[PATCH] vmi: cpu cycles fix

1182d852 · Zachary Amsden <[email protected]> · 2007-03-05 00:30:36 -08:00

In order to share the common code in tsc.c which does CPU Khz calibration, we
need to make an accurate value of CPU speed available to the tsc.c code.  This
value loses a lot of precision in a VM because of the timing differences with
real hardware, but we need it to be as precise as possible so the guest can
make accurate time calculations with the cycle counters.

Signed-off-by: Zachary Amsden <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: 1182d8528b620c23d043bccbbef092b42062960a
Parents: 6cb9a835

Changes

7 files changed · +17 −2

File	Status	Add	Del	Content
arch/i386/kernel/paravirt.c	modified	+1	−0	View file
arch/i386/kernel/tsc.c	modified	+1	−1	View file
arch/i386/kernel/vmi.c	modified	+1	−0	View file
arch/i386/kernel/vmitime.c	modified	+9	−1	View file
include/asm-i386/paravirt.h	modified	+2	−0	View file
include/asm-i386/timer.h	modified	+2	−0	View file
include/asm-i386/vmi_time.h	modified	+1	−0	View file

arch/i386/kernel/paravirt.c

View file

diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
index 31bbe70..8352394 100644
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -522,6 +522,7 @@ struct paravirt_ops paravirt_ops = {
 	.read_tsc = native_read_tsc,
 	.read_pmc = native_read_pmc,
 	.get_scheduled_cycles = native_read_tsc,
+	.get_cpu_khz = native_calculate_cpu_khz,
 	.load_tr_desc = native_load_tr_desc,
 	.set_ldt = native_set_ldt,
 	.load_gdt = native_load_gdt,

arch/i386/kernel/tsc.c

View file

diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index c9c9d54..59222a0 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -117,7 +117,7 @@ unsigned long long sched_clock(void)
 	return cycles_2_ns(this_offset);
 }
 
-static unsigned long calculate_cpu_khz(void)
+unsigned long native_calculate_cpu_khz(void)
 {
 	unsigned long long start, end;
 	unsigned long count;

arch/i386/kernel/vmi.c

View file

diff --git a/arch/i386/kernel/vmi.c b/arch/i386/kernel/vmi.c
index 556b9a6..acdfe69 100644
--- a/arch/i386/kernel/vmi.c
+++ b/arch/i386/kernel/vmi.c
@@ -874,6 +874,7 @@ static inline int __init activate_vmi(void)
 		paravirt_ops.setup_secondary_clock = vmi_timer_setup_secondary_alarm;
 #endif
 		paravirt_ops.get_scheduled_cycles = vmi_get_sched_cycles;
+ 		paravirt_ops.get_cpu_khz = vmi_cpu_khz;
 	}
 	if (!disable_noidle)
 		para_fill(safe_halt, Halt);

arch/i386/kernel/vmitime.c

View file

diff --git a/arch/i386/kernel/vmitime.c b/arch/i386/kernel/vmitime.c
index f2aa8fa..4bb218e 100644
--- a/arch/i386/kernel/vmitime.c
+++ b/arch/i386/kernel/vmitime.c
@@ -177,6 +177,15 @@ unsigned long long vmi_get_sched_cycles(void)
 	return read_available_cycles();
 }
 
+unsigned long vmi_cpu_khz(void)
+{
+	unsigned long long khz;
+
+	khz = vmi_timer_ops.get_cycle_frequency();
+	(void)do_div(khz, 1000);
+	return khz;
+}
+
 void __init vmi_time_init(void)
 {
 	unsigned long long cycles_per_sec, cycles_per_msec;
@@ -206,7 +215,6 @@ void __init vmi_time_init(void)
 	(void)do_div(cycles_per_alarm, alarm_hz);
 	cycles_per_msec = cycles_per_sec;
 	(void)do_div(cycles_per_msec, 1000);
-	cpu_khz = cycles_per_msec;
 
 	printk(KERN_WARNING "VMI timer cycles/sec = %llu ; cycles/jiffy = %llu ;"
 	       "cycles/alarm = %llu\n", cycles_per_sec, cycles_per_jiffy,

include/asm-i386/paravirt.h

View file

diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index a132302..a35c814 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -95,6 +95,7 @@ struct paravirt_ops
 	u64 (*read_tsc)(void);
 	u64 (*read_pmc)(void);
  	u64 (*get_scheduled_cycles)(void);
+	unsigned long (*get_cpu_khz)(void);
 
 	void (*load_tr_desc)(void);
 	void (*load_gdt)(const struct Xgt_desc_struct *);
@@ -275,6 +276,7 @@ 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 calculate_cpu_khz() (paravirt_ops.get_cpu_khz())
 
 #define write_tsc(val1,val2) wrmsr(0x10, val1, val2)
 

include/asm-i386/timer.h

View file

diff --git a/include/asm-i386/timer.h b/include/asm-i386/timer.h
index d1f7b4f..12dd67b 100644
--- a/include/asm-i386/timer.h
+++ b/include/asm-i386/timer.h
@@ -7,6 +7,7 @@
 
 void setup_pit_timer(void);
 unsigned long long native_sched_clock(void);
+unsigned long native_calculate_cpu_khz(void);
 
 /* Modifiers for buggy PIT handling */
 extern int pit_latch_buggy;
@@ -17,6 +18,7 @@ extern int recalibrate_cpu_khz(void);
 
 #ifndef CONFIG_PARAVIRT
 #define get_scheduled_cycles(val) rdtscll(val)
+#define calculate_cpu_khz() native_calculate_cpu_khz()
 #endif
 
 #endif

include/asm-i386/vmi_time.h

View file

diff --git a/include/asm-i386/vmi_time.h b/include/asm-i386/vmi_time.h
index f59c35d..1f971eb 100644
--- a/include/asm-i386/vmi_time.h
+++ b/include/asm-i386/vmi_time.h
@@ -50,6 +50,7 @@ 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_get_sched_cycles(void);
+extern unsigned long vmi_cpu_khz(void);
 
 #ifdef CONFIG_X86_LOCAL_APIC
 extern void __init vmi_timer_setup_boot_alarm(void);