x86: Add a sched_clock paravirt_op
PATCH 1/1 x86: Add a sched_clock paravirt_op
The tsc-based get_scheduled_cycles interface is not a good match for Xen's runstate accounting, which reports everything in nanoseconds.
This patch replaces this interface with a sched_clock interface, which matches both Xen and VMI's requirements.
In order to do this, we:
1. replace get_scheduled_cycles with sched_clock
2. hoist cycles_2_ns into a common header
3. update vmi accordingly
One thing to note: because sched_clock is implemented as a weak function in kernel/sched.c, we must define a real function in order to override this weak binding. This means the usual paravirt_ops technique of using an inline function won't work in this case.
[ This is against Andi's patch queue. It fixes the x86-64 build problem. ]
--- arch/i386/kernel/paravirt.c | 2 - arch/i386/kernel/sched-clock.c | 43 +++++++++++++---------------------- arch/i386/kernel/vmi.c | 2 - arch/i386/kernel/vmiclock.c | 6 ++-- include/asm-i386/paravirt.h | 7 ++++- include/asm-i386/sched-clock.h | 49 ++++++++++++++++++++++++++++++++++++++++ include/asm-i386/timer.h | 2 - include/asm-i386/vmi_time.h | 2 - include/asm-x86_64/timer.h | 2 - 9 files changed, 79 insertions(+), 36 deletions(-)
===================================================================
arch/i386/kernel/paravirt.c +1 -1
@@ -268,7 +268,7 @@ struct paravirt_ops paravirt_ops = { .write_msr = native_write_msr_safe, .read_tsc = native_read_tsc, .read_pmc = native_read_pmc, - .get_scheduled_cycles = native_read_tsc, + .sched_clock = native_sched_clock, .get_cpu_khz = native_calculate_cpu_khz, .load_tr_desc = native_load_tr_desc, .set_ldt = native_set_ldt,
===================================================================
arch/i386/kernel/sched-clock.c +17 -26
74 lines not on this page · raw message
===================================================================
arch/i386/kernel/vmi.c +1 -1
@@ -890,7 +890,7 @@ static inline int __init activate_vmi(vo paravirt_ops.setup_boot_clock = vmi_time_bsp_init; paravirt_ops.setup_secondary_clock = vmi_time_ap_init;#endif - paravirt_ops.get_scheduled_cycles = vmi_get_sched_cycles; + paravirt_ops.sched_clock = vmi_sched_clock; paravirt_ops.get_cpu_khz = vmi_cpu_khz;/* We have true wallclock functions; disable CMOS clock sync */
===================================================================
arch/i386/kernel/vmiclock.c +3 -3
@@ -65,9 +65,9 @@ int vmi_set_wallclock(unsigned long now) }/* paravirt_ops.get_scheduled_cycles = vmi_get_sched_cycles */ -unsigned long long vmi_get_sched_cycles (void ) -{ -return vmi_timer_ops.get_cycle_counter (VMI_CYCLES_AVAILABLE ); +unsigned long long vmi_sched_clock (void ) +{ +return cycles_2_ns (vmi_timer_ops.get_cycle_counter (VMI_CYCLES_AVAILABLE )); }/* paravirt_ops.get_cpu_khz = vmi_cpu_khz */
===================================================================
include/asm-i386/paravirt.h +5 -2
@@ -116,7 +116,7 @@ struct paravirt_opsu64 (*read_tsc)(void);u64 (*read_pmc)(void); -u64 (*get_scheduled_cycles)(void); +unsigned long long (*sched_clock)(void );unsigned long (*get_cpu_khz)(void );/* Segment descriptor handling */
@@ -573,7 +573,10 @@ static inline u64 paravirt_read_tsc(void#define rdtscll (val) (val = paravirt_read_tsc()) -#define get_scheduled_cycles (val) (val = paravirt_ops.get_scheduled_cycles()) +static inline unsigned long long paravirt_sched_clock (void ) +{ + return PVOP_CALL0(unsigned long long, sched_clock); +}#define calculate_cpu_khz () (paravirt_ops.get_cpu_khz())#define write_tsc (val1,val2) wrmsr(0x10, val1, val2)
===================================================================
include/asm-i386/sched-clock.h new file +49 -0
49 lines not on this page · raw message
===================================================================
include/asm-i386/timer.h +1 -1
@@ -2,6 +2,7 @@#define _ASMi386_TIMER_H#include <linux/init.h> #include <linux/pm.h> +#include <asm/sched-clock.h> #define TICK_SIZE (tick_nsec / 1000)
@@ -15,7 +16,6 @@ extern int recalibrate_cpu_khz(void);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
===================================================================
include/asm-i386/vmi_time.h +1 -1
@@ -49,7 +49,7 @@ extern void __init vmi_time_init(void);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 long vmi_sched_clock (void );extern unsigned long vmi_cpu_khz (void );#ifdef CONFIG_X86_LOCAL_APIC
===================================================================
include/asm-x86_64/timer.h +1 -1
@@ -1,1 +1,1 @@ -#define get_scheduled_cycles (x) rdtscll(x) +#include <asm-i386/sched-clock.h>