include > #include > #include > > @@ -75,6 +76,15 @@ bool xen_vcpu_stolen(int vcpu) > return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable; > } > > +static u64 xen_steal_clock(int cpu) > +{ > + struct vcpu_runstate_info state; > + > + BUG_ON(cpu != smp_processor_id()); > + xen_get_runstate_snapshot(&state); > + return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline]; > +} > + > void xen_setup_runstate_info(int cpu) > { > struct vcpu_register_runstate_memory_area area; > @@ -86,3 +96,13 @@ void xen_setup_runstate_info(int cpu) > BUG(); > } > > +void __init xen_time_setup_guest(void) > +{ > + pv_time_ops.steal_clock = xen_steal_clock; > + > + static_key_slow_inc(¶virt_steal_enabled); > + /* > + * We can't set paravirt_steal_rq_enabled as this would require the > + * capability to read another cpu's runstate info. > + */ > +} > diff --git a/include/linux/kernel_stat.h b/include/linux/kernel_stat.h > index 25a822f..44fda64 100644 > --- a/include/linux/kernel_stat.h > +++ b/include/linux/kernel_stat.h > @@ -92,7 +92,6 @@ static inline void account_process_tick(struct task_struct *tsk, int user) > extern void account_process_tick(struct task_struct *, int user); > #endif > > -extern void account_steal_ticks(unsigned long ticks); > extern void account_idle_ticks(unsigned long ticks); > > #endif /* _LINUX_KERNEL_STAT_H */ > diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h > index 86abe07..77bf9d1 100644 > --- a/include/xen/xen-ops.h > +++ b/include/xen/xen-ops.h > @@ -21,6 +21,7 @@ void xen_resume_notifier_unregister(struct notifier_block *nb); > > bool xen_vcpu_stolen(int vcpu); > void xen_setup_runstate_info(int cpu); > +void xen_time_setup_guest(void); > void xen_get_runstate_snapshot(struct vcpu_runstate_info *res); > > int xen_setup_shutdown_event(void); > diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c > index 75f98c5..8c4c6dc 100644 > --- a/kernel/sched/cputime.c > +++ b/kernel/sched/cputime.c > @@ -490,16 +490,6 @@ void account_process_tick(struct task_struct *p, int user_tick) > } > > /* > - * Account multiple ticks of steal time. > - * @p: the process from which the cpu time has been stolen > - * @ticks: number of stolen ticks > - */ > -void account_steal_ticks(unsigned long ticks) > -{ > - account_steal_time(jiffies_to_cputime(ticks)); > -} > - > -/* > * Account multiple ticks of idle time. > * @ticks: number of stolen ticks > */ > -- > 2.6.6 >