* [PATCH v4] xen: add steal_clock support on x86
@ 2016-05-20 7:26 Juergen Gross
2016-05-20 12:02 ` Stefano Stabellini
2016-06-21 14:51 ` [Xen-devel] " David Vrabel
0 siblings, 2 replies; 3+ messages in thread
From: Juergen Gross @ 2016-05-20 7:26 UTC (permalink / raw)
To: xen-devel, linux-kernel
Cc: sstabellini, boris.ostrovsky, david.vrabel, peterz, Juergen Gross
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 <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
V4: minor adjustments as requested by Stefano Stabellini (remove
no longer needed #include, remove __init from header)
V3: add #include <asm/paravirt.h> 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 <xen/page.h>
#include <xen/interface/sched.h>
#include <xen/xen-ops.h>
-#include <asm/paravirt.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>
#include <asm/system_misc.h>
@@ -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 <linux/interrupt.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
-#include <linux/kernel_stat.h>
-#include <linux/math64.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/pvclock_gtod.h>
@@ -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 <linux/math64.h>
#include <linux/gfp.h>
+#include <asm/paravirt.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>
@@ -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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v4] xen: add steal_clock support on x86
2016-05-20 7:26 [PATCH v4] xen: add steal_clock support on x86 Juergen Gross
@ 2016-05-20 12:02 ` Stefano Stabellini
2016-06-21 14:51 ` [Xen-devel] " David Vrabel
1 sibling, 0 replies; 3+ messages in thread
From: Stefano Stabellini @ 2016-05-20 12:02 UTC (permalink / raw)
To: Juergen Gross
Cc: xen-devel, linux-kernel, sstabellini, boris.ostrovsky,
david.vrabel, peterz
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 <jgross@suse.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
> V4: minor adjustments as requested by Stefano Stabellini (remove
> no longer needed #include, remove __init from header)
> V3: add #include <asm/paravirt.h> 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 <xen/page.h>
> #include <xen/interface/sched.h>
> #include <xen/xen-ops.h>
> -#include <asm/paravirt.h>
> #include <asm/xen/hypervisor.h>
> #include <asm/xen/hypercall.h>
> #include <asm/system_misc.h>
> @@ -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 <linux/interrupt.h>
> #include <linux/clocksource.h>
> #include <linux/clockchips.h>
> -#include <linux/kernel_stat.h>
> -#include <linux/math64.h>
> #include <linux/gfp.h>
> #include <linux/slab.h>
> #include <linux/pvclock_gtod.h>
> @@ -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 <linux/math64.h>
> #include <linux/gfp.h>
>
> +#include <asm/paravirt.h>
> #include <asm/xen/hypervisor.h>
> #include <asm/xen/hypercall.h>
>
> @@ -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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Xen-devel] [PATCH v4] xen: add steal_clock support on x86
2016-05-20 7:26 [PATCH v4] xen: add steal_clock support on x86 Juergen Gross
2016-05-20 12:02 ` Stefano Stabellini
@ 2016-06-21 14:51 ` David Vrabel
1 sibling, 0 replies; 3+ messages in thread
From: David Vrabel @ 2016-06-21 14:51 UTC (permalink / raw)
To: Juergen Gross, xen-devel, linux-kernel
Cc: peterz, boris.ostrovsky, sstabellini, david.vrabel
On 20/05/16 08:26, 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.
Applied for-linus-4.8, thanks.
David
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-06-21 14:51 ` [Xen-devel] " David Vrabel
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