[PATCH 1/2] non-string based tsc unstable reasons

Daniel Walker
2007-05-12T15:45:22Z

[-- Attachment #1: mark-tsc-unstable-reasons.patch --]
[-- Type: text/plain, Size: 9356 bytes --]

Just passing a string to mark_tsc_unstable() doesn't allow real code to change
based on the reason for the instablility. I changed mark_tsc_unstable()
to accept a string and a flag which denotes a general reason why the tsc
is unstable, and can be evaluated in code.

This is based off John Stultz patch to add the string reasons.

Signed-Off-By: Daniel Walker <dwalker@mvista.com>

---
arch/i386/kernel/cpu/cyrix.c | 9 ++++--
arch/i386/kernel/tsc.c | 39 +++++++++++++++++-----------
arch/x86_64/kernel/time.c | 3 +-
arch/x86_64/kernel/tsc.c | 28 +++++++++++++-------
arch/x86_64/kernel/tsc_sync.c | 3 +-
drivers/acpi/processor_idle.c | 6 ++--
include/asm-i386/mach-summit/mach_mpparse.h | 5 ++-
include/asm-i386/tsc.h | 13 ++++++++-
include/asm-x86_64/timex.h | 1
9 files changed, 73 insertions(+), 34 deletions(-)

Index: linux-2.6.21/arch/i386/kernel/cpu/cyrix.c
===================================================================
--- linux-2.6.21.orig/arch/i386/kernel/cpu/cyrix.c
+++ linux-2.6.21/arch/i386/kernel/cpu/cyrix.c
@@ -275,11 +275,14 @@ static void __cpuinit init_cyrix(struct
device = read_pci_config_16(0, 0, 0x12, PCI_DEVICE_ID);

/*
- * The 5510/5520 companion chips have a funky PIT.
+ * The 5510/5520 companion chips have a funky PIT
+ * and an unstable TSC.
*/
if (vendor == PCI_VENDOR_ID_CYRIX &&
- (device == PCI_DEVICE_ID_CYRIX_5510 || device == PCI_DEVICE_ID_CYRIX_5520))
- pit_latch_buggy = 1;
+ (device == PCI_DEVICE_ID_CYRIX_5510 ||
+ device == PCI_DEVICE_ID_CYRIX_5520))
+ mark_tsc_unstable(CLOCK_TSC_UNSTABLE_FREQUENCY,
+ "cyrix 5510/5520 detected");
}
#endif
c->x86_cache_size=16; /* Yep 16K integrated cache thats it */
Index: linux-2.6.21/arch/i386/kernel/tsc.c
===================================================================
--- linux-2.6.21.orig/arch/i386/kernel/tsc.c
+++ linux-2.6.21/arch/i386/kernel/tsc.c
@@ -233,7 +233,8 @@ time_cpufreq_notifier(struct notifier_bl
* TSC based sched_clock turns
* to junk w/ cpufreq
*/
- mark_tsc_unstable();
+ mark_tsc_unstable(CLOCK_TSC_CPUFREQ_ADJUSTED,
+ "cpufreq changes");
}
}
}
@@ -281,25 +282,34 @@ static struct clocksource clocksource_ts
CLOCK_SOURCE_MUST_VERIFY,
};

-void mark_tsc_unstable(void)
+void mark_tsc_unstable(enum tsc_unstable_flags flag, char *reason)
{
- if (!tsc_unstable) {
- tsc_unstable = 1;
- tsc_enabled = 0;
- /* Can be called before registration */
- if (clocksource_tsc.mult)
- clocksource_change_rating(&clocksource_tsc, 0);
- else
- clocksource_tsc.rating = 0;
+ if (likely(tsc_unstable))
+ return;
+
+ switch (flag) {
+ case CLOCK_TSC_UNSTABLE_FREQUENCY:
+ case CLOCK_TSC_HALTS_IN_CSTATES:
+
+ case CLOCK_TSC_UNSYNCHRONIZED:
+ case CLOCK_TSC_CPUFREQ_ADJUSTED:
+ 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(struct dmi_system_id *d)
{
- printk(KERN_NOTICE "%s detected: marking TSC unstable.\n",
- d->ident);
- tsc_unstable = 1;
+
+ mark_tsc_unstable(CLOCK_TSC_UNSTABLE_FREQUENCY, (char*)d->ident);
+
return 0;
}

@@ -331,7 +341,8 @@ __cpuinit int unsynchronized_tsc(void)
if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) {
/* assume multi socket systems are not synchronized: */
if (num_possible_cpus() > 1)
- tsc_unstable = 1;
+ mark_tsc_unstable(CLOCK_TSC_UNSYNCHRONIZED,
+ "Non-Intel SMP system");
}
return tsc_unstable;
}
Index: linux-2.6.21/arch/x86_64/kernel/time.c
===================================================================
--- linux-2.6.21.orig/arch/x86_64/kernel/time.c
+++ linux-2.6.21/arch/x86_64/kernel/time.c
@@ -348,7 +348,8 @@ void __init time_init(void)
}

if (unsynchronized_tsc())
- mark_tsc_unstable();
+ mark_tsc_unstable(CLOCK_TSC_UNSYNCHRONIZED,
+ "TSCs unsynchronized");

if (cpu_has(&boot_cpu_data, X86_FEATURE_RDTSCP))
vgetcpu_mode = VGETCPU_RDTSCP;
Index: linux-2.6.21/arch/x86_64/kernel/tsc.c
===================================================================
--- linux-2.6.21.orig/arch/x86_64/kernel/tsc.c
+++ linux-2.6.21/arch/x86_64/kernel/tsc.c
@@ -109,7 +109,8 @@ static int time_cpufreq_notifier(struct

cpu_khz = cpufreq_scale(cpu_khz_ref, ref_freq, freq->new);
if (!(freq->flags & CPUFREQ_CONST_LOOPS))
- mark_tsc_unstable();
+ mark_tsc_unstable(CLOCK_TSC_CPUFREQ_ADJUSTED,
+ "cpufreq changes");
}

set_cyc2ns_scale(cpu_khz_ref);
@@ -197,15 +198,24 @@ static struct clocksource clocksource_ts
.vread = vread_tsc,
};

-void mark_tsc_unstable(void)
+void mark_tsc_unstable(enum tsc_unstable_flags flag, char *reason)
{
- if (!tsc_unstable) {
- tsc_unstable = 1;
- /* Change only the rating, when not registered */
- if (clocksource_tsc.mult)
- clocksource_change_rating(&clocksource_tsc, 0);
- else
- clocksource_tsc.rating = 0;
+ if (likely(tsc_unstable))
+ return;
+
+ switch (flag) {
+ case CLOCK_TSC_UNSTABLE_FREQUENCY:
+ case CLOCK_TSC_HALTS_IN_CSTATES:
+
+ case CLOCK_TSC_UNSYNCHRONIZED:
+ case CLOCK_TSC_CPUFREQ_ADJUSTED:
+ tsc_unstable = 1;
+ 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);
Index: linux-2.6.21/arch/x86_64/kernel/tsc_sync.c
===================================================================
--- linux-2.6.21.orig/arch/x86_64/kernel/tsc_sync.c
+++ linux-2.6.21/arch/x86_64/kernel/tsc_sync.c
@@ -138,7 +138,8 @@ void __cpuinit check_tsc_sync_source(int
printk("\n");
printk(KERN_WARNING "Measured %Ld cycles TSC warp between CPUs,"
" turning off TSC clock.\n", max_warp);
- mark_tsc_unstable();
+ mark_tsc_unstable(CLOCK_TSC_UNSTABLE_FREQUENCY,
+ "check_tsc_sync_source failed");
nr_warps = 0;
max_warp = 0;
last_tsc = 0;
Index: linux-2.6.21/drivers/acpi/processor_idle.c
===================================================================
--- linux-2.6.21.orig/drivers/acpi/processor_idle.c
+++ linux-2.6.21/drivers/acpi/processor_idle.c
@@ -483,7 +483,8 @@ static void acpi_processor_idle(void)

#ifdef CONFIG_GENERIC_TIME
/* TSC halts in C2, so notify users */
- mark_tsc_unstable();
+ mark_tsc_unstable(CLOCK_TSC_HALTS_IN_CSTATES,
+ "possible TSC halt in C2");
#endif
/* Re-enable interrupts */
local_irq_enable();
@@ -525,7 +526,8 @@ static void acpi_processor_idle(void)

#ifdef CONFIG_GENERIC_TIME
/* TSC halts in C3, so notify users */
- mark_tsc_unstable();
+ mark_tsc_unstable(CLOCK_TSC_HALTS_IN_CSTATES,
+ "TSC halts in C3");
#endif
/* Re-enable interrupts */
local_irq_enable();
Index: linux-2.6.21/include/asm-i386/mach-summit/mach_mpparse.h
===================================================================
--- linux-2.6.21.orig/include/asm-i386/mach-summit/mach_mpparse.h
+++ linux-2.6.21/include/asm-i386/mach-summit/mach_mpparse.h
@@ -30,7 +30,8 @@ static inline int mps_oem_check(struct m
(!strncmp(productid, "VIGIL SMP", 9)
|| !strncmp(productid, "EXA", 3)
|| !strncmp(productid, "RUTHLESS SMP", 12))){
- mark_tsc_unstable();
+ mark_tsc_unstable(CLOCK_TSC_UNSYNCHRONIZED,
+ "Summit based system");
use_cyclone = 1; /*enable cyclone-timer*/
setup_summit();
return 1;
@@ -44,7 +45,7 @@ static inline int acpi_madt_oem_check(ch
if (!strncmp(oem_id, "IBM", 3) &&
(!strncmp(oem_table_id, "SERVIGIL", 8)
|| !strncmp(oem_table_id, "EXA", 3))){
- mark_tsc_unstable();
+ mark_tsc_unstable("Summit based system");
use_cyclone = 1; /*enable cyclone-timer*/
setup_summit();
return 1;
Index: linux-2.6.21/include/asm-i386/tsc.h
===================================================================
--- linux-2.6.21.orig/include/asm-i386/tsc.h
+++ linux-2.6.21/include/asm-i386/tsc.h
@@ -52,8 +52,19 @@ static __always_inline cycles_t get_cycl
return ret;
}

+/*
+ * These are the known reason why a TSC would be flaged
+ * as unstable.
+ */
+enum tsc_unstable_flags {
+ CLOCK_TSC_UNSTABLE_FREQUENCY = 0,
+ CLOCK_TSC_CPUFREQ_ADJUSTED,
+ CLOCK_TSC_UNSYNCHRONIZED,
+ CLOCK_TSC_HALTS_IN_CSTATES,
+};
+extern void mark_tsc_unstable(enum tsc_unstable_flags flag, char *reason);
+
extern void tsc_init(void);
-extern void mark_tsc_unstable(void);
extern int unsynchronized_tsc(void);
extern void init_tsc_clocksource(void);

Index: linux-2.6.21/include/asm-x86_64/timex.h
===================================================================
--- linux-2.6.21.orig/include/asm-x86_64/timex.h
+++ linux-2.6.21/include/asm-x86_64/timex.h
@@ -27,6 +27,5 @@ extern int read_current_timer(unsigned l
#define NS_SCALE 10 /* 2^10, carefully chosen */
#define US_SCALE 32 /* 2^32, arbitralrily chosen */

-extern void mark_tsc_unstable(void);
extern void set_cyc2ns_scale(unsigned long khz);
#endif

--