kernel-fxtec-pro1x/arch/x86/kernel/tsc_32.c

407 lines
9 KiB
C
Raw Normal View History

#include <linux/sched.h>
#include <linux/clocksource.h>
#include <linux/workqueue.h>
#include <linux/cpufreq.h>
#include <linux/jiffies.h>
#include <linux/init.h>
#include <linux/dmi.h>
#include <asm/delay.h>
#include <asm/tsc.h>
#include <asm/io.h>
#include <asm/timer.h>
#include "mach_timer.h"
static int tsc_enabled;
/*
* On some systems the TSC frequency does not
* change with the cpu frequency. So we need
* an extra value to store the TSC freq
*/
unsigned int tsc_khz;
EXPORT_SYMBOL_GPL(tsc_khz);
int tsc_disable;
#ifdef CONFIG_X86_TSC
static int __init tsc_setup(char *str)
{
printk(KERN_WARNING "notsc: Kernel compiled with CONFIG_X86_TSC, "
"cannot disable TSC.\n");
return 1;
}
#else
/*
* disable flag for tsc. Takes effect by clearing the TSC cpu flag
* in cpu/common.c
*/
static int __init tsc_setup(char *str)
{
tsc_disable = 1;
return 1;
}
#endif
__setup("notsc", tsc_setup);
/*
* code to mark and check if the TSC is unstable
* due to cpufreq or due to unsynced TSCs
*/
static int tsc_unstable;
int check_tsc_unstable(void)
{
return tsc_unstable;
}
EXPORT_SYMBOL_GPL(check_tsc_unstable);
/* Accelerators for sched_clock()
* 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@mvista.com) 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 precision, since
* cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits.
* (mathieu.desnoyers@polymtl.ca)
*
* -johnstul@us.ibm.com "math is hard, lets go shopping!"
*/
unsigned long cyc2ns_scale __read_mostly;
#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;
}
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long native_sched_clock(void)
{
unsigned long long this_offset;
/*
* Fall back to jiffies if there's no TSC available:
* ( But note that we still use it if the TSC is marked
* unstable. We do this because unlike Time Of Day,
* the scheduler clock tolerates small errors and it's
* very important for it to be as fast as the platform
* can achive it. )
*/
if (unlikely(!tsc_enabled && !tsc_unstable))
/* No locking but a rare wrong value is not a big deal: */
return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
/* read the Time Stamp Counter: */
rdtscll(this_offset);
/* return the value in ns */
return cycles_2_ns(this_offset);
}
/* We need to define a real function for sched_clock, to override the
weak default version */
#ifdef CONFIG_PARAVIRT
unsigned long long sched_clock(void)
{
return paravirt_sched_clock();
}
#else
unsigned long long sched_clock(void)
__attribute__((alias("native_sched_clock")));
#endif
unsigned long native_calculate_cpu_khz(void)
{
unsigned long long start, end;
unsigned long count;
x86: fix TSC clock source calibration error I ran into this problem on a system that was unable to obtain NTP sync because the clock was running very slow (over 10000ppm slow). ntpd had declared all of its peers 'reject' with 'peer_dist' reason. On investigation, the tsc_khz variable was significantly incorrect causing xtime to run slow. After a reboot tsc_khz was correct so I did a reboot test to see how often the problem occurred: Test was done on a 2000 Mhz Xeon system. Of 689 reboots, 8 of them had unacceptable tsc_khz values (>500ppm): range of tsc_khz # of boots % of boots ---------------- ---------- ---------- < 1999750 0 0.000% 1999750 - 1999800 21 3.048% 1999800 - 1999850 166 24.128% 1999850 - 1999900 241 35.029% 1999900 - 1999950 211 30.669% 1999950 - 2000000 42 6.105% 2000000 - 2000000 0 0.000% 2000050 - 2000100 0 0.000% [...] 2000100 - 2015000 1 0.145% << BAD 2015000 - 2030000 6 0.872% << BAD 2030000 - 2045000 1 0.145% << BAD 2045000 < 0 0.000% The worst boot was 2032.577 Mhz, over 1.5% off! It appears that on rare occasions, mach_countup() is taking longer to complete than necessary. I suspect that this is caused by the CPU taking a periodic SMI interrupt right at the end of the 30ms calibration loop. This would cause the loop to delay while the SMI BIOS hander runs. The resulting TSC value is beyond what it actually should be resulting in a higher tsc_khz. The below patch makes native_calculate_cpu_khz() take the best (shortest duration, lowest khz) run of it's 3 calibration loops. If a SMI goes off causing a bad result (long duration, higher khz) it will be discarded. With the patch applied, 300 boots of the same system produce good results: range of tsc_khz # of boots % of boots ---------------- ---------- ---------- < 1999750 0 0.000% 1999750 - 1999800 30 10.000% 1999800 - 1999850 166 55.333% 1999850 - 1999900 89 29.667% 1999900 - 1999950 15 5.000% 1999950 < 0 0.000% Problem was found and tested against 2.6.18. Patch is against 2.6.22. Signed-off-by: Dave Johnson <djohnson@sw.starentnetworks.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-23 14:37:22 -06:00
u64 delta64 = (u64)ULLONG_MAX;
int i;
unsigned long flags;
local_irq_save(flags);
/* run 3 times to ensure the cache is warm */
for (i = 0; i < 3; i++) {
mach_prepare_counter();
rdtscll(start);
mach_countup(&count);
rdtscll(end);
x86: fix TSC clock source calibration error I ran into this problem on a system that was unable to obtain NTP sync because the clock was running very slow (over 10000ppm slow). ntpd had declared all of its peers 'reject' with 'peer_dist' reason. On investigation, the tsc_khz variable was significantly incorrect causing xtime to run slow. After a reboot tsc_khz was correct so I did a reboot test to see how often the problem occurred: Test was done on a 2000 Mhz Xeon system. Of 689 reboots, 8 of them had unacceptable tsc_khz values (>500ppm): range of tsc_khz # of boots % of boots ---------------- ---------- ---------- < 1999750 0 0.000% 1999750 - 1999800 21 3.048% 1999800 - 1999850 166 24.128% 1999850 - 1999900 241 35.029% 1999900 - 1999950 211 30.669% 1999950 - 2000000 42 6.105% 2000000 - 2000000 0 0.000% 2000050 - 2000100 0 0.000% [...] 2000100 - 2015000 1 0.145% << BAD 2015000 - 2030000 6 0.872% << BAD 2030000 - 2045000 1 0.145% << BAD 2045000 < 0 0.000% The worst boot was 2032.577 Mhz, over 1.5% off! It appears that on rare occasions, mach_countup() is taking longer to complete than necessary. I suspect that this is caused by the CPU taking a periodic SMI interrupt right at the end of the 30ms calibration loop. This would cause the loop to delay while the SMI BIOS hander runs. The resulting TSC value is beyond what it actually should be resulting in a higher tsc_khz. The below patch makes native_calculate_cpu_khz() take the best (shortest duration, lowest khz) run of it's 3 calibration loops. If a SMI goes off causing a bad result (long duration, higher khz) it will be discarded. With the patch applied, 300 boots of the same system produce good results: range of tsc_khz # of boots % of boots ---------------- ---------- ---------- < 1999750 0 0.000% 1999750 - 1999800 30 10.000% 1999800 - 1999850 166 55.333% 1999850 - 1999900 89 29.667% 1999900 - 1999950 15 5.000% 1999950 < 0 0.000% Problem was found and tested against 2.6.18. Patch is against 2.6.22. Signed-off-by: Dave Johnson <djohnson@sw.starentnetworks.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-23 14:37:22 -06:00
delta64 = min(delta64, (end - start));
}
/*
* Error: ECTCNEVERSET
* The CTC wasn't reliable: we got a hit on the very first read,
* or the CPU was so fast/slow that the quotient wouldn't fit in
* 32 bits..
*/
if (count <= 1)
goto err;
/* cpu freq too fast: */
if (delta64 > (1ULL<<32))
goto err;
/* cpu freq too slow: */
if (delta64 <= CALIBRATE_TIME_MSEC)
goto err;
delta64 += CALIBRATE_TIME_MSEC/2; /* round for do_div */
do_div(delta64,CALIBRATE_TIME_MSEC);
local_irq_restore(flags);
return (unsigned long)delta64;
err:
local_irq_restore(flags);
return 0;
}
int recalibrate_cpu_khz(void)
{
#ifndef CONFIG_SMP
unsigned long cpu_khz_old = cpu_khz;
if (cpu_has_tsc) {
cpu_khz = calculate_cpu_khz();
tsc_khz = cpu_khz;
cpu_data(0).loops_per_jiffy =
cpufreq_scale(cpu_data(0).loops_per_jiffy,
cpu_khz_old, cpu_khz);
return 0;
} else
return -ENODEV;
#else
return -ENODEV;
#endif
}
EXPORT_SYMBOL(recalibrate_cpu_khz);
#ifdef CONFIG_CPU_FREQ
/*
* if the CPU frequency is scaled, TSC-based delays will need a different
* loops_per_jiffy value to function properly.
*/
static unsigned int ref_freq = 0;
static unsigned long loops_per_jiffy_ref = 0;
static unsigned long cpu_khz_ref = 0;
static int
time_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
{
struct cpufreq_freqs *freq = data;
if (!ref_freq) {
if (!freq->old){
ref_freq = freq->new;
return 0;
}
ref_freq = freq->old;
loops_per_jiffy_ref = cpu_data(freq->cpu).loops_per_jiffy;
cpu_khz_ref = cpu_khz;
}
if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
(val == CPUFREQ_RESUMECHANGE)) {
if (!(freq->flags & CPUFREQ_CONST_LOOPS))
cpu_data(freq->cpu).loops_per_jiffy =
cpufreq_scale(loops_per_jiffy_ref,
ref_freq, freq->new);
if (cpu_khz) {
if (num_online_cpus() == 1)
cpu_khz = cpufreq_scale(cpu_khz_ref,
ref_freq, freq->new);
if (!(freq->flags & CPUFREQ_CONST_LOOPS)) {
tsc_khz = cpu_khz;
set_cyc2ns_scale(cpu_khz);
/*
* TSC based sched_clock turns
* to junk w/ cpufreq
*/
mark_tsc_unstable("cpufreq changes");
}
}
}
return 0;
}
static struct notifier_block time_cpufreq_notifier_block = {
.notifier_call = time_cpufreq_notifier
};
static int __init cpufreq_tsc(void)
{
return cpufreq_register_notifier(&time_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
}
core_initcall(cpufreq_tsc);
#endif
/* clock source code */
static unsigned long current_tsc_khz = 0;
static cycle_t read_tsc(void)
{
cycle_t ret;
rdtscll(ret);
return ret;
}
static struct clocksource clocksource_tsc = {
.name = "tsc",
.rating = 300,
.read = read_tsc,
.mask = CLOCKSOURCE_MASK(64),
.mult = 0, /* to be set */
.shift = 22,
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_MUST_VERIFY,
};
void mark_tsc_unstable(char *reason)
{
if (!tsc_unstable) {
tsc_unstable = 1;
tsc_enabled = 0;
printk("Marking TSC unstable due to: %s.\n", reason);
/* Can be called before registration */
if (clocksource_tsc.mult)
clocksource_change_rating(&clocksource_tsc, 0);
else
clocksource_tsc.rating = 0;
}
}
EXPORT_SYMBOL_GPL(mark_tsc_unstable);
static int __init dmi_mark_tsc_unstable(const struct dmi_system_id *d)
{
printk(KERN_NOTICE "%s detected: marking TSC unstable.\n",
d->ident);
tsc_unstable = 1;
return 0;
}
/* List of systems that have known TSC problems */
static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
{
.callback = dmi_mark_tsc_unstable,
.ident = "IBM Thinkpad 380XD",
.matches = {
DMI_MATCH(DMI_BOARD_VENDOR, "IBM"),
DMI_MATCH(DMI_BOARD_NAME, "2635FA0"),
},
},
{}
};
/*
* Make an educated guess if the TSC is trustworthy and synchronized
* over all CPUs.
*/
__cpuinit int unsynchronized_tsc(void)
{
if (!cpu_has_tsc || tsc_unstable)
return 1;
/*
* Intel systems are normally all synchronized.
* Exceptions must mark TSC as unstable:
*/
if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
/* assume multi socket systems are not synchronized: */
if (num_possible_cpus() > 1)
tsc_unstable = 1;
}
return tsc_unstable;
}
/*
* Geode_LX - the OLPC CPU has a possibly a very reliable TSC
*/
#ifdef CONFIG_MGEODE_LX
/* RTSC counts during suspend */
#define RTSC_SUSP 0x100
static void __init check_geode_tsc_reliable(void)
{
x86: do not crash on non-Geode PCs in TSC probe with this fix Geode kernels can be booted (and QA-ed) on generic PCs. otherwise it crashes and burns during early bootup: Detected 2160.212 MHz processor. general protection fault: 0000 [#1] PREEMPT SMP Modules linked in: CPU: 0 EIP: 0060:[<c09071f6>] Not tainted VLI EFLAGS: 00010002 (2.6.23-rc9 #90) EIP is at tsc_init+0xa6/0x150 eax: 00000001 ebx: c1dce000 ecx: 00001900 edx: 00000001 esi: 00051000 edi: 00051000 ebp: c08fdfc4 esp: c08fdfa4 ds: 007b es: 007b fs: 00d8 gs: 0000 ss: 0068 Process swapper (pid: 0, ti=c08fc000 task=c082a180 task.ti=c08fc000) Stack: c076b870 00000870 000000d4 0000001d c0831e80 c1dce000 00051000 00051000 c08fdfcc c09053f8 c08fdff8 c09045ff 000001e2 c09040a0 00051000 00000020 0004e500 c0932140 00020800 00099800 c08ed000 01409007 00000000 Call Trace: [<c010517a>] show_trace_log_lvl+0x1a/0x30 [<c0105246>] show_stack_log_lvl+0xb6/0x100 [<c0105732>] show_registers+0x212/0x3a0 [<c0105aa4>] die+0x104/0x220 [<c0105f5f>] do_general_protection+0x1ef/0x2b0 [<c06699f2>] error_code+0x72/0x78 [<c09053f8>] time_init+0x8/0x20 [<c09045ff>] start_kernel+0x1af/0x320 [<00000000>] 0x0 ======================= Code: 31 d2 b8 00 00 09 3d f7 35 2c 70 9b c0 a3 04 95 8f c0 e8 ce 4e 99 ff b8 e0 45 93 c0 e8 94 b1 c5 ff e8 7f 3d 80 ff b9 00 19 00 00 <0f> 32 f6 c4 01 74 07 83 25 24 ce 82 c0 fd 8b 0d 20 ce 82 c0 b8 EIP: [<c09071f6>] tsc_init+0xa6/0x150 SS:ESP 0068:c08fdfa4 Kernel panic - not syncing: Attempted to kill the idle task! Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-17 10:04:34 -06:00
unsigned long res_low, res_high;
x86: do not crash on non-Geode PCs in TSC probe with this fix Geode kernels can be booted (and QA-ed) on generic PCs. otherwise it crashes and burns during early bootup: Detected 2160.212 MHz processor. general protection fault: 0000 [#1] PREEMPT SMP Modules linked in: CPU: 0 EIP: 0060:[<c09071f6>] Not tainted VLI EFLAGS: 00010002 (2.6.23-rc9 #90) EIP is at tsc_init+0xa6/0x150 eax: 00000001 ebx: c1dce000 ecx: 00001900 edx: 00000001 esi: 00051000 edi: 00051000 ebp: c08fdfc4 esp: c08fdfa4 ds: 007b es: 007b fs: 00d8 gs: 0000 ss: 0068 Process swapper (pid: 0, ti=c08fc000 task=c082a180 task.ti=c08fc000) Stack: c076b870 00000870 000000d4 0000001d c0831e80 c1dce000 00051000 00051000 c08fdfcc c09053f8 c08fdff8 c09045ff 000001e2 c09040a0 00051000 00000020 0004e500 c0932140 00020800 00099800 c08ed000 01409007 00000000 Call Trace: [<c010517a>] show_trace_log_lvl+0x1a/0x30 [<c0105246>] show_stack_log_lvl+0xb6/0x100 [<c0105732>] show_registers+0x212/0x3a0 [<c0105aa4>] die+0x104/0x220 [<c0105f5f>] do_general_protection+0x1ef/0x2b0 [<c06699f2>] error_code+0x72/0x78 [<c09053f8>] time_init+0x8/0x20 [<c09045ff>] start_kernel+0x1af/0x320 [<00000000>] 0x0 ======================= Code: 31 d2 b8 00 00 09 3d f7 35 2c 70 9b c0 a3 04 95 8f c0 e8 ce 4e 99 ff b8 e0 45 93 c0 e8 94 b1 c5 ff e8 7f 3d 80 ff b9 00 19 00 00 <0f> 32 f6 c4 01 74 07 83 25 24 ce 82 c0 fd 8b 0d 20 ce 82 c0 b8 EIP: [<c09071f6>] tsc_init+0xa6/0x150 SS:ESP 0068:c08fdfa4 Kernel panic - not syncing: Attempted to kill the idle task! Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-17 10:04:34 -06:00
rdmsr_safe(MSR_GEODE_BUSCONT_CONF0, &res_low, &res_high);
if (res_low & RTSC_SUSP)
clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
}
#else
static inline void check_geode_tsc_reliable(void) { }
#endif
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
void __init tsc_init(void)
{
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
if (!cpu_has_tsc || tsc_disable)
goto out_no_tsc;
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
cpu_khz = calculate_cpu_khz();
tsc_khz = cpu_khz;
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
if (!cpu_khz)
goto out_no_tsc;
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
printk("Detected %lu.%03lu MHz processor.\n",
(unsigned long)cpu_khz / 1000,
(unsigned long)cpu_khz % 1000);
set_cyc2ns_scale(cpu_khz);
use_tsc_delay();
/* Check and install the TSC clocksource */
dmi_check_system(bad_tsc_dmi_table);
unsynchronized_tsc();
check_geode_tsc_reliable();
current_tsc_khz = tsc_khz;
clocksource_tsc.mult = clocksource_khz2mult(current_tsc_khz,
clocksource_tsc.shift);
/* lower the rating if we already know its unstable: */
if (check_tsc_unstable()) {
clocksource_tsc.rating = 0;
clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
} else
tsc_enabled = 1;
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
clocksource_register(&clocksource_tsc);
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
return;
[PATCH] clocksource init adjustments (fix bug #7426) This patch resolves the issue found here: http://bugme.osdl.org/show_bug.cgi?id=7426 The basic summary is: Currently we register most of i386/x86_64 clocksources at module_init time. Then we enable clocksource selection at late_initcall time. This causes some problems for drivers that use gettimeofday for init calibration routines (specifically the es1968 driver in this case), where durring module_init, the only clocksource available is the low-res jiffies clocksource. This may cause slight calibration errors, due to the small sampling time used. It should be noted that drivers that require fine grained time may not function on architectures that do not have better then jiffies resolution timekeeping (there are a few). However, this does not discount the reasonable need for such fine-grained timekeeping at init time. Thus the solution here is to register clocksources earlier (ideally when the hardware is being initialized), and then we enable clocksource selection at fs_initcall (before device_initcall). This patch should probably get some testing time in -mm, since clocksource selection is one of the most important issues for correct timekeeping, and I've only been able to test this on a few of my own boxes. Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-03-05 01:30:50 -07:00
out_no_tsc:
/*
* Set the tsc_disable flag if there's no TSC support, this
* makes it a fast flag for the kernel to see whether it
* should be using the TSC.
*/
tsc_disable = 1;
}