[lttng-modules.git] / wrapper / trace-clock.h

#ifndef _LTTNG_TRACE_CLOCK_H
#define _LTTNG_TRACE_CLOCK_H

/*
 * wrapper/trace-clock.h
 *
 * Contains LTTng trace clock mapping to LTTng trace clock or mainline monotonic
 * clock. This wrapper depends on CONFIG_HIGH_RES_TIMERS=y.
 *
 * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; only
 * version 2.1 of the License.
 *
 * This library 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. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#ifdef CONFIG_HAVE_TRACE_CLOCK
#include <linux/trace-clock.h>
#else /* CONFIG_HAVE_TRACE_CLOCK */

#include <linux/hardirq.h>
#include <linux/ktime.h>
#include <linux/time.h>
#include <linux/hrtimer.h>
#include <linux/version.h>
#include "random.h"

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0))
#error "Linux kernels 3.10 and 3.11 introduce a deadlock in the timekeeping subsystem. See http://lkml.kernel.org/r/1378943457-27314-1-git-send-email-john.stultz@linaro.org for details. Awaiting patch merge into Linux master, stable-3.10 and stable-3.11 for fine-grained kernel version blacklisting."
#endif

static inline u64 trace_clock_monotonic_wrapper(void)
{
	ktime_t ktime;

	/*
	 * Refuse to trace from NMIs with this wrapper, because an NMI could
	 * nest over the xtime write seqlock and deadlock.
	 */
	if (in_nmi())
		return (u64) -EIO;

	ktime = ktime_get();
	return ktime_to_ns(ktime);
}

static inline u32 trace_clock_read32(void)
{
	return (u32) trace_clock_monotonic_wrapper();
}

static inline u64 trace_clock_read64(void)
{
	return (u64) trace_clock_monotonic_wrapper();
}

static inline u64 trace_clock_freq(void)
{
	return (u64) NSEC_PER_SEC;
}

static inline int trace_clock_uuid(char *uuid)
{
	return wrapper_get_bootid(uuid);
}

static inline int get_trace_clock(void)
{
	/*
	 * LTTng: Using mainline kernel monotonic clock. NMIs will not be
	 * traced, and expect significant performance degradation compared to
	 * the LTTng trace clocks. Integration of the LTTng 0.x trace clocks
	 * into LTTng 2.0 is planned in a near future.
	 */
	printk(KERN_WARNING "LTTng: Using mainline kernel monotonic clock.\n");
	printk(KERN_WARNING "  * NMIs will not be traced,\n");
	printk(KERN_WARNING "  * expect significant performance degradation compared to the\n");
	printk(KERN_WARNING "    LTTng trace clocks.\n");
	printk(KERN_WARNING "Integration of the LTTng 0.x trace clocks into LTTng 2.0 is planned\n");
	printk(KERN_WARNING "in a near future.\n");

	return 0;
}

static inline void put_trace_clock(void)
{
}

#endif /* CONFIG_HAVE_TRACE_CLOCK */

#endif /* _LTTNG_TRACE_CLOCK_H */
Commit	Line	Data
886d51a3 MD	1	#ifndef _LTTNG_TRACE_CLOCK_H
	2	#define _LTTNG_TRACE_CLOCK_H
	3
f6c19f6e	4	/*
886d51a3	5	* wrapper/trace-clock.h
f6c19f6e MD	6	*
	7	* Contains LTTng trace clock mapping to LTTng trace clock or mainline monotonic
	8	* clock. This wrapper depends on CONFIG_HIGH_RES_TIMERS=y.
	9	*
886d51a3 MD	10	* Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	11	*
	12	* This library is free software; you can redistribute it and/or
	13	* modify it under the terms of the GNU Lesser General Public
	14	* License as published by the Free Software Foundation; only
	15	* version 2.1 of the License.
	16	*
	17	* This library is distributed in the hope that it will be useful,
	18	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	20	* Lesser General Public License for more details.
	21	*
	22	* You should have received a copy of the GNU Lesser General Public
	23	* License along with this library; if not, write to the Free Software
	24	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
f6c19f6e MD	25	*/
f6c19f6e MD	26
f6c19f6e MD	27	#ifdef CONFIG_HAVE_TRACE_CLOCK
	28	#include <linux/trace-clock.h>
	29	#else /* CONFIG_HAVE_TRACE_CLOCK */
	30
	31	#include <linux/hardirq.h>
	32	#include <linux/ktime.h>
	33	#include <linux/time.h>
	34	#include <linux/hrtimer.h>
00e96f51	35	#include <linux/version.h>
a82c63f1	36	#include "random.h"
f6c19f6e	37
00e96f51 MD	38	#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0))
	39	#error "Linux kernels 3.10 and 3.11 introduce a deadlock in the timekeeping subsystem. See http://lkml.kernel.org/r/1378943457-27314-1-git-send-email-john.stultz@linaro.org for details. Awaiting patch merge into Linux master, stable-3.10 and stable-3.11 for fine-grained kernel version blacklisting."
	40	#endif
	41
f6c19f6e MD	42	static inline u64 trace_clock_monotonic_wrapper(void)
	43	{
	44	ktime_t ktime;
	45
	46	/*
	47	* Refuse to trace from NMIs with this wrapper, because an NMI could
	48	* nest over the xtime write seqlock and deadlock.
	49	*/
	50	if (in_nmi())
97ca2c54	51	return (u64) -EIO;
f6c19f6e MD	52
f6c19f6e MD	53	ktime = ktime_get();
cfaf9f3d	54	return ktime_to_ns(ktime);
f6c19f6e MD	55	}
	56
	57	static inline u32 trace_clock_read32(void)
	58	{
	59	return (u32) trace_clock_monotonic_wrapper();
	60	}
	61
	62	static inline u64 trace_clock_read64(void)
	63	{
	64	return (u64) trace_clock_monotonic_wrapper();
	65	}
	66
a3ccff4f	67	static inline u64 trace_clock_freq(void)
f6c19f6e	68	{
a3ccff4f	69	return (u64) NSEC_PER_SEC;
f6c19f6e MD	70	}
f6c19f6e MD	71
a82c63f1	72	static inline int trace_clock_uuid(char *uuid)
f6c19f6e	73	{
a82c63f1	74	return wrapper_get_bootid(uuid);
f6c19f6e MD	75	}
	76
	77	static inline int get_trace_clock(void)
	78	{
22f8d33a MD	79	/*
	80	* LTTng: Using mainline kernel monotonic clock. NMIs will not be
	81	* traced, and expect significant performance degradation compared to
	82	* the LTTng trace clocks. Integration of the LTTng 0.x trace clocks
	83	* into LTTng 2.0 is planned in a near future.
	84	*/
f6c19f6e MD	85	printk(KERN_WARNING "LTTng: Using mainline kernel monotonic clock.\n");
	86	printk(KERN_WARNING " * NMIs will not be traced,\n");
	87	printk(KERN_WARNING " * expect significant performance degradation compared to the\n");
	88	printk(KERN_WARNING " LTTng trace clocks.\n");
cff67ebe MD	89	printk(KERN_WARNING "Integration of the LTTng 0.x trace clocks into LTTng 2.0 is planned\n");
cff67ebe MD	90	printk(KERN_WARNING "in a near future.\n");
f3bc08c5	91
f6c19f6e MD	92	return 0;
	93	}
	94
	95	static inline void put_trace_clock(void)
	96	{
	97	}
	98
	99	#endif /* CONFIG_HAVE_TRACE_CLOCK */
	100
a90917c3	101	#endif /* _LTTNG_TRACE_CLOCK_H */