[PATCH v9 0/5] xen/arm/arm64: CONFIG_PARAVIRT and stolen ticks accounting

[PATCH v9 0/5] xen/arm/arm64: CONFIG_PARAVIRT and stolen ticks accounting

[Stefano Stabellini]

Hi all,
this patch series introduces stolen ticks accounting for Xen on ARM and
ARM64.
Stolen ticks are clocksource ticks that have been "stolen" from the cpu,
typically because Linux is running in a virtual machine and the vcpu has
been descheduled.
To account for these ticks we introduce CONFIG_PARAVIRT and pv_time_ops
so that we can make use of:

kernel/sched/cputime.c:steal_account_process_tick


Changes in v9:
- added back missing new files from patches;
- fix compilation on avr32 (remove patch #5, revert to previous version
  of patch #2).



Stefano Stabellini (5):
      xen: move xen_setup_runstate_info and get_runstate_snapshot to drivers/xen/time.c
      kernel: missing include in cputime.c
      arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
      arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
      xen/arm: account for stolen ticks

 arch/arm/Kconfig                  |   20 ++++++++
 arch/arm/include/asm/paravirt.h   |   20 ++++++++
 arch/arm/kernel/Makefile          |    2 +
 arch/arm/kernel/paravirt.c        |   25 ++++++++++
 arch/arm/xen/enlighten.c          |   21 +++++++++
 arch/arm64/Kconfig                |   20 ++++++++
 arch/arm64/include/asm/paravirt.h |   20 ++++++++
 arch/arm64/kernel/Makefile        |    1 +
 arch/arm64/kernel/paravirt.c      |   25 ++++++++++
 arch/ia64/xen/time.c              |   48 +++----------------
 arch/x86/xen/time.c               |   76 +------------------------------
 drivers/xen/Makefile              |    2 +-
 drivers/xen/time.c                |   91 +++++++++++++++++++++++++++++++++++++
 include/xen/xen-ops.h             |    5 ++
 kernel/sched/cputime.c            |    3 ++
 15 files changed, 261 insertions(+), 118 deletions(-)
 create mode 100644 arch/arm/include/asm/paravirt.h
 create mode 100644 arch/arm/kernel/paravirt.c
 create mode 100644 arch/arm64/include/asm/paravirt.h
 create mode 100644 arch/arm64/kernel/paravirt.c
 create mode 100644 drivers/xen/time.c


git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git lost_ticks_9


Cheers,

Stefano

[PATCH v9 1/5] xen: move xen_setup_runstate_info and get_runstate_snapshot to drivers/xen/time.c

[Stefano Stabellini]

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: konrad.wilk@oracle.com

---

Changes in v2:
- leave do_stolen_accounting in arch/x86/xen/time.c;
- use the new common functions in arch/ia64/xen/time.c.
---
 arch/ia64/xen/time.c  |   48 ++++----------------------
 arch/x86/xen/time.c   |   76 +----------------------------------------
 drivers/xen/Makefile  |    2 +-
 drivers/xen/time.c    |   91 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/xen/xen-ops.h |    5 +++
 5 files changed, 104 insertions(+), 118 deletions(-)
 create mode 100644 drivers/xen/time.c

diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c
index 1f8244a..79a0b8c 100644
--- a/arch/ia64/xen/time.c
+++ b/arch/ia64/xen/time.c
@@ -34,53 +34,17 @@
 
 #include "../kernel/fsyscall_gtod_data.h"
 
-static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);
 static DEFINE_PER_CPU(unsigned long, xen_stolen_time);
 static DEFINE_PER_CPU(unsigned long, xen_blocked_time);
 
 /* taken from i386/kernel/time-xen.c */
 static void xen_init_missing_ticks_accounting(int cpu)
 {
-	struct vcpu_register_runstate_memory_area area;
-	struct vcpu_runstate_info *runstate = &per_cpu(xen_runstate, cpu);
-	int rc;
+	xen_setup_runstate_info(&runstate);
 
-	memset(runstate, 0, sizeof(*runstate));
-
-	area.addr.v = runstate;
-	rc = HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area, cpu,
-				&area);
-	WARN_ON(rc && rc != -ENOSYS);
-
-	per_cpu(xen_blocked_time, cpu) = runstate->time[RUNSTATE_blocked];
-	per_cpu(xen_stolen_time, cpu) = runstate->time[RUNSTATE_runnable]
-					    + runstate->time[RUNSTATE_offline];
-}
-
-/*
- * Runstate accounting
- */
-/* stolen from arch/x86/xen/time.c */
-static void get_runstate_snapshot(struct vcpu_runstate_info *res)
-{
-	u64 state_time;
-	struct vcpu_runstate_info *state;
-
-	BUG_ON(preemptible());
-
-	state = &__get_cpu_var(xen_runstate);
-
-	/*
-	 * The runstate info is always updated by the hypervisor on
-	 * the current CPU, so there's no need to use anything
-	 * stronger than a compiler barrier when fetching it.
-	 */
-	do {
-		state_time = state->state_entry_time;
-		rmb();
-		*res = *state;
-		rmb();
-	} while (state->state_entry_time != state_time);
+	per_cpu(xen_blocked_time, cpu) = runstate.time[RUNSTATE_blocked];
+	per_cpu(xen_stolen_time, cpu) = runstate.time[RUNSTATE_runnable]
+					    + runstate.time[RUNSTATE_offline];
 }
 
 #define NS_PER_TICK (1000000000LL/HZ)
@@ -94,7 +58,7 @@ consider_steal_time(unsigned long new_itm)
 	struct vcpu_runstate_info runstate;
 	struct task_struct *p = current;
 
-	get_runstate_snapshot(&runstate);
+	xen_get_runstate_snapshot(&runstate);
 
 	/*
 	 * Check for vcpu migration effect
@@ -202,7 +166,7 @@ static unsigned long long xen_sched_clock(void)
 	 */
 	now = ia64_native_sched_clock();
 
-	get_runstate_snapshot(&runstate);
+	xen_get_runstate_snapshot(&runstate);
 
 	WARN_ON(runstate.state != RUNSTATE_running);
 
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 12a1ca7..d479444 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -32,86 +32,12 @@
 #define TIMER_SLOP	100000
 #define NS_PER_TICK	(1000000000LL / HZ)
 
-/* runstate info updated by Xen */
-static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);
-
 /* 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);
 
-/* return an consistent snapshot of 64-bit time/counter value */
-static u64 get64(const u64 *p)
-{
-	u64 ret;
-
-	if (BITS_PER_LONG < 64) {
-		u32 *p32 = (u32 *)p;
-		u32 h, l;
-
-		/*
-		 * Read high then low, and then make sure high is
-		 * still the same; this will only loop if low wraps
-		 * and carries into high.
-		 * XXX some clean way to make this endian-proof?
-		 */
-		do {
-			h = p32[1];
-			barrier();
-			l = p32[0];
-			barrier();
-		} while (p32[1] != h);
-
-		ret = (((u64)h) << 32) | l;
-	} else
-		ret = *p;
-
-	return ret;
-}
-
-/*
- * Runstate accounting
- */
-static void get_runstate_snapshot(struct vcpu_runstate_info *res)
-{
-	u64 state_time;
-	struct vcpu_runstate_info *state;
-
-	BUG_ON(preemptible());
-
-	state = &__get_cpu_var(xen_runstate);
-
-	/*
-	 * The runstate info is always updated by the hypervisor on
-	 * the current CPU, so there's no need to use anything
-	 * stronger than a compiler barrier when fetching it.
-	 */
-	do {
-		state_time = get64(&state->state_entry_time);
-		barrier();
-		*res = *state;
-		barrier();
-	} while (get64(&state->state_entry_time) != state_time);
-}
-
-/* return true when a vcpu could run but has no real cpu to run on */
-bool xen_vcpu_stolen(int vcpu)
-{
-	return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
-}
-
-void xen_setup_runstate_info(int cpu)
-{
-	struct vcpu_register_runstate_memory_area area;
-
-	area.addr.v = &per_cpu(xen_runstate, cpu);
-
-	if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area,
-			       cpu, &area))
-		BUG();
-}
-
 static void do_stolen_accounting(void)
 {
 	struct vcpu_runstate_info state;
@@ -119,7 +45,7 @@ static void do_stolen_accounting(void)
 	s64 runnable, offline, stolen;
 	cputime_t ticks;
 
-	get_runstate_snapshot(&state);
+	xen_get_runstate_snapshot(&state);
 
 	WARN_ON(state.state != RUNSTATE_running);
 
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 14fe79d..cd95fb7 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -2,7 +2,7 @@ ifeq ($(filter y, $(CONFIG_ARM) $(CONFIG_ARM64)),)
 obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
 endif
 obj-$(CONFIG_X86)			+= fallback.o
-obj-y	+= grant-table.o features.o events.o balloon.o manage.o
+obj-y	+= grant-table.o features.o events.o balloon.o manage.o time.o
 obj-y	+= xenbus/
 
 nostackp := $(call cc-option, -fno-stack-protector)
diff --git a/drivers/xen/time.c b/drivers/xen/time.c
new file mode 100644
index 0000000..c2e39d3
--- /dev/null
+++ b/drivers/xen/time.c
@@ -0,0 +1,91 @@
+/*
+ * Xen stolen ticks accounting.
+ */
+#include <linux/kernel.h>
+#include <linux/kernel_stat.h>
+#include <linux/math64.h>
+#include <linux/gfp.h>
+
+#include <asm/xen/hypervisor.h>
+#include <asm/xen/hypercall.h>
+
+#include <xen/events.h>
+#include <xen/features.h>
+#include <xen/interface/xen.h>
+#include <xen/interface/vcpu.h>
+#include <xen/xen-ops.h>
+
+/* runstate info updated by Xen */
+static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);
+
+/* return an consistent snapshot of 64-bit time/counter value */
+static u64 get64(const u64 *p)
+{
+	u64 ret;
+
+	if (BITS_PER_LONG < 64) {
+		u32 *p32 = (u32 *)p;
+		u32 h, l;
+
+		/*
+		 * Read high then low, and then make sure high is
+		 * still the same; this will only loop if low wraps
+		 * and carries into high.
+		 * XXX some clean way to make this endian-proof?
+		 */
+		do {
+			h = p32[1];
+			barrier();
+			l = p32[0];
+			barrier();
+		} while (p32[1] != h);
+
+		ret = (((u64)h) << 32) | l;
+	} else
+		ret = *p;
+
+	return ret;
+}
+
+/*
+ * Runstate accounting
+ */
+void xen_get_runstate_snapshot(struct vcpu_runstate_info *res)
+{
+	u64 state_time;
+	struct vcpu_runstate_info *state;
+
+	BUG_ON(preemptible());
+
+	state = &__get_cpu_var(xen_runstate);
+
+	/*
+	 * The runstate info is always updated by the hypervisor on
+	 * the current CPU, so there's no need to use anything
+	 * stronger than a compiler barrier when fetching it.
+	 */
+	do {
+		state_time = get64(&state->state_entry_time);
+		barrier();
+		*res = *state;
+		barrier();
+	} while (get64(&state->state_entry_time) != state_time);
+}
+
+/* return true when a vcpu could run but has no real cpu to run on */
+bool xen_vcpu_stolen(int vcpu)
+{
+	return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
+}
+
+void xen_setup_runstate_info(int cpu)
+{
+	struct vcpu_register_runstate_memory_area area;
+
+	area.addr.v = &per_cpu(xen_runstate, cpu);
+
+	if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area,
+			       cpu, &area))
+		BUG();
+}
+
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index fb2ea8f..ee3303b 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -3,6 +3,7 @@
 
 #include <linux/percpu.h>
 #include <asm/xen/interface.h>
+#include <xen/interface/vcpu.h>
 
 DECLARE_PER_CPU(struct vcpu_info *, xen_vcpu);
 
@@ -16,6 +17,10 @@ void xen_mm_unpin_all(void);
 void xen_timer_resume(void);
 void xen_arch_resume(void);
 
+bool xen_vcpu_stolen(int vcpu);
+void xen_setup_runstate_info(int cpu);
+void xen_get_runstate_snapshot(struct vcpu_runstate_info *res);
+
 int xen_setup_shutdown_event(void);
 
 extern unsigned long *xen_contiguous_bitmap;
-- 
1.7.10.4

[PATCH v9 2/5] kernel: missing include in cputime.c

[Stefano Stabellini]

steal_account_process_tick calls paravirt_steal_clock, but paravirt.h is
currently missing amoung the included header files.
Add include asm/paravirt.h.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: mingo@redhat.com
CC: peterz@infradead.org
---
 kernel/sched/cputime.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 9994791..951833e 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -5,6 +5,9 @@
 #include <linux/static_key.h>
 #include <linux/context_tracking.h>
 #include "sched.h"
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#endif
 
 
 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
-- 
1.7.10.4

Re: [PATCH v9 2/5] kernel: missing include in cputime.c

[Stefano Stabellini]

Peter,
is this patch OK for you?

On Thu, 9 Jan 2014, Stefano Stabellini wrote:
> steal_account_process_tick calls paravirt_steal_clock, but paravirt.h is
> currently missing among the included header files.
> Add include asm/paravirt.h.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> CC: mingo@redhat.com
> CC: peterz@infradead.org
> ---
>  kernel/sched/cputime.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> index 9994791..951833e 100644
> --- a/kernel/sched/cputime.c
> +++ b/kernel/sched/cputime.c
> @@ -5,6 +5,9 @@
>  #include <linux/static_key.h>
>  #include <linux/context_tracking.h>
>  #include "sched.h"
> +#ifdef CONFIG_PARAVIRT
> +#include <asm/paravirt.h>
> +#endif
>  
>  
>  #ifdef CONFIG_IRQ_TIME_ACCOUNTING
> -- 
> 1.7.10.4
> 

Re: [PATCH v9 2/5] kernel: missing include in cputime.c

[Stefano Stabellini]

Peter,
I am sorry for the confusion, I have already asked you this question and
you have already kindly given me feedback on it. I have even addressed
the problem and resent.

However I wrongly tagged my emails and patch series.
The right patch are v7 and v8, without #ifdef CONFIG_PARAVIRT in
cputime.c:

http://marc.info/?l=linux-kernel&m=138920709703581&w=2

also appended below. I am very sorry for the confusion.
Would that be OK for you?

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index 9994791..9f9b76a 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -5,6 +5,7 @@
 #include <linux/static_key.h>
 #include <linux/context_tracking.h>
 #include "sched.h"
+#include <asm/paravirt.h>
 
 
 #ifdef CONFIG_IRQ_TIME_ACCOUNTING

On Tue, 25 Mar 2014, Stefano Stabellini wrote:
> Peter,
> is this patch OK for you?
> 
> On Thu, 9 Jan 2014, Stefano Stabellini wrote:
> > steal_account_process_tick calls paravirt_steal_clock, but paravirt.h is
> > currently missing among the included header files.
> > Add include asm/paravirt.h.
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> > CC: mingo@redhat.com
> > CC: peterz@infradead.org
> > ---
> >  kernel/sched/cputime.c |    3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
> > index 9994791..951833e 100644
> > --- a/kernel/sched/cputime.c
> > +++ b/kernel/sched/cputime.c
> > @@ -5,6 +5,9 @@
> >  #include <linux/static_key.h>
> >  #include <linux/context_tracking.h>
> >  #include "sched.h"
> > +#ifdef CONFIG_PARAVIRT
> > +#include <asm/paravirt.h>
> > +#endif
> >  
> >  
> >  #ifdef CONFIG_IRQ_TIME_ACCOUNTING
> > -- 
> > 1.7.10.4
> > 
> 

[PATCH v9 3/5] arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

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 <stefano.stabellini@eu.citrix.com>
Acked-by: Christopher Covington <cov@codeaurora.org>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
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

---

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        |    2 ++
 arch/arm/kernel/paravirt.c      |   25 +++++++++++++++++++++++++
 4 files changed, 67 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 c1f1a7e..d6c3ba1 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1874,6 +1874,25 @@ 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
@@ -1885,6 +1904,7 @@ config XEN
 	depends on !GENERIC_ATOMIC64
 	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 a30fc9b..34cf9a6 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -87,6 +87,7 @@ obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
 ifneq ($(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
@@ -97,5 +98,6 @@ ifeq ($(CONFIG_ARM_PSCI),y)
 obj-y				+= psci.o
 obj-$(CONFIG_SMP)		+= psci_smp.o
 endif
+obj-$(CONFIG_PARAVIRT)	+= paravirt.o
 
 extra-y := $(head-y) vmlinux.lds
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 <stefano.stabellini@eu.citrix.com>
+ */
+
+#include <linux/export.h>
+#include <linux/jump_label.h>
+#include <linux/types.h>
+#include <asm/paravirt.h>
+
+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

Re: [PATCH v9 3/5] arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

On Thu, 9 Jan 2014, 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 <stefano.stabellini@eu.citrix.com>
> Acked-by: Christopher Covington <cov@codeaurora.org>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
> 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? Do you have an opinion on this?


> 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        |    2 ++
>  arch/arm/kernel/paravirt.c      |   25 +++++++++++++++++++++++++
>  4 files changed, 67 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 c1f1a7e..d6c3ba1 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1874,6 +1874,25 @@ 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
> @@ -1885,6 +1904,7 @@ config XEN
>  	depends on !GENERIC_ATOMIC64
>  	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 a30fc9b..34cf9a6 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -87,6 +87,7 @@ obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
>  ifneq ($(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 <stefano.stabellini@eu.citrix.com>
> + */
> +
> +#include <linux/export.h>
> +#include <linux/jump_label.h>
> +#include <linux/types.h>
> +#include <asm/paravirt.h>
> +
> +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
> 

Re: [PATCH v9 3/5] arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

On Thu, 9 Jan 2014, 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 <stefano.stabellini@eu.citrix.com>
> Acked-by: Christopher Covington <cov@codeaurora.org>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
> 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 happy with this patch (for 3.15)?



> 
> 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        |    2 ++
>  arch/arm/kernel/paravirt.c      |   25 +++++++++++++++++++++++++
>  4 files changed, 67 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 c1f1a7e..d6c3ba1 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1874,6 +1874,25 @@ 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
> @@ -1885,6 +1904,7 @@ config XEN
>  	depends on !GENERIC_ATOMIC64
>  	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 a30fc9b..34cf9a6 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -87,6 +87,7 @@ obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
>  ifneq ($(CONFIG_ARCH_EBSA110),y)
>    obj-y		+= io.o
>  endif
> +obj-$(CONFIG_PARAVIRT)	+= paravirt.o
>  
>  head-y			:= head$(MMUEXT).o
>  obj-$(CONFIG_DEBUG_LL)	+= debug.o
> @@ -97,5 +98,6 @@ ifeq ($(CONFIG_ARM_PSCI),y)
>  obj-y				+= psci.o
>  obj-$(CONFIG_SMP)		+= psci_smp.o
>  endif
> +obj-$(CONFIG_PARAVIRT)	+= paravirt.o
>  
>  extra-y := $(head-y) vmlinux.lds
> 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 <stefano.stabellini@eu.citrix.com>
> + */
> +
> +#include <linux/export.h>
> +#include <linux/jump_label.h>
> +#include <linux/types.h>
> +#include <asm/paravirt.h>
> +
> +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
> 

Re: [PATCH v9 3/5] arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

On Thu, 9 Jan 2014, 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 <stefano.stabellini@eu.citrix.com>
> Acked-by: Christopher Covington <cov@codeaurora.org>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
> 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,
it this patch OK for you?

 
> 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        |    2 ++
>  arch/arm/kernel/paravirt.c      |   25 +++++++++++++++++++++++++
>  4 files changed, 67 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 c1f1a7e..d6c3ba1 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1874,6 +1874,25 @@ 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
> @@ -1885,6 +1904,7 @@ config XEN
>  	depends on !GENERIC_ATOMIC64
>  	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 a30fc9b..34cf9a6 100644
> --- a/arch/arm/kernel/Makefile
> +++ b/arch/arm/kernel/Makefile
> @@ -87,6 +87,7 @@ obj-$(CONFIG_ARM_CPU_TOPOLOGY)  += topology.o
>  ifneq ($(CONFIG_ARCH_EBSA110),y)
>    obj-y		+= io.o
>  endif
> +obj-$(CONFIG_PARAVIRT)	+= paravirt.o
>  
>  head-y			:= head$(MMUEXT).o
>  obj-$(CONFIG_DEBUG_LL)	+= debug.o
> @@ -97,5 +98,6 @@ ifeq ($(CONFIG_ARM_PSCI),y)
>  obj-y				+= psci.o
>  obj-$(CONFIG_SMP)		+= psci_smp.o
>  endif
> +obj-$(CONFIG_PARAVIRT)	+= paravirt.o
>  
>  extra-y := $(head-y) vmlinux.lds
> 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 <stefano.stabellini@eu.citrix.com>
> + */
> +
> +#include <linux/export.h>
> +#include <linux/jump_label.h>
> +#include <linux/types.h>
> +#include <asm/paravirt.h>
> +
> +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
> 

[PATCH v9 4/5] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
Necessary duplication of paravirt.h and paravirt.c with 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 <stefano.stabellini@eu.citrix.com>
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
CC: Catalin.Marinas@arm.com

---

Changes in v7:
- ifdef CONFIG_PARAVIRT the content of paravirt.h.
---
 arch/arm64/Kconfig                |   20 ++++++++++++++++++++
 arch/arm64/include/asm/paravirt.h |   20 ++++++++++++++++++++
 arch/arm64/kernel/Makefile        |    1 +
 arch/arm64/kernel/paravirt.c      |   25 +++++++++++++++++++++++++
 4 files changed, 66 insertions(+)
 create mode 100644 arch/arm64/include/asm/paravirt.h
 create mode 100644 arch/arm64/kernel/paravirt.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 6d4dd22..d1003ba 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -212,6 +212,25 @@ config HAVE_ARCH_TRANSPARENT_HUGEPAGE
 
 source "mm/Kconfig"
 
+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
@@ -220,6 +239,7 @@ config XEN
 	bool "Xen guest support on ARM64 (EXPERIMENTAL)"
 	depends on ARM64 && OF
 	select SWIOTLB_XEN
+	select PARAVIRT
 	help
 	  Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.
 
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
new file mode 100644
index 0000000..fd5f428
--- /dev/null
+++ b/arch/arm64/include/asm/paravirt.h
@@ -0,0 +1,20 @@
+#ifndef _ASM_ARM64_PARAVIRT_H
+#define _ASM_ARM64_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/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 5ba2fd4..1dee735 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -18,6 +18,7 @@ arm64-obj-$(CONFIG_SMP)			+= smp.o smp_spin_table.o
 arm64-obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o
 arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o
 arm64-obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
+arm64-obj-$(CONFIG_PARAVIRT)		+= paravirt.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
new file mode 100644
index 0000000..53f371e
--- /dev/null
+++ b/arch/arm64/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 <stefano.stabellini@eu.citrix.com>
+ */
+
+#include <linux/export.h>
+#include <linux/jump_label.h>
+#include <linux/types.h>
+#include <asm/paravirt.h>
+
+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

Re: [PATCH v9 4/5] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Catalin Marinas]

On Thu, Jan 09, 2014 at 06:32:15PM +0000, Stefano Stabellini wrote:
> Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
> Necessary duplication of paravirt.h and paravirt.c with 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 <stefano.stabellini@eu.citrix.com>
> 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
> CC: Catalin.Marinas@arm.com

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v9 4/5] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

On Thu, 9 Jan 2014, Stefano Stabellini wrote:
> Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
> Necessary duplication of paravirt.h and paravirt.c with 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 <stefano.stabellini@eu.citrix.com>
> 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
> CC: Catalin.Marinas@arm.com

Catalin, Will, are you happy with this patch for 3.15?

 
> Changes in v7:
> - ifdef CONFIG_PARAVIRT the content of paravirt.h.
> ---
>  arch/arm64/Kconfig                |   20 ++++++++++++++++++++
>  arch/arm64/include/asm/paravirt.h |   20 ++++++++++++++++++++
>  arch/arm64/kernel/Makefile        |    1 +
>  arch/arm64/kernel/paravirt.c      |   25 +++++++++++++++++++++++++
>  4 files changed, 66 insertions(+)
>  create mode 100644 arch/arm64/include/asm/paravirt.h
>  create mode 100644 arch/arm64/kernel/paravirt.c
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 6d4dd22..d1003ba 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -212,6 +212,25 @@ config HAVE_ARCH_TRANSPARENT_HUGEPAGE
>  
>  source "mm/Kconfig"
>  
> +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
> @@ -220,6 +239,7 @@ config XEN
>  	bool "Xen guest support on ARM64 (EXPERIMENTAL)"
>  	depends on ARM64 && OF
>  	select SWIOTLB_XEN
> +	select PARAVIRT
>  	help
>  	  Say Y if you want to run Linux in a Virtual Machine on Xen on ARM64.
>  
> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
> new file mode 100644
> index 0000000..fd5f428
> --- /dev/null
> +++ b/arch/arm64/include/asm/paravirt.h
> @@ -0,0 +1,20 @@
> +#ifndef _ASM_ARM64_PARAVIRT_H
> +#define _ASM_ARM64_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/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 5ba2fd4..1dee735 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -18,6 +18,7 @@ arm64-obj-$(CONFIG_SMP)			+= smp.o smp_spin_table.o
>  arm64-obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event.o
>  arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT)+= hw_breakpoint.o
>  arm64-obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
> +arm64-obj-$(CONFIG_PARAVIRT)		+= paravirt.o
>  
>  obj-y					+= $(arm64-obj-y) vdso/
>  obj-m					+= $(arm64-obj-m)
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> new file mode 100644
> index 0000000..53f371e
> --- /dev/null
> +++ b/arch/arm64/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 <stefano.stabellini@eu.citrix.com>
> + */
> +
> +#include <linux/export.h>
> +#include <linux/jump_label.h>
> +#include <linux/types.h>
> +#include <asm/paravirt.h>
> +
> +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
> 

Re: [PATCH v9 4/5] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Catalin Marinas]

On Mon, Feb 17, 2014 at 12:25:42PM +0000, Stefano Stabellini wrote:
> On Thu, 9 Jan 2014, Stefano Stabellini wrote:
> > Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
> > Necessary duplication of paravirt.h and paravirt.c with 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 <stefano.stabellini@eu.citrix.com>
> > 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
> > CC: Catalin.Marinas@arm.com
> 
> Catalin, Will, are you happy with this patch for 3.15?

It's pretty small and looks fine to me. However, I would like someone
with more virtualisation experience than me to ack it (e.g. Marc Z).

Some nitpicks:

> > +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---

For consistency with this file, just use "help" rather than
"---help---".

> > --- /dev/null
> > +++ b/arch/arm64/include/asm/paravirt.h
> > @@ -0,0 +1,20 @@
> > +#ifndef _ASM_ARM64_PARAVIRT_H
> > +#define _ASM_ARM64_PARAVIRT_H

__ASM_PARAVIRT_H for consistency.

-- 
Catalin

Re: [PATCH v9 4/5] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

On Mon, 17 Feb 2014, Catalin Marinas wrote:
> On Mon, Feb 17, 2014 at 12:25:42PM +0000, Stefano Stabellini wrote:
> > On Thu, 9 Jan 2014, Stefano Stabellini wrote:
> > > Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
> > > Necessary duplication of paravirt.h and paravirt.c with 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 <stefano.stabellini@eu.citrix.com>
> > > 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
> > > CC: Catalin.Marinas@arm.com
> > 
> > Catalin, Will, are you happy with this patch for 3.15?
> 
> It's pretty small and looks fine to me. However, I would like someone
> with more virtualisation experience than me to ack it (e.g. Marc Z).

Ping? Marc, could you please give it a review?


> Some nitpicks:
> 
> > > +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---
> 
> For consistency with this file, just use "help" rather than
> "---help---".
> 
> > > --- /dev/null
> > > +++ b/arch/arm64/include/asm/paravirt.h
> > > @@ -0,0 +1,20 @@
> > > +#ifndef _ASM_ARM64_PARAVIRT_H
> > > +#define _ASM_ARM64_PARAVIRT_H
> 
> __ASM_PARAVIRT_H for consistency.
> 
> -- 
> Catalin
> 

Re: [PATCH v9 4/5] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Marc Zyngier]

On 25/03/14 11:19, Stefano Stabellini wrote:
> On Mon, 17 Feb 2014, Catalin Marinas wrote:
>> On Mon, Feb 17, 2014 at 12:25:42PM +0000, Stefano Stabellini wrote:
>>> On Thu, 9 Jan 2014, Stefano Stabellini wrote:
>>>> Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
>>>> Necessary duplication of paravirt.h and paravirt.c with 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 <stefano.stabellini@eu.citrix.com>
>>>> 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
>>>> CC: Catalin.Marinas@arm.com
>>>
>>> Catalin, Will, are you happy with this patch for 3.15?
>>
>> It's pretty small and looks fine to me. However, I would like someone
>> with more virtualisation experience than me to ack it (e.g. Marc Z).
> 
> Ping? Marc, could you please give it a review?

Yup, that looks OK to me. It's a generic feature anyway, so I don't see
any harm in enabling it for Xen. We may also use it for KVM at some point.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH v9 4/5] arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops

[Stefano Stabellini]

On Tue, 25 Mar 2014, Marc Zyngier wrote:
> On 25/03/14 11:19, Stefano Stabellini wrote:
> > On Mon, 17 Feb 2014, Catalin Marinas wrote:
> >> On Mon, Feb 17, 2014 at 12:25:42PM +0000, Stefano Stabellini wrote:
> >>> On Thu, 9 Jan 2014, Stefano Stabellini wrote:
> >>>> Introduce CONFIG_PARAVIRT and PARAVIRT_TIME_ACCOUNTING on ARM64.
> >>>> Necessary duplication of paravirt.h and paravirt.c with 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 <stefano.stabellini@eu.citrix.com>
> >>>> 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
> >>>> CC: Catalin.Marinas@arm.com
> >>>
> >>> Catalin, Will, are you happy with this patch for 3.15?
> >>
> >> It's pretty small and looks fine to me. However, I would like someone
> >> with more virtualisation experience than me to ack it (e.g. Marc Z).
> > 
> > Ping? Marc, could you please give it a review?
> 
> Yup, that looks OK to me. It's a generic feature anyway, so I don't see
> any harm in enabling it for Xen. We may also use it for KVM at some point.
> 
> Acked-by: Marc Zyngier <marc.zyngier@arm.com>

Thanks!

[PATCH v9 5/5] xen/arm: account for stolen ticks

[Stefano Stabellini]

Register the runstate_memory_area with the hypervisor.
Use pv_time_ops.steal_clock to account for stolen ticks.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>


---

Changes in v4:
- don't use paravirt_steal_rq_enabled: we do not support retrieving
stolen ticks for vcpus other than one we are running on.

Changes in v3:
- use BUG_ON and smp_processor_id.
---
 arch/arm/xen/enlighten.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index 8550123..fa8bdc0 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -14,7 +14,10 @@
 #include <xen/xen-ops.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
+#include <asm/arch_timer.h>
 #include <asm/system_misc.h>
+#include <asm/paravirt.h>
+#include <linux/jump_label.h>
 #include <linux/interrupt.h>
 #include <linux/irqreturn.h>
 #include <linux/module.h>
@@ -154,6 +157,19 @@ int xen_unmap_domain_mfn_range(struct vm_area_struct *vma,
 }
 EXPORT_SYMBOL_GPL(xen_unmap_domain_mfn_range);
 
+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 __init xen_percpu_init(void *unused)
 {
 	struct vcpu_register_vcpu_info info;
@@ -171,6 +187,8 @@ static void __init xen_percpu_init(void *unused)
 	BUG_ON(err);
 	per_cpu(xen_vcpu, cpu) = vcpup;
 
+	xen_setup_runstate_info(cpu);
+
 	enable_percpu_irq(xen_events_irq, 0);
 	put_cpu();
 }
@@ -313,6 +331,9 @@ static int __init xen_init_events(void)
 
 	on_each_cpu(xen_percpu_init, NULL, 0);
 
+	pv_time_ops.steal_clock = xen_stolen_accounting;
+	static_key_slow_inc(&paravirt_steal_enabled);
+
 	return 0;
 }
 postcore_initcall(xen_init_events);
-- 
1.7.10.4

Re: [Xen-devel] [PATCH v9 0/5] xen/arm/arm64: CONFIG_PARAVIRT and stolen ticks accounting

[Konrad Rzeszutek Wilk]

On Thu, Jan 09, 2014 at 06:15:07PM +0000, Stefano Stabellini wrote:
> Hi all,
> this patch series introduces stolen ticks accounting for Xen on ARM and
> ARM64.
> Stolen ticks are clocksource ticks that have been "stolen" from the cpu,
> typically because Linux is running in a virtual machine and the vcpu has
> been descheduled.
> To account for these ticks we introduce CONFIG_PARAVIRT and pv_time_ops
> so that we can make use of:
> 
> kernel/sched/cputime.c:steal_account_process_tick
> 
> 
> Changes in v9:
> - added back missing new files from patches;
> - fix compilation on avr32 (remove patch #5, revert to previous version
>   of patch #2).
> 
> 
> 
> Stefano Stabellini (5):
>       xen: move xen_setup_runstate_info and get_runstate_snapshot to drivers/xen/time.c
>       kernel: missing include in cputime.c
>       arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
>       arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
>       xen/arm: account for stolen ticks
> 
>  arch/arm/Kconfig                  |   20 ++++++++
>  arch/arm/include/asm/paravirt.h   |   20 ++++++++
>  arch/arm/kernel/Makefile          |    2 +
>  arch/arm/kernel/paravirt.c        |   25 ++++++++++
>  arch/arm/xen/enlighten.c          |   21 +++++++++
>  arch/arm64/Kconfig                |   20 ++++++++
>  arch/arm64/include/asm/paravirt.h |   20 ++++++++
>  arch/arm64/kernel/Makefile        |    1 +
>  arch/arm64/kernel/paravirt.c      |   25 ++++++++++
>  arch/ia64/xen/time.c              |   48 +++----------------
>  arch/x86/xen/time.c               |   76 +------------------------------
>  drivers/xen/Makefile              |    2 +-
>  drivers/xen/time.c                |   91 +++++++++++++++++++++++++++++++++++++
>  include/xen/xen-ops.h             |    5 ++
>  kernel/sched/cputime.c            |    3 ++
>  15 files changed, 261 insertions(+), 118 deletions(-)
>  create mode 100644 arch/arm/include/asm/paravirt.h
>  create mode 100644 arch/arm/kernel/paravirt.c
>  create mode 100644 arch/arm64/include/asm/paravirt.h
>  create mode 100644 arch/arm64/kernel/paravirt.c
>  create mode 100644 drivers/xen/time.c
> 
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git lost_ticks_9

I tried to merge it on top of 3.14-rc1 + stable/for-linus-3.14 (which
has the revert of " xen/grant-table: Avoid m2p_override during mapping"


And I get:
konrad@phenom:~/linux$ git merge stefano/lost_ticks_9
Auto-merging drivers/xen/Makefile
CONFLICT (content): Merge conflict in drivers/xen/Makefile
Auto-merging arch/x86/xen/time.c
CONFLICT (modify/delete): arch/ia64/xen/time.c deleted in HEAD and
modified in stefano/lost_ticks_9. Version stefano/lost_ticks_9 of
arch/ia64/xen/time.c left in tree.
Auto-merging arch/arm64/kernel/Makefile
CONFLICT (content): Merge conflict in arch/arm64/kernel/Makefile
Auto-merging arch/arm64/Kconfig
Auto-merging arch/arm/xen/enlighten.c
CONFLICT (content): Merge conflict in arch/arm/xen/enlighten.c
Auto-merging arch/arm/Kconfig
CONFLICT (content): Merge conflict in arch/arm/Kconfig
Automatic merge failed; fix conflicts and then commit the result.


I presume that is mostly due to David's FIFO queue patches.

Could you kindly rebase it on top 3.14-rc1 and also tack on
Catalin Marinas Ack on the patches?

Thank you!

> 
> 
> Cheers,
> 
> Stefano
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel

Re: [Xen-devel] [PATCH v9 0/5] xen/arm/arm64: CONFIG_PARAVIRT and stolen ticks accounting

[Stefano Stabellini]

On Tue, 4 Feb 2014, Konrad Rzeszutek Wilk wrote:
> On Thu, Jan 09, 2014 at 06:15:07PM +0000, Stefano Stabellini wrote:
> > Hi all,
> > this patch series introduces stolen ticks accounting for Xen on ARM and
> > ARM64.
> > Stolen ticks are clocksource ticks that have been "stolen" from the cpu,
> > typically because Linux is running in a virtual machine and the vcpu has
> > been descheduled.
> > To account for these ticks we introduce CONFIG_PARAVIRT and pv_time_ops
> > so that we can make use of:
> > 
> > kernel/sched/cputime.c:steal_account_process_tick
> > 
> > 
> > Changes in v9:
> > - added back missing new files from patches;
> > - fix compilation on avr32 (remove patch #5, revert to previous version
> >   of patch #2).
> > 
> > 
> > 
> > Stefano Stabellini (5):
> >       xen: move xen_setup_runstate_info and get_runstate_snapshot to drivers/xen/time.c
> >       kernel: missing include in cputime.c
> >       arm: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
> >       arm64: introduce CONFIG_PARAVIRT, PARAVIRT_TIME_ACCOUNTING and pv_time_ops
> >       xen/arm: account for stolen ticks
> > 
> >  arch/arm/Kconfig                  |   20 ++++++++
> >  arch/arm/include/asm/paravirt.h   |   20 ++++++++
> >  arch/arm/kernel/Makefile          |    2 +
> >  arch/arm/kernel/paravirt.c        |   25 ++++++++++
> >  arch/arm/xen/enlighten.c          |   21 +++++++++
> >  arch/arm64/Kconfig                |   20 ++++++++
> >  arch/arm64/include/asm/paravirt.h |   20 ++++++++
> >  arch/arm64/kernel/Makefile        |    1 +
> >  arch/arm64/kernel/paravirt.c      |   25 ++++++++++
> >  arch/ia64/xen/time.c              |   48 +++----------------
> >  arch/x86/xen/time.c               |   76 +------------------------------
> >  drivers/xen/Makefile              |    2 +-
> >  drivers/xen/time.c                |   91 +++++++++++++++++++++++++++++++++++++
> >  include/xen/xen-ops.h             |    5 ++
> >  kernel/sched/cputime.c            |    3 ++
> >  15 files changed, 261 insertions(+), 118 deletions(-)
> >  create mode 100644 arch/arm/include/asm/paravirt.h
> >  create mode 100644 arch/arm/kernel/paravirt.c
> >  create mode 100644 arch/arm64/include/asm/paravirt.h
> >  create mode 100644 arch/arm64/kernel/paravirt.c
> >  create mode 100644 drivers/xen/time.c
> > 
> > 
> > git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git lost_ticks_9
> 
> I tried to merge it on top of 3.14-rc1 + stable/for-linus-3.14 (which
> has the revert of " xen/grant-table: Avoid m2p_override during mapping"
> 
> 
> And I get:
> konrad@phenom:~/linux$ git merge stefano/lost_ticks_9
> Auto-merging drivers/xen/Makefile
> CONFLICT (content): Merge conflict in drivers/xen/Makefile
> Auto-merging arch/x86/xen/time.c
> CONFLICT (modify/delete): arch/ia64/xen/time.c deleted in HEAD and
> modified in stefano/lost_ticks_9. Version stefano/lost_ticks_9 of
> arch/ia64/xen/time.c left in tree.
> Auto-merging arch/arm64/kernel/Makefile
> CONFLICT (content): Merge conflict in arch/arm64/kernel/Makefile
> Auto-merging arch/arm64/Kconfig
> Auto-merging arch/arm/xen/enlighten.c
> CONFLICT (content): Merge conflict in arch/arm/xen/enlighten.c
> Auto-merging arch/arm/Kconfig
> CONFLICT (content): Merge conflict in arch/arm/Kconfig
> Automatic merge failed; fix conflicts and then commit the result.

Sorry for the delay, the series rebased on 3.14-rc3 is available here:

git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git lost_ticks_10



> I presume that is mostly due to David's FIFO queue patches.
> 
> Could you kindly rebase it on top 3.14-rc1 and also tack on
> Catalin Marinas Ack on the patches?

I will.