Re: [PATCH v2 1/4] Add generic correlated clocksource code and ART to TSC conversion code
On 08/07/2015 04:01 PM, Christopher Hall wrote:
Original patch description:
Subject: ptp: Get sync timestamps
From: Thomas Gleixner
Date: Wed, 29 Jul 2015 10:52:06 +0200
The ART stuff wants to be splitted out.
Changes ===
Add struct correlated_cs (clocksource) with pointer to original clocksource
and function pointer to convert correlated clocksource to the original
Add struct correlated_ts (timestamp) with function pointer to read correlated
clocksource, device and system (in terms of correlated clocksource)
counter values (input) with resulting converted real and monotonic raw
system times (output)
Add get_correlated_timestamp() function which given specific correlated_cs
and correlated_ts convert correlated counter value to system time
Add art_to_tsc conversion function translated Always Running Timer (ART) to
TSC value
---
arch/x86/kernel/tsc.c | 31 ++
include/linux/clocksource.h | 30 +
include/linux/timekeeping.h | 4 +++
kernel/time/timekeeping.c | 63 +
4 files changed, 128 insertions(+)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7437b41..a90aa6a 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1059,6 +1059,27 @@ int unsynchronized_tsc(void)
return 0;
}
+static u32 tsc_numerator;
+static u32 tsc_denominator;
+/*
+ * CHECKME: Do we need the adjust value? It should be 0, but if we run
+ * in a VM this might be a different story.
+ */
+static u64 tsc_adjust;
+
+static u64 art_to_tsc(u64 cycles)
+{
+ u64 tmp, res = tsc_adjust;
+
+ res += (cycles / tsc_denominator) * tsc_numerator;
+ tmp = (cycles % tsc_denominator) * tsc_numerator;
+ res += tmp / tsc_denominator;
+ return res;
Nice trick!
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 278dd27..2ed3d0c 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -258,4 +258,34 @@ void acpi_generic_timer_init(void);
static inline void acpi_generic_timer_init(void) { }
#endif
+/**
+ * struct correlated_cs - Descriptor for a clocksource correlated to another
clocksource
+ * @related_cs:Pointer to the related timekeeping clocksource
+ * @convert: Conversion function to convert a timestamp from
+ * the correlated clocksource to cycles of the related
+ * timekeeping clocksource
+ */
+struct correlated_cs {
+ struct clocksource *related_cs;
+ u64 (*convert)(u64 cycles);
Should the name make it clearer which way it converts? For example,
convert_to_related? We might also want convert_from_related.
--Andy
--
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[PATCH v2 1/4] Add generic correlated clocksource code and ART to TSC conversion code
Original patch description:
Subject: ptp: Get sync timestamps
From: Thomas Gleixner
Date: Wed, 29 Jul 2015 10:52:06 +0200
The ART stuff wants to be splitted out.
Changes ===
Add struct correlated_cs (clocksource) with pointer to original clocksource
and function pointer to convert correlated clocksource to the original
Add struct correlated_ts (timestamp) with function pointer to read correlated
clocksource, device and system (in terms of correlated clocksource)
counter values (input) with resulting converted real and monotonic raw
system times (output)
Add get_correlated_timestamp() function which given specific correlated_cs
and correlated_ts convert correlated counter value to system time
Add art_to_tsc conversion function translated Always Running Timer (ART) to
TSC value
---
arch/x86/kernel/tsc.c | 31 ++
include/linux/clocksource.h | 30 +
include/linux/timekeeping.h | 4 +++
kernel/time/timekeeping.c | 63 +
4 files changed, 128 insertions(+)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7437b41..a90aa6a 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1059,6 +1059,27 @@ int unsynchronized_tsc(void)
return 0;
}
+static u32 tsc_numerator;
+static u32 tsc_denominator;
+/*
+ * CHECKME: Do we need the adjust value? It should be 0, but if we run
+ * in a VM this might be a different story.
+ */
+static u64 tsc_adjust;
+
+static u64 art_to_tsc(u64 cycles)
+{
+ u64 tmp, res = tsc_adjust;
+
+ res += (cycles / tsc_denominator) * tsc_numerator;
+ tmp = (cycles % tsc_denominator) * tsc_numerator;
+ res += tmp / tsc_denominator;
+ return res;
+}
+
+struct correlated_cs art_timestamper = {
+ .convert= art_to_tsc,
+};
static void tsc_refine_calibration_work(struct work_struct *work);
static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
@@ -1129,6 +1150,16 @@ static void tsc_refine_calibration_work(struct
work_struct *work)
(unsigned long)tsc_khz / 1000,
(unsigned long)tsc_khz % 1000);
+ /*
+* TODO:
+*
+* If the system has ART, initialize the art_to_tsc conversion
+* and set: art_timestamp.related_cs = _clocksource.
+*
+* Before that point a call to get_correlated_timestamp will
+* fail the clocksource match check.
+*/
+
out:
clocksource_register_khz(_tsc, tsc_khz);
}
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 278dd27..2ed3d0c 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -258,4 +258,34 @@ void acpi_generic_timer_init(void);
static inline void acpi_generic_timer_init(void) { }
#endif
+/**
+ * struct correlated_cs - Descriptor for a clocksource correlated to another
clocksource
+ * @related_cs:Pointer to the related timekeeping clocksource
+ * @convert: Conversion function to convert a timestamp from
+ * the correlated clocksource to cycles of the related
+ * timekeeping clocksource
+ */
+struct correlated_cs {
+ struct clocksource *related_cs;
+ u64 (*convert)(u64 cycles);
+};
+
+struct correlated_ts;
+
+/**
+ * struct correlated_ts - Descriptor for taking a correlated time stamp
+ * @get_ts:Function to read out a synced system and device
+ * timestamp
+ * @system_ts: The raw system clock timestamp
+ * @device_ts: The raw device timestamp
+ * @system_real: @system_ts converted to CLOCK_REALTIME
+ * @system_raw:@system_ts converted to CLOCK_MONOTONIC_RAW
+ */
+struct correlated_ts {
+ int (*get_ts)(struct correlated_ts *ts);
+ u64 system_ts;
+ u64 device_ts;
+ u64 system_real;
+ u64 system_raw;
+};
#endif /* _LINUX_CLOCKSOURCE_H */
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 6e191e4..a9e1a2d 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -258,6 +258,10 @@ extern void timekeeping_inject_sleeptime64(struct
timespec64 *delta);
*/
extern void getnstime_raw_and_real(struct timespec *ts_raw,
struct timespec *ts_real);
+struct correlated_ts;
+struct correlated_cs;
+extern int get_correlated_timestamp(struct correlated_ts *crt,
+ struct correlated_cs *crs);
/*
* Persistent clock related interfaces
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index bca3667..769a04b 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -312,6 +312,19 @@ static inline s64 timekeeping_get_ns(struct
Re: [PATCH v2 1/4] Add generic correlated clocksource code and ART to TSC conversion code
On 08/07/2015 04:01 PM, Christopher Hall wrote:
Original patch description:
Subject: ptp: Get sync timestamps
From: Thomas Gleixner t...@linutronix.de
Date: Wed, 29 Jul 2015 10:52:06 +0200
The ART stuff wants to be splitted out.
Changes ===
Add struct correlated_cs (clocksource) with pointer to original clocksource
and function pointer to convert correlated clocksource to the original
Add struct correlated_ts (timestamp) with function pointer to read correlated
clocksource, device and system (in terms of correlated clocksource)
counter values (input) with resulting converted real and monotonic raw
system times (output)
Add get_correlated_timestamp() function which given specific correlated_cs
and correlated_ts convert correlated counter value to system time
Add art_to_tsc conversion function translated Always Running Timer (ART) to
TSC value
---
arch/x86/kernel/tsc.c | 31 ++
include/linux/clocksource.h | 30 +
include/linux/timekeeping.h | 4 +++
kernel/time/timekeeping.c | 63 +
4 files changed, 128 insertions(+)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7437b41..a90aa6a 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1059,6 +1059,27 @@ int unsynchronized_tsc(void)
return 0;
}
+static u32 tsc_numerator;
+static u32 tsc_denominator;
+/*
+ * CHECKME: Do we need the adjust value? It should be 0, but if we run
+ * in a VM this might be a different story.
+ */
+static u64 tsc_adjust;
+
+static u64 art_to_tsc(u64 cycles)
+{
+ u64 tmp, res = tsc_adjust;
+
+ res += (cycles / tsc_denominator) * tsc_numerator;
+ tmp = (cycles % tsc_denominator) * tsc_numerator;
+ res += tmp / tsc_denominator;
+ return res;
Nice trick!
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 278dd27..2ed3d0c 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -258,4 +258,34 @@ void acpi_generic_timer_init(void);
static inline void acpi_generic_timer_init(void) { }
#endif
+/**
+ * struct correlated_cs - Descriptor for a clocksource correlated to another
clocksource
+ * @related_cs:Pointer to the related timekeeping clocksource
+ * @convert: Conversion function to convert a timestamp from
+ * the correlated clocksource to cycles of the related
+ * timekeeping clocksource
+ */
+struct correlated_cs {
+ struct clocksource *related_cs;
+ u64 (*convert)(u64 cycles);
Should the name make it clearer which way it converts? For example,
convert_to_related? We might also want convert_from_related.
--Andy
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2 1/4] Add generic correlated clocksource code and ART to TSC conversion code
Original patch description:
Subject: ptp: Get sync timestamps
From: Thomas Gleixner t...@linutronix.de
Date: Wed, 29 Jul 2015 10:52:06 +0200
The ART stuff wants to be splitted out.
Changes ===
Add struct correlated_cs (clocksource) with pointer to original clocksource
and function pointer to convert correlated clocksource to the original
Add struct correlated_ts (timestamp) with function pointer to read correlated
clocksource, device and system (in terms of correlated clocksource)
counter values (input) with resulting converted real and monotonic raw
system times (output)
Add get_correlated_timestamp() function which given specific correlated_cs
and correlated_ts convert correlated counter value to system time
Add art_to_tsc conversion function translated Always Running Timer (ART) to
TSC value
---
arch/x86/kernel/tsc.c | 31 ++
include/linux/clocksource.h | 30 +
include/linux/timekeeping.h | 4 +++
kernel/time/timekeeping.c | 63 +
4 files changed, 128 insertions(+)
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7437b41..a90aa6a 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1059,6 +1059,27 @@ int unsynchronized_tsc(void)
return 0;
}
+static u32 tsc_numerator;
+static u32 tsc_denominator;
+/*
+ * CHECKME: Do we need the adjust value? It should be 0, but if we run
+ * in a VM this might be a different story.
+ */
+static u64 tsc_adjust;
+
+static u64 art_to_tsc(u64 cycles)
+{
+ u64 tmp, res = tsc_adjust;
+
+ res += (cycles / tsc_denominator) * tsc_numerator;
+ tmp = (cycles % tsc_denominator) * tsc_numerator;
+ res += tmp / tsc_denominator;
+ return res;
+}
+
+struct correlated_cs art_timestamper = {
+ .convert= art_to_tsc,
+};
static void tsc_refine_calibration_work(struct work_struct *work);
static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
@@ -1129,6 +1150,16 @@ static void tsc_refine_calibration_work(struct
work_struct *work)
(unsigned long)tsc_khz / 1000,
(unsigned long)tsc_khz % 1000);
+ /*
+* TODO:
+*
+* If the system has ART, initialize the art_to_tsc conversion
+* and set: art_timestamp.related_cs = tsc_clocksource.
+*
+* Before that point a call to get_correlated_timestamp will
+* fail the clocksource match check.
+*/
+
out:
clocksource_register_khz(clocksource_tsc, tsc_khz);
}
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 278dd27..2ed3d0c 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -258,4 +258,34 @@ void acpi_generic_timer_init(void);
static inline void acpi_generic_timer_init(void) { }
#endif
+/**
+ * struct correlated_cs - Descriptor for a clocksource correlated to another
clocksource
+ * @related_cs:Pointer to the related timekeeping clocksource
+ * @convert: Conversion function to convert a timestamp from
+ * the correlated clocksource to cycles of the related
+ * timekeeping clocksource
+ */
+struct correlated_cs {
+ struct clocksource *related_cs;
+ u64 (*convert)(u64 cycles);
+};
+
+struct correlated_ts;
+
+/**
+ * struct correlated_ts - Descriptor for taking a correlated time stamp
+ * @get_ts:Function to read out a synced system and device
+ * timestamp
+ * @system_ts: The raw system clock timestamp
+ * @device_ts: The raw device timestamp
+ * @system_real: @system_ts converted to CLOCK_REALTIME
+ * @system_raw:@system_ts converted to CLOCK_MONOTONIC_RAW
+ */
+struct correlated_ts {
+ int (*get_ts)(struct correlated_ts *ts);
+ u64 system_ts;
+ u64 device_ts;
+ u64 system_real;
+ u64 system_raw;
+};
#endif /* _LINUX_CLOCKSOURCE_H */
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h
index 6e191e4..a9e1a2d 100644
--- a/include/linux/timekeeping.h
+++ b/include/linux/timekeeping.h
@@ -258,6 +258,10 @@ extern void timekeeping_inject_sleeptime64(struct
timespec64 *delta);
*/
extern void getnstime_raw_and_real(struct timespec *ts_raw,
struct timespec *ts_real);
+struct correlated_ts;
+struct correlated_cs;
+extern int get_correlated_timestamp(struct correlated_ts *crt,
+ struct correlated_cs *crs);
/*
* Persistent clock related interfaces
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index bca3667..769a04b 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -312,6 +312,19 @@ static inline s64
