add sched_clock() hook to paravirtualize sched_clock().
ia64 sched_clock() is based on ar.itc which isn't stable
on virtualized environment because vcpu may move around on
pcpus. So it needs paravirtualization.
Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
---
arch/ia64/include/asm/paravirt.h | 7 +++++++
arch/ia64/include/asm/timex.h | 1 +
arch/ia64/kernel/head.S | 4 ++--
arch/ia64/kernel/paravirt.c | 1 +
arch/ia64/kernel/time.c | 12 ++++++++++++
5 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/arch/ia64/include/asm/paravirt.h b/arch/ia64/include/asm/paravirt.h
index 56f69f9..a73e77a 100644
--- a/arch/ia64/include/asm/paravirt.h
+++ b/arch/ia64/include/asm/paravirt.h
@@ -225,6 +225,8 @@ struct pv_time_ops {
int (*do_steal_accounting)(unsigned long *new_itm);
void (*clocksource_resume)(void);
+
+ unsigned long long (*sched_clock)(void);
};
extern struct pv_time_ops pv_time_ops;
@@ -242,6 +244,11 @@ paravirt_do_steal_accounting(unsigned long *new_itm)
return pv_time_ops.do_steal_accounting(new_itm);
}
+static inline unsigned long long paravirt_sched_clock(void)
+{
+ return pv_time_ops.sched_clock();
+}
+
#endif /* !__ASSEMBLY__ */
#else
diff --git a/arch/ia64/include/asm/timex.h b/arch/ia64/include/asm/timex.h
index 4e03cfe..86c7db8 100644
--- a/arch/ia64/include/asm/timex.h
+++ b/arch/ia64/include/asm/timex.h
@@ -40,5 +40,6 @@ get_cycles (void)
}
extern void ia64_cpu_local_tick (void);
+extern unsigned long long ia64_native_sched_clock (void);
#endif /* _ASM_IA64_TIMEX_H */
diff --git a/arch/ia64/kernel/head.S b/arch/ia64/kernel/head.S
index 66e491d..ca1336a 100644
--- a/arch/ia64/kernel/head.S
+++ b/arch/ia64/kernel/head.S
@@ -1050,7 +1050,7 @@ END(ia64_delay_loop)
* except that the multiplication and the shift are done with 128-bit
* intermediate precision so that we can produce a full 64-bit result.
*/
-GLOBAL_ENTRY(sched_clock)
+GLOBAL_ENTRY(ia64_native_sched_clock)
addl r8=THIS_CPU(cpu_info) + IA64_CPUINFO_NSEC_PER_CYC_OFFSET,r0
mov.m r9=ar.itc // fetch cycle-counter (35 cyc)
;;
@@ -1066,7 +1066,7 @@ GLOBAL_ENTRY(sched_clock)
;;
shrp r8=r9,r8,IA64_NSEC_PER_CYC_SHIFT
br.ret.sptk.many rp
-END(sched_clock)
+END(ia64_native_sched_clock)
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
GLOBAL_ENTRY(cycle_to_cputime)
diff --git a/arch/ia64/kernel/paravirt.c b/arch/ia64/kernel/paravirt.c
index de35d8e..6ebbcc1 100644
--- a/arch/ia64/kernel/paravirt.c
+++ b/arch/ia64/kernel/paravirt.c
@@ -366,4 +366,5 @@ ia64_native_do_steal_accounting(unsigned long *new_itm)
struct pv_time_ops pv_time_ops = {
.do_steal_accounting = ia64_native_do_steal_accounting,
+ .sched_clock = ia64_native_sched_clock,
};
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 65c10a4..6f6ca42 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -50,6 +50,18 @@ EXPORT_SYMBOL(last_cli_ip);
#endif
#ifdef CONFIG_PARAVIRT
+/* We need to define a real function for sched_clock, to override the
+ weak default version */
+unsigned long long sched_clock(void)
+{
+ return paravirt_sched_clock();
+}
+#else
+unsigned long long
+sched_clock(void) __attribute__((alias("ia64_native_sched_clock")));
+#endif
+
+#ifdef CONFIG_PARAVIRT
static void
paravirt_clocksource_resume(void)
{
--
1.6.0.2
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