[RFC, PATCH 22/24] i386 Consolidate redundant timer code

From: Zachary Amsden
Date: Mon Mar 13 2006 - 13:13:56 EST

Isolate some of the non-VMI timer related changes in Linux. This patch
moves the cyc_2_ns conversion code into a common location, eliminating
redundant code in hpet and tsc timer implementations, and introduces
some macros that may be redefined by the sub-architecture to avoid
dependence on APIC routing, CMOS time sync, and testing for broken time
hardware (which presumably, does not happen in a virtual machine).

Signed-off-by: Dan Hecht <dhecht@xxxxxxxxxx>
Signed-off-by: Zachary Amsden <zach@xxxxxxxxxx>

Index: linux-2.6.16-rc6/arch/i386/kernel/apic.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/apic.c 2006-03-12 19:49:53.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/apic.c 2006-03-12 19:57:42.000000000 -0800
@@ -39,6 +39,7 @@

#include <mach_apic.h>
#include <mach_ipi.h>
+#include <mach_apictimer.h>

#include "io_ports.h"

@@ -1322,7 +1323,7 @@ int __init APIC_init_uniprocessor (void)
if (!skip_ioapic_setup && nr_ioapics)
setup_IO_APIC();
#endif
- setup_boot_APIC_clock();
+ mach_setup_boot_local_clock();

return 0;
}
Index: linux-2.6.16-rc6/arch/i386/kernel/i8259.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/i8259.c 2006-01-02 19:21:10.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/i8259.c 2006-03-12 19:57:42.000000000 -0800
@@ -425,7 +425,7 @@ void __init init_IRQ(void)
* Set the clock to HZ Hz, we already have a valid
* vector now:
*/
- setup_pit_timer();
+ setup_system_timer();

/*
* External FPU? Set up irq13 if so, for
Index: linux-2.6.16-rc6/arch/i386/kernel/io_apic.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/io_apic.c 2006-03-12 19:49:53.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/io_apic.c 2006-03-12 19:57:42.000000000 -0800
@@ -40,6 +40,7 @@
#include <asm/i8259.h>

#include <mach_apic.h>
+#include <mach_apictimer.h>

#include "io_ports.h"

@@ -1864,7 +1865,7 @@ static void __init setup_ioapic_ids_from
* - if this function detects that timer IRQs are defunct, then we fall
* back to ISA timer IRQs
*/
-static int __init timer_irq_works(void)
+int __init timer_irq_works(void)
{
unsigned long t1 = jiffies;

@@ -2285,7 +2286,7 @@ static inline void check_timer(void)
* Ok, does IRQ0 through the IOAPIC work?
*/
unmask_IO_APIC_irq(0);
- if (timer_irq_works()) {
+ if (mach_timer_irq_works()) {
if (nmi_watchdog == NMI_IO_APIC) {
disable_8259A_irq(0);
setup_nmi();
@@ -2307,7 +2308,7 @@ static inline void check_timer(void)
* legacy devices should be connected to IO APIC #0
*/
setup_ExtINT_IRQ0_pin(apic2, pin2, vector);
- if (timer_irq_works()) {
+ if (mach_timer_irq_works()) {
printk("works.\n");
if (pin1 != -1)
replace_pin_at_irq(0, apic1, pin1, apic2, pin2);
@@ -2337,7 +2338,7 @@ static inline void check_timer(void)
apic_write_around(APIC_LVT0, APIC_DM_FIXED | vector); /* Fixed mode */
enable_8259A_irq(0);

- if (timer_irq_works()) {
+ if (mach_timer_irq_works()) {
printk(" works.\n");
return;
}
@@ -2353,7 +2354,7 @@ static inline void check_timer(void)

unlock_ExtINT_logic();

- if (timer_irq_works()) {
+ if (mach_timer_irq_works()) {
printk(" works.\n");
return;
}
Index: linux-2.6.16-rc6/arch/i386/kernel/smpboot.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/smpboot.c 2006-03-12 19:57:32.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/smpboot.c 2006-03-12 19:57:42.000000000 -0800
@@ -56,6 +56,7 @@
#include <mach_apic.h>
#include <mach_wakecpu.h>
#include <smpboot_hooks.h>
+#include <mach_apictimer.h>

/* Set if we find a B stepping CPU */
static int __devinitdata smp_b_stepping;
@@ -513,7 +514,7 @@ static void __devinit start_secondary(vo
smp_callin();
while (!cpu_isset(smp_processor_id(), smp_commenced_mask))
rep_nop();
- setup_secondary_APIC_clock();
+ mach_setup_secondary_local_clock();
if (nmi_watchdog == NMI_IO_APIC) {
disable_8259A_irq(0);
enable_NMI_through_LVT0(NULL);
@@ -1270,7 +1271,7 @@ static void __init smp_boot_cpus(unsigne

smpboot_setup_io_apic();

- setup_boot_APIC_clock();
+ mach_setup_boot_local_clock();

/*
* Synchronize the TSC with the AP
Index: linux-2.6.16-rc6/arch/i386/kernel/time.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/time.c 2006-03-12 19:49:53.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/time.c 2006-03-12 19:57:42.000000000 -0800
@@ -329,6 +329,7 @@ unsigned long get_cmos_time(void)
}
EXPORT_SYMBOL(get_cmos_time);

+int no_sync_cmos_timer;
static void sync_cmos_clock(unsigned long dummy);

static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0);
@@ -375,7 +376,8 @@ static void sync_cmos_clock(unsigned lon

void notify_arch_cmos_timer(void)
{
- mod_timer(&sync_cmos_timer, jiffies + 1);
+ if (!no_sync_cmos_timer)
+ mod_timer(&sync_cmos_timer, jiffies + 1);
}

static long clock_cmos_diff, sleep_start;
@@ -446,16 +448,19 @@ static int time_init_device(void)

device_initcall(time_init_device);

-#ifdef CONFIG_HPET_TIMER
-extern void (*late_time_init)(void);
-/* Duplicate of time_init() below, with hpet_enable part added */
-static void __init hpet_time_init(void)
+void __init init_xtime_from_cmos(void)
{
xtime.tv_sec = get_cmos_time();
xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
+}

+#ifdef CONFIG_HPET_TIMER
+extern void (*late_time_init)(void);
+/* Duplicate of time_init() below, with hpet_enable part added */
+static void __init hpet_time_init(void)
+{
if ((hpet_enable() >= 0) && hpet_use_timer) {
printk("Using HPET for base-timer\n");
}
@@ -479,11 +484,6 @@ void __init time_init(void)
return;
}
#endif
- xtime.tv_sec = get_cmos_time();
- xtime.tv_nsec = (INITIAL_JIFFIES % HZ) * (NSEC_PER_SEC / HZ);
- set_normalized_timespec(&wall_to_monotonic,
- -xtime.tv_sec, -xtime.tv_nsec);
-
cur_timer = select_timer();
printk(KERN_INFO "Using %s for high-res timesource\n",cur_timer->name);

Index: linux-2.6.16-rc6/arch/i386/kernel/timers/common.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/timers/common.c 2006-01-02 19:21:10.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/timers/common.c 2006-03-12 19:57:42.000000000 -0800
@@ -14,6 +14,15 @@

#include "mach_timer.h"

+unsigned long cyc2ns_scale;
+unsigned long cyc2us_scale;
+
+void set_cyc_scales(unsigned long cpu_mhz)
+{
+ cyc2ns_scale = (1000 << CYC2NS_SCALE_FACTOR)/cpu_mhz;
+ cyc2us_scale = (1 << CYC2US_SCALE_FACTOR)/cpu_mhz;
+}
+
/* ------ Calibrate the TSC -------
* Return 2^32 * (1 / (TSC clocks per usec)) for do_fast_gettimeoffset().
* Too much 64-bit arithmetic here to do this cleanly in C, and for
Index: linux-2.6.16-rc6/arch/i386/kernel/timers/timer_cyclone.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/timers/timer_cyclone.c 2006-01-02 19:21:10.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/timers/timer_cyclone.c 2006-03-12 19:57:42.000000000 -0800
@@ -224,6 +224,7 @@ static int __init init_cyclone(char* ove
}
}

+ init_xtime_from_cmos();
init_cpu_khz();

/* Everything looks good! */
Index: linux-2.6.16-rc6/arch/i386/kernel/timers/timer_hpet.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/timers/timer_hpet.c 2006-01-02 19:21:10.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/timers/timer_hpet.c 2006-03-12 19:57:42.000000000 -0800
@@ -26,39 +26,6 @@ static unsigned long last_tsc_high; /*
static unsigned long long monotonic_base;
static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED;

-/* convert from cycles(64bits) => nanoseconds (64bits)
- * basic equation:
- * ns = cycles / (freq / ns_per_sec)
- * ns = cycles * (ns_per_sec / freq)
- * ns = cycles * (10^9 / (cpu_khz * 10^3))
- * ns = cycles * (10^6 / cpu_khz)
- *
- * Then we use scaling math (suggested by george@xxxxxxxxxx) to get:
- * ns = cycles * (10^6 * SC / cpu_khz) / SC
- * ns = cycles * cyc2ns_scale / SC
- *
- * And since SC is a constant power of two, we can convert the div
- * into a shift.
- *
- * We can use khz divisor instead of mhz to keep a better percision, since
- * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
- * (mathieu.desnoyers@xxxxxxxxxx)
- *
- * -johnstul@xxxxxxxxxx "math is hard, lets go shopping!"
- */
-static unsigned long cyc2ns_scale;
-#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
-
-static inline void set_cyc2ns_scale(unsigned long cpu_khz)
-{
- cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
-}
-
-static inline unsigned long long cycles_2_ns(unsigned long long cyc)
-{
- return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
-}
-
static unsigned long long monotonic_clock_hpet(void)
{
unsigned long long last_offset, this_offset, base;
@@ -155,6 +122,7 @@ static int __init init_hpet(char* overri
return -ENODEV;

printk("Using HPET for gettimeofday\n");
+ init_xtime_from_cmos();
if (cpu_has_tsc) {
unsigned long tsc_quotient = calibrate_tsc_hpet(&tsc_hpet_quotient);
if (tsc_quotient) {
@@ -168,7 +136,7 @@ static int __init init_hpet(char* overri
printk("Detected %u.%03u MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
}
- set_cyc2ns_scale(cpu_khz);
+ set_cyc_scales(cpu_khz);
}
/* set this only when cpu_has_tsc */
timer_hpet.read_timer = read_timer_tsc;
Index: linux-2.6.16-rc6/arch/i386/kernel/timers/timer_pit.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/timers/timer_pit.c 2006-01-02 19:21:10.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/timers/timer_pit.c 2006-03-12 19:57:42.000000000 -0800
@@ -27,6 +27,7 @@ static int __init init_pit(char* overrid
if (override[0] && strncmp(override,"pit",3))
printk(KERN_ERR "Warning: clock= override failed. Defaulting "
"to PIT\n");
+ init_xtime_from_cmos();
init_cpu_khz();
count_p = LATCH;
return 0;
Index: linux-2.6.16-rc6/arch/i386/kernel/timers/timer_pm.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/timers/timer_pm.c 2006-01-02 19:21:10.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/timers/timer_pm.c 2006-03-12 19:57:42.000000000 -0800
@@ -127,6 +127,7 @@ pm_good:
if (verify_pmtmr_rate() != 0)
return -ENODEV;

+ init_xtime_from_cmos();
init_cpu_khz();
return 0;
}
Index: linux-2.6.16-rc6/arch/i386/kernel/timers/timer_tsc.c
===================================================================
--- linux-2.6.16-rc6.orig/arch/i386/kernel/timers/timer_tsc.c 2006-03-12 19:49:53.000000000 -0800
+++ linux-2.6.16-rc6/arch/i386/kernel/timers/timer_tsc.c 2006-03-12 19:57:42.000000000 -0800
@@ -54,39 +54,6 @@ static int __init start_lost_tick_compen
}
late_initcall(start_lost_tick_compensation);

-/* convert from cycles(64bits) => nanoseconds (64bits)
- * basic equation:
- * ns = cycles / (freq / ns_per_sec)
- * ns = cycles * (ns_per_sec / freq)
- * ns = cycles * (10^9 / (cpu_khz * 10^3))
- * ns = cycles * (10^6 / cpu_khz)
- *
- * Then we use scaling math (suggested by george@xxxxxxxxxx) to get:
- * ns = cycles * (10^6 * SC / cpu_khz) / SC
- * ns = cycles * cyc2ns_scale / SC
- *
- * And since SC is a constant power of two, we can convert the div
- * into a shift.
- *
- * We can use khz divisor instead of mhz to keep a better percision, since
- * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
- * (mathieu.desnoyers@xxxxxxxxxx)
- *
- * -johnstul@xxxxxxxxxx "math is hard, lets go shopping!"
- */
-static unsigned long cyc2ns_scale;
-#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
-
-static inline void set_cyc2ns_scale(unsigned long cpu_khz)
-{
- cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
-}
-
-static inline unsigned long long cycles_2_ns(unsigned long long cyc)
-{
- return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
-}
-
static int count2; /* counter for mark_offset_tsc() */

/* Cached *multiplier* to convert TSC counts to microseconds.
@@ -305,7 +272,7 @@ time_cpufreq_notifier(struct notifier_bl
if (use_tsc) {
if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
fast_gettimeoffset_quotient = cpufreq_scale(fast_gettimeoffset_ref, freq->new, ref_freq);
- set_cyc2ns_scale(cpu_khz);
+ set_cyc_scales(cpu_khz);
}
}
#endif
@@ -540,6 +507,7 @@ static int __init init_tsc(char* overrid
}

if (tsc_quotient) {
+ init_xtime_from_cmos();
fast_gettimeoffset_quotient = tsc_quotient;
use_tsc = 1;
/*
@@ -558,7 +526,7 @@ static int __init init_tsc(char* overrid
printk("Detected %u.%03u MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
}
- set_cyc2ns_scale(cpu_khz);
+ set_cyc_scales(cpu_khz);
return 0;
}
}
Index: linux-2.6.16-rc6/include/asm-i386/timer.h
===================================================================
--- linux-2.6.16-rc6.orig/include/asm-i386/timer.h 2006-01-02 19:21:10.000000000 -0800
+++ linux-2.6.16-rc6/include/asm-i386/timer.h 2006-03-12 19:57:42.000000000 -0800
@@ -38,7 +38,9 @@ struct init_timer_opts {
extern struct timer_opts* __init select_timer(void);
extern void clock_fallback(void);
void setup_pit_timer(void);
+void init_xtime_from_cmos(void);

+extern int no_sync_cmos_timer;
/* Modifiers for buggy PIT handling */

extern int pit_latch_buggy;
@@ -67,4 +69,44 @@ extern unsigned long calibrate_tsc_hpet(
#ifdef CONFIG_X86_PM_TIMER
extern struct init_timer_opts timer_pmtmr_init;
#endif
+
+static inline void setup_system_timer(void)
+{
+ setup_pit_timer();
+}
+
+/* convert from cycles(64bits) => nanoseconds (64bits)
+ * basic equation:
+ * ns = cycles / (freq / ns_per_sec)
+ * ns = cycles * (ns_per_sec / freq)
+ * ns = cycles * (10^9 / (cpu_mhz * 10^6))
+ * ns = cycles * (10^3 / cpu_mhz)
+ *
+ * Then we use scaling math (suggested by george@xxxxxxxxxx) to get:
+ * ns = cycles * (10^3 * SC / cpu_mhz) / SC
+ * ns = cycles * cyc2ns_scale / SC
+ *
+ * And since SC is a constant power of two, we can convert the div
+ * into a shift.
+ * -johnstul@xxxxxxxxxx "math is hard, lets go shopping!"
+ */
+
+extern unsigned long cyc2ns_scale;
+extern unsigned long cyc2us_scale;
+
+#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
+#define CYC2US_SCALE_FACTOR 20
+
+extern void set_cyc_scales(unsigned long cpu_mhz);
+
+static inline unsigned long long cycles_2_ns(unsigned long long cyc)
+{
+ return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR;
+}
+
+static inline unsigned long long cycles_2_us(unsigned long long cyc)
+{
+ return (cyc * cyc2us_scale) >> CYC2US_SCALE_FACTOR;
+}
+
#endif
Index: linux-2.6.16-rc6/include/asm-i386/mach-default/mach_apictimer.h
===================================================================
--- linux-2.6.16-rc6.orig/include/asm-i386/mach-default/mach_apictimer.h 2006-03-12 19:57:42.000000000 -0800
+++ linux-2.6.16-rc6/include/asm-i386/mach-default/mach_apictimer.h 2006-03-12 19:57:42.000000000 -0800
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2005, VMware, Inc.
+ *
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * Send feedback to dhecht@xxxxxxxxxx
+ *
+ */
+
+/*
+ * Initiation routines related to the APIC timer.
+ * These may optionally be overridden by the subarchitecture in
+ * mach_apictimer.h.
+ */
+
+#ifndef __ASM_MACH_APICTIMER_H
+#define __ASM_MACH_APICTIMER_H
+
+#ifdef CONFIG_X86_LOCAL_APIC
+
+extern int __init timer_irq_works(void);
+
+static inline void mach_setup_boot_local_clock(void)
+{
+ setup_boot_APIC_clock();
+}
+
+static inline void mach_setup_secondary_local_clock(void)
+{
+ setup_secondary_APIC_clock();
+}
+
+static inline int mach_timer_irq_works(void)
+{
+ return timer_irq_works();
+}
+
+#endif /* CONFIG_X86_LOCAL_APIC */
+
+#endif /* __ASM_MACH_APICTIMER_H */
-
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