2005-04-16 16:20:36 -06:00
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#ifndef _LINUX_TIME_H
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#define _LINUX_TIME_H
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#include <linux/types.h>
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#ifdef __KERNEL__
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2007-07-21 05:37:37 -06:00
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# include <linux/cache.h>
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2006-01-09 21:52:26 -07:00
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# include <linux/seqlock.h>
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2008-06-12 02:47:56 -06:00
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# include <linux/math64.h>
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2005-04-16 16:20:36 -06:00
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#endif
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#ifndef _STRUCT_TIMESPEC
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#define _STRUCT_TIMESPEC
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struct timespec {
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make exported headers use strict posix types
A number of standard posix types are used in exported headers, which
is not allowed if __STRICT_KERNEL_NAMES is defined. In order to
get rid of the non-__STRICT_KERNEL_NAMES part and to make sane headers
the default, we have to change them all to safe types.
There are also still some leftovers in reiserfs_fs.h, elfcore.h
and coda.h, but these files have not compiled in user space for
a long time.
This leaves out the various integer types ({u_,u,}int{8,16,32,64}_t),
which we take care of separately.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Cc: netdev@vger.kernel.org
Cc: linux-ppp@vger.kernel.org
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-25 16:51:39 -07:00
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__kernel_time_t tv_sec; /* seconds */
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long tv_nsec; /* nanoseconds */
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2005-04-16 16:20:36 -06:00
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};
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2006-01-09 21:52:26 -07:00
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#endif
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2005-04-16 16:20:36 -06:00
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struct timeval {
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make exported headers use strict posix types
A number of standard posix types are used in exported headers, which
is not allowed if __STRICT_KERNEL_NAMES is defined. In order to
get rid of the non-__STRICT_KERNEL_NAMES part and to make sane headers
the default, we have to change them all to safe types.
There are also still some leftovers in reiserfs_fs.h, elfcore.h
and coda.h, but these files have not compiled in user space for
a long time.
This leaves out the various integer types ({u_,u,}int{8,16,32,64}_t),
which we take care of separately.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Cc: netdev@vger.kernel.org
Cc: linux-ppp@vger.kernel.org
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-25 16:51:39 -07:00
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__kernel_time_t tv_sec; /* seconds */
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__kernel_suseconds_t tv_usec; /* microseconds */
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2005-04-16 16:20:36 -06:00
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};
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struct timezone {
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int tz_minuteswest; /* minutes west of Greenwich */
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int tz_dsttime; /* type of dst correction */
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};
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#ifdef __KERNEL__
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2008-10-15 23:02:06 -06:00
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extern struct timezone sys_tz;
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2006-01-09 21:52:26 -07:00
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/* Parameters used to convert the timespec values: */
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2006-06-26 05:58:20 -06:00
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#define MSEC_PER_SEC 1000L
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#define USEC_PER_MSEC 1000L
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#define NSEC_PER_USEC 1000L
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#define NSEC_PER_MSEC 1000000L
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#define USEC_PER_SEC 1000000L
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#define NSEC_PER_SEC 1000000000L
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2010-08-09 15:20:10 -06:00
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#define FSEC_PER_SEC 1000000000000000LL
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2005-04-16 16:20:36 -06:00
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2008-08-31 09:09:53 -06:00
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#define TIME_T_MAX (time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)
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2007-07-17 05:03:53 -06:00
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static inline int timespec_equal(const struct timespec *a,
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const struct timespec *b)
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2006-01-09 21:52:26 -07:00
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{
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2005-04-16 16:20:36 -06:00
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return (a->tv_sec == b->tv_sec) && (a->tv_nsec == b->tv_nsec);
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2006-01-09 21:52:26 -07:00
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}
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2005-04-16 16:20:36 -06:00
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2006-02-11 18:55:52 -07:00
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/*
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* lhs < rhs: return <0
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* lhs == rhs: return 0
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* lhs > rhs: return >0
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*/
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2007-02-10 02:45:49 -07:00
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static inline int timespec_compare(const struct timespec *lhs, const struct timespec *rhs)
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2006-02-11 18:55:52 -07:00
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{
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if (lhs->tv_sec < rhs->tv_sec)
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return -1;
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if (lhs->tv_sec > rhs->tv_sec)
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return 1;
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return lhs->tv_nsec - rhs->tv_nsec;
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}
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2007-02-10 02:45:49 -07:00
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static inline int timeval_compare(const struct timeval *lhs, const struct timeval *rhs)
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2006-02-11 18:55:52 -07:00
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{
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if (lhs->tv_sec < rhs->tv_sec)
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return -1;
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if (lhs->tv_sec > rhs->tv_sec)
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return 1;
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return lhs->tv_usec - rhs->tv_usec;
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}
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2006-01-09 21:52:23 -07:00
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extern unsigned long mktime(const unsigned int year, const unsigned int mon,
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const unsigned int day, const unsigned int hour,
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const unsigned int min, const unsigned int sec);
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2009-09-14 15:37:40 -06:00
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extern void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec);
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2010-07-13 18:56:19 -06:00
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/*
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* timespec_add_safe assumes both values are positive and checks
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* for overflow. It will return TIME_T_MAX if the reutrn would be
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* smaller then either of the arguments.
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*/
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2008-08-31 09:09:53 -06:00
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extern struct timespec timespec_add_safe(const struct timespec lhs,
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const struct timespec rhs);
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2005-04-16 16:20:36 -06:00
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2010-07-13 18:56:19 -06:00
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static inline struct timespec timespec_add(struct timespec lhs,
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struct timespec rhs)
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{
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struct timespec ts_delta;
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set_normalized_timespec(&ts_delta, lhs.tv_sec + rhs.tv_sec,
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lhs.tv_nsec + rhs.tv_nsec);
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return ts_delta;
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}
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2006-07-14 01:24:36 -06:00
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/*
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* sub = lhs - rhs, in normalized form
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*/
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static inline struct timespec timespec_sub(struct timespec lhs,
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struct timespec rhs)
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{
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struct timespec ts_delta;
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set_normalized_timespec(&ts_delta, lhs.tv_sec - rhs.tv_sec,
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lhs.tv_nsec - rhs.tv_nsec);
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return ts_delta;
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}
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2006-01-09 21:52:29 -07:00
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/*
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* Returns true if the timespec is norm, false if denorm:
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*/
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#define timespec_valid(ts) \
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2006-01-31 20:10:23 -07:00
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(((ts)->tv_sec >= 0) && (((unsigned long) (ts)->tv_nsec) < NSEC_PER_SEC))
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2006-01-09 21:52:29 -07:00
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2007-10-17 00:27:16 -06:00
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extern seqlock_t xtime_lock;
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2005-04-16 16:20:36 -06:00
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2009-08-14 07:47:31 -06:00
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extern void read_persistent_clock(struct timespec *ts);
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2009-08-14 07:47:32 -06:00
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extern void read_boot_clock(struct timespec *ts);
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2007-07-21 05:37:37 -06:00
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extern int update_persistent_clock(struct timespec now);
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extern int no_sync_cmos_clock __read_mostly;
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2006-06-26 01:25:06 -06:00
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void timekeeping_init(void);
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2008-12-22 15:05:28 -07:00
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extern int timekeeping_suspended;
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2006-06-26 01:25:06 -06:00
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2007-07-24 19:38:34 -06:00
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unsigned long get_seconds(void);
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2005-04-16 16:20:36 -06:00
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struct timespec current_kernel_time(void);
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2010-07-13 18:56:25 -06:00
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struct timespec __current_kernel_time(void); /* does not take xtime_lock */
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struct timespec __get_wall_to_monotonic(void); /* does not take xtime_lock */
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2009-08-19 20:13:34 -06:00
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struct timespec get_monotonic_coarse(void);
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2005-04-16 16:20:36 -06:00
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2006-01-09 21:52:26 -07:00
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#define CURRENT_TIME (current_kernel_time())
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2007-07-24 18:47:43 -06:00
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#define CURRENT_TIME_SEC ((struct timespec) { get_seconds(), 0 })
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2005-04-16 16:20:36 -06:00
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2009-05-01 14:10:26 -06:00
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/* Some architectures do not supply their own clocksource.
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* This is mainly the case in architectures that get their
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* inter-tick times by reading the counter on their interval
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* timer. Since these timers wrap every tick, they're not really
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* useful as clocksources. Wrapping them to act like one is possible
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* but not very efficient. So we provide a callout these arches
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* can implement for use with the jiffies clocksource to provide
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* finer then tick granular time.
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*/
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#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
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extern u32 arch_gettimeoffset(void);
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#else
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static inline u32 arch_gettimeoffset(void) { return 0; }
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#endif
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2005-04-16 16:20:36 -06:00
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extern void do_gettimeofday(struct timeval *tv);
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extern int do_settimeofday(struct timespec *tv);
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extern int do_sys_settimeofday(struct timespec *tv, struct timezone *tz);
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2006-01-09 21:52:38 -07:00
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#define do_posix_clock_monotonic_gettime(ts) ktime_get_ts(ts)
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utimensat implementation
Implement utimensat(2) which is an extension to futimesat(2) in that it
a) supports nano-second resolution for the timestamps
b) allows to selectively ignore the atime/mtime value
c) allows to selectively use the current time for either atime or mtime
d) supports changing the atime/mtime of a symlink itself along the lines
of the BSD lutimes(3) functions
For this change the internally used do_utimes() functions was changed to
accept a timespec time value and an additional flags parameter.
Additionally the sys_utime function was changed to match compat_sys_utime
which already use do_utimes instead of duplicating the work.
Also, the completely missing futimensat() functionality is added. We have
such a function in glibc but we have to resort to using /proc/self/fd/* which
not everybody likes (chroot etc).
Test application (the syscall number will need per-arch editing):
#include <errno.h>
#include <fcntl.h>
#include <time.h>
#include <sys/time.h>
#include <stddef.h>
#include <syscall.h>
#define __NR_utimensat 280
#define UTIME_NOW ((1l << 30) - 1l)
#define UTIME_OMIT ((1l << 30) - 2l)
int
main(void)
{
int status = 0;
int fd = open("ttt", O_RDWR|O_CREAT|O_EXCL, 0666);
if (fd == -1)
error (1, errno, "failed to create test file \"ttt\"");
struct stat64 st1;
if (fstat64 (fd, &st1) != 0)
error (1, errno, "fstat failed");
struct timespec t[2];
t[0].tv_sec = 0;
t[0].tv_nsec = 0;
t[1].tv_sec = 0;
t[1].tv_nsec = 0;
if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
error (1, errno, "utimensat failed");
struct stat64 st2;
if (fstat64 (fd, &st2) != 0)
error (1, errno, "fstat failed");
if (st2.st_atim.tv_sec != 0 || st2.st_atim.tv_nsec != 0)
{
puts ("atim not reset to zero");
status = 1;
}
if (st2.st_mtim.tv_sec != 0 || st2.st_mtim.tv_nsec != 0)
{
puts ("mtim not reset to zero");
status = 1;
}
if (status != 0)
goto out;
t[0] = st1.st_atim;
t[1].tv_sec = 0;
t[1].tv_nsec = UTIME_OMIT;
if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
error (1, errno, "utimensat failed");
if (fstat64 (fd, &st2) != 0)
error (1, errno, "fstat failed");
if (st2.st_atim.tv_sec != st1.st_atim.tv_sec
|| st2.st_atim.tv_nsec != st1.st_atim.tv_nsec)
{
puts ("atim not set");
status = 1;
}
if (st2.st_mtim.tv_sec != 0 || st2.st_mtim.tv_nsec != 0)
{
puts ("mtim changed from zero");
status = 1;
}
if (status != 0)
goto out;
t[0].tv_sec = 0;
t[0].tv_nsec = UTIME_OMIT;
t[1] = st1.st_mtim;
if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
error (1, errno, "utimensat failed");
if (fstat64 (fd, &st2) != 0)
error (1, errno, "fstat failed");
if (st2.st_atim.tv_sec != st1.st_atim.tv_sec
|| st2.st_atim.tv_nsec != st1.st_atim.tv_nsec)
{
puts ("mtim changed from original time");
status = 1;
}
if (st2.st_mtim.tv_sec != st1.st_mtim.tv_sec
|| st2.st_mtim.tv_nsec != st1.st_mtim.tv_nsec)
{
puts ("mtim not set");
status = 1;
}
if (status != 0)
goto out;
sleep (2);
t[0].tv_sec = 0;
t[0].tv_nsec = UTIME_NOW;
t[1].tv_sec = 0;
t[1].tv_nsec = UTIME_NOW;
if (syscall(__NR_utimensat, AT_FDCWD, "ttt", t, 0) != 0)
error (1, errno, "utimensat failed");
if (fstat64 (fd, &st2) != 0)
error (1, errno, "fstat failed");
struct timeval tv;
gettimeofday(&tv,NULL);
if (st2.st_atim.tv_sec <= st1.st_atim.tv_sec
|| st2.st_atim.tv_sec > tv.tv_sec)
{
puts ("atim not set to NOW");
status = 1;
}
if (st2.st_mtim.tv_sec <= st1.st_mtim.tv_sec
|| st2.st_mtim.tv_sec > tv.tv_sec)
{
puts ("mtim not set to NOW");
status = 1;
}
if (symlink ("ttt", "tttsym") != 0)
error (1, errno, "cannot create symlink");
t[0].tv_sec = 0;
t[0].tv_nsec = 0;
t[1].tv_sec = 0;
t[1].tv_nsec = 0;
if (syscall(__NR_utimensat, AT_FDCWD, "tttsym", t, AT_SYMLINK_NOFOLLOW) != 0)
error (1, errno, "utimensat failed");
if (lstat64 ("tttsym", &st2) != 0)
error (1, errno, "lstat failed");
if (st2.st_atim.tv_sec != 0 || st2.st_atim.tv_nsec != 0)
{
puts ("symlink atim not reset to zero");
status = 1;
}
if (st2.st_mtim.tv_sec != 0 || st2.st_mtim.tv_nsec != 0)
{
puts ("symlink mtim not reset to zero");
status = 1;
}
if (status != 0)
goto out;
t[0].tv_sec = 1;
t[0].tv_nsec = 0;
t[1].tv_sec = 1;
t[1].tv_nsec = 0;
if (syscall(__NR_utimensat, fd, NULL, t, 0) != 0)
error (1, errno, "utimensat failed");
if (fstat64 (fd, &st2) != 0)
error (1, errno, "fstat failed");
if (st2.st_atim.tv_sec != 1 || st2.st_atim.tv_nsec != 0)
{
puts ("atim not reset to one");
status = 1;
}
if (st2.st_mtim.tv_sec != 1 || st2.st_mtim.tv_nsec != 0)
{
puts ("mtim not reset to one");
status = 1;
}
if (status == 0)
puts ("all OK");
out:
close (fd);
unlink ("ttt");
unlink ("tttsym");
return status;
}
[akpm@linux-foundation.org: add missing i386 syscall table entry]
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Cc: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 01:33:25 -06:00
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extern long do_utimes(int dfd, char __user *filename, struct timespec *times, int flags);
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2005-04-16 16:20:36 -06:00
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struct itimerval;
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2006-01-09 21:52:26 -07:00
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extern int do_setitimer(int which, struct itimerval *value,
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struct itimerval *ovalue);
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2006-03-25 04:06:33 -07:00
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extern unsigned int alarm_setitimer(unsigned int seconds);
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2005-04-16 16:20:36 -06:00
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extern int do_getitimer(int which, struct itimerval *value);
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2006-01-09 21:52:26 -07:00
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extern void getnstimeofday(struct timespec *tv);
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2008-08-20 17:37:30 -06:00
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extern void getrawmonotonic(struct timespec *ts);
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2007-07-16 00:39:41 -06:00
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extern void getboottime(struct timespec *ts);
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extern void monotonic_to_bootbased(struct timespec *ts);
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2005-04-16 16:20:36 -06:00
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extern struct timespec timespec_trunc(struct timespec t, unsigned gran);
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2008-02-08 05:19:24 -07:00
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extern int timekeeping_valid_for_hres(void);
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2009-08-18 11:45:10 -06:00
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extern u64 timekeeping_max_deferment(void);
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2007-05-08 01:27:59 -06:00
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extern void update_wall_time(void);
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2009-08-14 07:47:18 -06:00
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extern void timekeeping_leap_insert(int leapsecond);
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2005-04-16 16:20:36 -06:00
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timers: fix itimer/many thread hang
Overview
This patch reworks the handling of POSIX CPU timers, including the
ITIMER_PROF, ITIMER_VIRT timers and rlimit handling. It was put together
with the help of Roland McGrath, the owner and original writer of this code.
The problem we ran into, and the reason for this rework, has to do with using
a profiling timer in a process with a large number of threads. It appears
that the performance of the old implementation of run_posix_cpu_timers() was
at least O(n*3) (where "n" is the number of threads in a process) or worse.
Everything is fine with an increasing number of threads until the time taken
for that routine to run becomes the same as or greater than the tick time, at
which point things degrade rather quickly.
This patch fixes bug 9906, "Weird hang with NPTL and SIGPROF."
Code Changes
This rework corrects the implementation of run_posix_cpu_timers() to make it
run in constant time for a particular machine. (Performance may vary between
one machine and another depending upon whether the kernel is built as single-
or multiprocessor and, in the latter case, depending upon the number of
running processors.) To do this, at each tick we now update fields in
signal_struct as well as task_struct. The run_posix_cpu_timers() function
uses those fields to make its decisions.
We define a new structure, "task_cputime," to contain user, system and
scheduler times and use these in appropriate places:
struct task_cputime {
cputime_t utime;
cputime_t stime;
unsigned long long sum_exec_runtime;
};
This is included in the structure "thread_group_cputime," which is a new
substructure of signal_struct and which varies for uniprocessor versus
multiprocessor kernels. For uniprocessor kernels, it uses "task_cputime" as
a simple substructure, while for multiprocessor kernels it is a pointer:
struct thread_group_cputime {
struct task_cputime totals;
};
struct thread_group_cputime {
struct task_cputime *totals;
};
We also add a new task_cputime substructure directly to signal_struct, to
cache the earliest expiration of process-wide timers, and task_cputime also
replaces the it_*_expires fields of task_struct (used for earliest expiration
of thread timers). The "thread_group_cputime" structure contains process-wide
timers that are updated via account_user_time() and friends. In the non-SMP
case the structure is a simple aggregator; unfortunately in the SMP case that
simplicity was not achievable due to cache-line contention between CPUs (in
one measured case performance was actually _worse_ on a 16-cpu system than
the same test on a 4-cpu system, due to this contention). For SMP, the
thread_group_cputime counters are maintained as a per-cpu structure allocated
using alloc_percpu(). The timer functions update only the timer field in
the structure corresponding to the running CPU, obtained using per_cpu_ptr().
We define a set of inline functions in sched.h that we use to maintain the
thread_group_cputime structure and hide the differences between UP and SMP
implementations from the rest of the kernel. The thread_group_cputime_init()
function initializes the thread_group_cputime structure for the given task.
The thread_group_cputime_alloc() is a no-op for UP; for SMP it calls the
out-of-line function thread_group_cputime_alloc_smp() to allocate and fill
in the per-cpu structures and fields. The thread_group_cputime_free()
function, also a no-op for UP, in SMP frees the per-cpu structures. The
thread_group_cputime_clone_thread() function (also a UP no-op) for SMP calls
thread_group_cputime_alloc() if the per-cpu structures haven't yet been
allocated. The thread_group_cputime() function fills the task_cputime
structure it is passed with the contents of the thread_group_cputime fields;
in UP it's that simple but in SMP it must also safely check that tsk->signal
is non-NULL (if it is it just uses the appropriate fields of task_struct) and,
if so, sums the per-cpu values for each online CPU. Finally, the three
functions account_group_user_time(), account_group_system_time() and
account_group_exec_runtime() are used by timer functions to update the
respective fields of the thread_group_cputime structure.
Non-SMP operation is trivial and will not be mentioned further.
The per-cpu structure is always allocated when a task creates its first new
thread, via a call to thread_group_cputime_clone_thread() from copy_signal().
It is freed at process exit via a call to thread_group_cputime_free() from
cleanup_signal().
All functions that formerly summed utime/stime/sum_sched_runtime values from
from all threads in the thread group now use thread_group_cputime() to
snapshot the values in the thread_group_cputime structure or the values in
the task structure itself if the per-cpu structure hasn't been allocated.
Finally, the code in kernel/posix-cpu-timers.c has changed quite a bit.
The run_posix_cpu_timers() function has been split into a fast path and a
slow path; the former safely checks whether there are any expired thread
timers and, if not, just returns, while the slow path does the heavy lifting.
With the dedicated thread group fields, timers are no longer "rebalanced" and
the process_timer_rebalance() function and related code has gone away. All
summing loops are gone and all code that used them now uses the
thread_group_cputime() inline. When process-wide timers are set, the new
task_cputime structure in signal_struct is used to cache the earliest
expiration; this is checked in the fast path.
Performance
The fix appears not to add significant overhead to existing operations. It
generally performs the same as the current code except in two cases, one in
which it performs slightly worse (Case 5 below) and one in which it performs
very significantly better (Case 2 below). Overall it's a wash except in those
two cases.
I've since done somewhat more involved testing on a dual-core Opteron system.
Case 1: With no itimer running, for a test with 100,000 threads, the fixed
kernel took 1428.5 seconds, 513 seconds more than the unfixed system,
all of which was spent in the system. There were twice as many
voluntary context switches with the fix as without it.
Case 2: With an itimer running at .01 second ticks and 4000 threads (the most
an unmodified kernel can handle), the fixed kernel ran the test in
eight percent of the time (5.8 seconds as opposed to 70 seconds) and
had better tick accuracy (.012 seconds per tick as opposed to .023
seconds per tick).
Case 3: A 4000-thread test with an initial timer tick of .01 second and an
interval of 10,000 seconds (i.e. a timer that ticks only once) had
very nearly the same performance in both cases: 6.3 seconds elapsed
for the fixed kernel versus 5.5 seconds for the unfixed kernel.
With fewer threads (eight in these tests), the Case 1 test ran in essentially
the same time on both the modified and unmodified kernels (5.2 seconds versus
5.8 seconds). The Case 2 test ran in about the same time as well, 5.9 seconds
versus 5.4 seconds but again with much better tick accuracy, .013 seconds per
tick versus .025 seconds per tick for the unmodified kernel.
Since the fix affected the rlimit code, I also tested soft and hard CPU limits.
Case 4: With a hard CPU limit of 20 seconds and eight threads (and an itimer
running), the modified kernel was very slightly favored in that while
it killed the process in 19.997 seconds of CPU time (5.002 seconds of
wall time), only .003 seconds of that was system time, the rest was
user time. The unmodified kernel killed the process in 20.001 seconds
of CPU (5.014 seconds of wall time) of which .016 seconds was system
time. Really, though, the results were too close to call. The results
were essentially the same with no itimer running.
Case 5: With a soft limit of 20 seconds and a hard limit of 2000 seconds
(where the hard limit would never be reached) and an itimer running,
the modified kernel exhibited worse tick accuracy than the unmodified
kernel: .050 seconds/tick versus .028 seconds/tick. Otherwise,
performance was almost indistinguishable. With no itimer running this
test exhibited virtually identical behavior and times in both cases.
In times past I did some limited performance testing. those results are below.
On a four-cpu Opteron system without this fix, a sixteen-thread test executed
in 3569.991 seconds, of which user was 3568.435s and system was 1.556s. On
the same system with the fix, user and elapsed time were about the same, but
system time dropped to 0.007 seconds. Performance with eight, four and one
thread were comparable. Interestingly, the timer ticks with the fix seemed
more accurate: The sixteen-thread test with the fix received 149543 ticks
for 0.024 seconds per tick, while the same test without the fix received 58720
for 0.061 seconds per tick. Both cases were configured for an interval of
0.01 seconds. Again, the other tests were comparable. Each thread in this
test computed the primes up to 25,000,000.
I also did a test with a large number of threads, 100,000 threads, which is
impossible without the fix. In this case each thread computed the primes only
up to 10,000 (to make the runtime manageable). System time dominated, at
1546.968 seconds out of a total 2176.906 seconds (giving a user time of
629.938s). It received 147651 ticks for 0.015 seconds per tick, still quite
accurate. There is obviously no comparable test without the fix.
Signed-off-by: Frank Mayhar <fmayhar@google.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-12 10:54:39 -06:00
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struct tms;
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extern void do_sys_times(struct tms *);
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2009-09-23 16:56:10 -06:00
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/*
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* Similar to the struct tm in userspace <time.h>, but it needs to be here so
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* that the kernel source is self contained.
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*/
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struct tm {
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/*
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* the number of seconds after the minute, normally in the range
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* 0 to 59, but can be up to 60 to allow for leap seconds
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*/
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int tm_sec;
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/* the number of minutes after the hour, in the range 0 to 59*/
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int tm_min;
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/* the number of hours past midnight, in the range 0 to 23 */
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int tm_hour;
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/* the day of the month, in the range 1 to 31 */
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int tm_mday;
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/* the number of months since January, in the range 0 to 11 */
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int tm_mon;
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/* the number of years since 1900 */
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long tm_year;
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/* the number of days since Sunday, in the range 0 to 6 */
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int tm_wday;
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/* the number of days since January 1, in the range 0 to 365 */
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int tm_yday;
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};
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void time_to_tm(time_t totalsecs, int offset, struct tm *result);
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2006-01-09 21:52:30 -07:00
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/**
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* timespec_to_ns - Convert timespec to nanoseconds
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* @ts: pointer to the timespec variable to be converted
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*
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* Returns the scalar nanosecond representation of the timespec
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* parameter.
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*/
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2006-03-26 02:38:11 -07:00
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static inline s64 timespec_to_ns(const struct timespec *ts)
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2006-01-09 21:52:30 -07:00
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{
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2006-03-26 02:38:11 -07:00
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return ((s64) ts->tv_sec * NSEC_PER_SEC) + ts->tv_nsec;
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2006-01-09 21:52:30 -07:00
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}
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/**
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* timeval_to_ns - Convert timeval to nanoseconds
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* @ts: pointer to the timeval variable to be converted
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*
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* Returns the scalar nanosecond representation of the timeval
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* parameter.
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*/
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2006-03-26 02:38:11 -07:00
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static inline s64 timeval_to_ns(const struct timeval *tv)
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2006-01-09 21:52:30 -07:00
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{
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2006-03-26 02:38:11 -07:00
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return ((s64) tv->tv_sec * NSEC_PER_SEC) +
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2006-01-09 21:52:30 -07:00
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tv->tv_usec * NSEC_PER_USEC;
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}
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/**
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* ns_to_timespec - Convert nanoseconds to timespec
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* @nsec: the nanoseconds value to be converted
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*
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* Returns the timespec representation of the nsec parameter.
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*/
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2006-03-26 02:38:11 -07:00
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extern struct timespec ns_to_timespec(const s64 nsec);
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2006-01-09 21:52:30 -07:00
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/**
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* ns_to_timeval - Convert nanoseconds to timeval
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* @nsec: the nanoseconds value to be converted
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*
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* Returns the timeval representation of the nsec parameter.
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*/
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2006-03-26 02:38:11 -07:00
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extern struct timeval ns_to_timeval(const s64 nsec);
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2006-01-09 21:52:30 -07:00
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2006-06-26 01:25:08 -06:00
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/**
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* timespec_add_ns - Adds nanoseconds to a timespec
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* @a: pointer to timespec to be incremented
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* @ns: unsigned nanoseconds value to be added
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2008-06-12 02:48:00 -06:00
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*
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* This must always be inlined because its used from the x86-64 vdso,
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* which cannot call other kernel functions.
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2006-06-26 01:25:08 -06:00
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*/
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2008-06-12 02:48:00 -06:00
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static __always_inline void timespec_add_ns(struct timespec *a, u64 ns)
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2006-06-26 01:25:08 -06:00
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{
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2008-06-12 02:48:00 -06:00
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a->tv_sec += __iter_div_u64_rem(a->tv_nsec + ns, NSEC_PER_SEC, &ns);
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2006-06-26 01:25:08 -06:00
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a->tv_nsec = ns;
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}
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2005-04-16 16:20:36 -06:00
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#endif /* __KERNEL__ */
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#define NFDBITS __NFDBITS
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#define FD_SETSIZE __FD_SETSIZE
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#define FD_SET(fd,fdsetp) __FD_SET(fd,fdsetp)
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#define FD_CLR(fd,fdsetp) __FD_CLR(fd,fdsetp)
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#define FD_ISSET(fd,fdsetp) __FD_ISSET(fd,fdsetp)
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#define FD_ZERO(fdsetp) __FD_ZERO(fdsetp)
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/*
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* Names of the interval timers, and structure
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2006-01-09 21:52:26 -07:00
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* defining a timer setting:
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2005-04-16 16:20:36 -06:00
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*/
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2006-01-09 21:52:26 -07:00
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#define ITIMER_REAL 0
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#define ITIMER_VIRTUAL 1
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#define ITIMER_PROF 2
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2005-04-16 16:20:36 -06:00
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2006-01-09 21:52:26 -07:00
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struct itimerspec {
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struct timespec it_interval; /* timer period */
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struct timespec it_value; /* timer expiration */
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2005-04-16 16:20:36 -06:00
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};
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2006-01-09 21:52:26 -07:00
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struct itimerval {
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struct timeval it_interval; /* timer interval */
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struct timeval it_value; /* current value */
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2005-04-16 16:20:36 -06:00
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};
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/*
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2006-01-09 21:52:26 -07:00
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* The IDs of the various system clocks (for POSIX.1b interval timers):
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2005-04-16 16:20:36 -06:00
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*/
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2006-01-09 21:52:25 -07:00
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#define CLOCK_REALTIME 0
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#define CLOCK_MONOTONIC 1
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#define CLOCK_PROCESS_CPUTIME_ID 2
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#define CLOCK_THREAD_CPUTIME_ID 3
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2008-08-20 17:37:30 -06:00
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#define CLOCK_MONOTONIC_RAW 4
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2009-08-19 20:13:34 -06:00
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#define CLOCK_REALTIME_COARSE 5
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#define CLOCK_MONOTONIC_COARSE 6
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2005-04-16 16:20:36 -06:00
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/*
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2006-01-09 21:52:26 -07:00
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* The IDs of various hardware clocks:
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2005-04-16 16:20:36 -06:00
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*/
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2006-01-09 21:52:25 -07:00
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#define CLOCK_SGI_CYCLE 10
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#define MAX_CLOCKS 16
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#define CLOCKS_MASK (CLOCK_REALTIME | CLOCK_MONOTONIC)
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#define CLOCKS_MONO CLOCK_MONOTONIC
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2005-04-16 16:20:36 -06:00
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/*
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2006-01-09 21:52:26 -07:00
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* The various flags for setting POSIX.1b interval timers:
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2005-04-16 16:20:36 -06:00
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*/
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2006-01-09 21:52:25 -07:00
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#define TIMER_ABSTIME 0x01
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2005-04-16 16:20:36 -06:00
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#endif
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