Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6cb9a8350aee789100a365794272ed20cc8f2401
Commit: 6cb9a8350aee789100a365794272ed20cc8f2401
Parent: 7507ba34e827ca3c6bbcd34d20a8df8ba365fca6
Author: Zachary Amsden <[EMAIL PROTECTED]>
AuthorDate: Mon Mar 5 00:30:35 2007 -0800
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Mar 5 07:57:52 2007 -0800
[PATCH] vmi: sched clock paravirt op fix
The custom_sched_clock hook is broken. The result from sched_clock needs to
be in nanoseconds, not in CPU cycles. The TSC is insufficient for this
purpose, because TSC is poorly defined in a virtual environment, and mostly
represents real world time instead of scheduled process time (which can be
interrupted without notice when a virtual machine is descheduled).
To make the scheduler consistent, we must expose a different nature of time,
that is scheduled time. So deprecate this custom_sched_clock hack and turn
it
into a paravirt-op, as it should have been all along. This allows the tsc.c
code which converts cycles to nanoseconds to be shared by all paravirt-ops
backends.
It is unfortunate to add a new paravirt-op, but this is a very distinct
abstraction which is clearly different for all virtual machine
implementations, and it gets rid of an ugly indirect function which I
ashamedly admit I hacked in to try to get this to work earlier, and then
even
got in the wrong units.
Signed-off-by: Zachary Amsden <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
arch/i386/kernel/paravirt.c | 2 ++
arch/i386/kernel/tsc.c | 6 ++----
arch/i386/kernel/vmi.c | 2 +-
arch/i386/kernel/vmitime.c | 2 +-
include/asm-i386/paravirt.h | 3 +++
include/asm-i386/time.h | 1 -
include/asm-i386/timer.h | 8 +++++++-
include/asm-i386/vmi_time.h | 2 +-
8 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
index c156ecf..31bbe70 100644
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -32,6 +32,7 @@
#include <asm/fixmap.h>
#include <asm/apic.h>
#include <asm/tlbflush.h>
+#include <asm/timer.h>
/* nop stub */
static void native_nop(void)
@@ -520,6 +521,7 @@ struct paravirt_ops paravirt_ops = {
.write_msr = native_write_msr,
.read_tsc = native_read_tsc,
.read_pmc = native_read_pmc,
+ .get_scheduled_cycles = native_read_tsc,
.load_tr_desc = native_load_tr_desc,
.set_ldt = native_set_ldt,
.load_gdt = native_load_gdt,
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index 3082a41..c9c9d54 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -14,6 +14,7 @@
#include <asm/delay.h>
#include <asm/tsc.h>
#include <asm/io.h>
+#include <asm/timer.h>
#include "mach_timer.h"
@@ -102,9 +103,6 @@ unsigned long long sched_clock(void)
{
unsigned long long this_offset;
- if (unlikely(custom_sched_clock))
- return (*custom_sched_clock)();
-
/*
* Fall back to jiffies if there's no TSC available:
*/
@@ -113,7 +111,7 @@ unsigned long long sched_clock(void)
return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
/* read the Time Stamp Counter: */
- rdtscll(this_offset);
+ get_scheduled_cycles(this_offset);
/* return the value in ns */
return cycles_2_ns(this_offset);
diff --git a/arch/i386/kernel/vmi.c b/arch/i386/kernel/vmi.c
index 8417f74..556b9a6 100644
--- a/arch/i386/kernel/vmi.c
+++ b/arch/i386/kernel/vmi.c
@@ -873,7 +873,7 @@ static inline int __init activate_vmi(void)
paravirt_ops.setup_boot_clock = vmi_timer_setup_boot_alarm;
paravirt_ops.setup_secondary_clock =
vmi_timer_setup_secondary_alarm;
#endif
- custom_sched_clock = vmi_sched_clock;
+ paravirt_ops.get_scheduled_cycles = vmi_get_sched_cycles;
}
if (!disable_noidle)
para_fill(safe_halt, Halt);
diff --git a/arch/i386/kernel/vmitime.c b/arch/i386/kernel/vmitime.c
index 694aa85..f2aa8fa 100644
--- a/arch/i386/kernel/vmitime.c
+++ b/arch/i386/kernel/vmitime.c
@@ -172,7 +172,7 @@ int vmi_set_wallclock(unsigned long now)
return -1;
}
-unsigned long long vmi_sched_clock(void)
+unsigned long long vmi_get_sched_cycles(void)
{
return read_available_cycles();
}
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index 6317e0a..a132302 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -94,6 +94,7 @@ struct paravirt_ops
u64 (*read_tsc)(void);
u64 (*read_pmc)(void);
+ u64 (*get_scheduled_cycles)(void);
void (*load_tr_desc)(void);
void (*load_gdt)(const struct Xgt_desc_struct *);
@@ -273,6 +274,8 @@ static inline void halt(void)
#define rdtscll(val) (val = paravirt_ops.read_tsc())
+#define get_scheduled_cycles(val) (val = paravirt_ops.get_scheduled_cycles())
+
#define write_tsc(val1,val2) wrmsr(0x10, val1, val2)
#define rdpmc(counter,low,high) do { \
diff --git a/include/asm-i386/time.h b/include/asm-i386/time.h
index 571b429..ea8065a 100644
--- a/include/asm-i386/time.h
+++ b/include/asm-i386/time.h
@@ -30,7 +30,6 @@ static inline int native_set_wallclock(unsigned long nowtime)
#ifdef CONFIG_PARAVIRT
#include <asm/paravirt.h>
-extern unsigned long long native_sched_clock(void);
#else /* !CONFIG_PARAVIRT */
#define get_wallclock() native_get_wallclock()
diff --git a/include/asm-i386/timer.h b/include/asm-i386/timer.h
index 4752c3a..d1f7b4f 100644
--- a/include/asm-i386/timer.h
+++ b/include/asm-i386/timer.h
@@ -4,13 +4,19 @@
#include <linux/pm.h>
#define TICK_SIZE (tick_nsec / 1000)
+
void setup_pit_timer(void);
+unsigned long long native_sched_clock(void);
+
/* Modifiers for buggy PIT handling */
extern int pit_latch_buggy;
extern int timer_ack;
extern int no_timer_check;
-extern unsigned long long (*custom_sched_clock)(void);
extern int no_sync_cmos_clock;
extern int recalibrate_cpu_khz(void);
+#ifndef CONFIG_PARAVIRT
+#define get_scheduled_cycles(val) rdtscll(val)
+#endif
+
#endif
diff --git a/include/asm-i386/vmi_time.h b/include/asm-i386/vmi_time.h
index c129312..f59c35d 100644
--- a/include/asm-i386/vmi_time.h
+++ b/include/asm-i386/vmi_time.h
@@ -49,7 +49,7 @@ extern struct vmi_timer_ops {
extern void __init vmi_time_init(void);
extern unsigned long vmi_get_wallclock(void);
extern int vmi_set_wallclock(unsigned long now);
-extern unsigned long long vmi_sched_clock(void);
+extern unsigned long long vmi_get_sched_cycles(void);
#ifdef CONFIG_X86_LOCAL_APIC
extern void __init vmi_timer_setup_boot_alarm(void);
-
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