time: Remove CONFIG_TIMER_STATS
Currently CONFIG_TIMER_STATS exposes process information across namespaces:
kernel/time/timer_list.c print_timer():
SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
/proc/timer_list:
#11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570
Given that the tracer can give the same information, this patch entirely
removes CONFIG_TIMER_STATS.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: linux-doc@vger.kernel.org
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Xing Gao <xgao01@email.wm.edu>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jessica Frazelle <me@jessfraz.com>
Cc: kernel-hardening@lists.openwall.com
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Michal Marek <mmarek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: http://lkml.kernel.org/r/20170208192659.GA32582@beast
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Kees Cook
Thomas Gleixner
parent
bb42ca4740
commit
dfb4357da6
@ -1,73 +0,0 @@
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timer_stats - timer usage statistics
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------------------------------------
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timer_stats is a debugging facility to make the timer (ab)usage in a Linux
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system visible to kernel and userspace developers. If enabled in the config
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but not used it has almost zero runtime overhead, and a relatively small
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data structure overhead. Even if collection is enabled runtime all the
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locking is per-CPU and lookup is hashed.
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timer_stats should be used by kernel and userspace developers to verify that
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their code does not make unduly use of timers. This helps to avoid unnecessary
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wakeups, which should be avoided to optimize power consumption.
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It can be enabled by CONFIG_TIMER_STATS in the "Kernel hacking" configuration
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section.
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timer_stats collects information about the timer events which are fired in a
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Linux system over a sample period:
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- the pid of the task(process) which initialized the timer
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- the name of the process which initialized the timer
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- the function where the timer was initialized
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- the callback function which is associated to the timer
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- the number of events (callbacks)
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timer_stats adds an entry to /proc: /proc/timer_stats
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This entry is used to control the statistics functionality and to read out the
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sampled information.
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The timer_stats functionality is inactive on bootup.
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To activate a sample period issue:
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# echo 1 >/proc/timer_stats
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To stop a sample period issue:
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# echo 0 >/proc/timer_stats
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The statistics can be retrieved by:
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# cat /proc/timer_stats
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While sampling is enabled, each readout from /proc/timer_stats will see
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newly updated statistics. Once sampling is disabled, the sampled information
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is kept until a new sample period is started. This allows multiple readouts.
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Sample output of /proc/timer_stats:
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Timerstats sample period: 3.888770 s
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12, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick)
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15, 1 swapper hcd_submit_urb (rh_timer_func)
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4, 959 kedac schedule_timeout (process_timeout)
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1, 0 swapper page_writeback_init (wb_timer_fn)
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28, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick)
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22, 2948 IRQ 4 tty_flip_buffer_push (delayed_work_timer_fn)
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3, 3100 bash schedule_timeout (process_timeout)
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1, 1 swapper queue_delayed_work_on (delayed_work_timer_fn)
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1, 1 swapper queue_delayed_work_on (delayed_work_timer_fn)
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1, 1 swapper neigh_table_init_no_netlink (neigh_periodic_timer)
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1, 2292 ip __netdev_watchdog_up (dev_watchdog)
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1, 23 events/1 do_cache_clean (delayed_work_timer_fn)
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90 total events, 30.0 events/sec
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The first column is the number of events, the second column the pid, the third
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column is the name of the process. The forth column shows the function which
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initialized the timer and in parenthesis the callback function which was
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executed on expiry.
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Thomas, Ingo
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Added flag to indicate 'deferrable timer' in /proc/timer_stats. A deferrable
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timer will appear as follows
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10D, 1 swapper queue_delayed_work_on (delayed_work_timer_fn)
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@ -88,12 +88,6 @@ enum hrtimer_restart {
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* @base: pointer to the timer base (per cpu and per clock)
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* @state: state information (See bit values above)
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* @is_rel: Set if the timer was armed relative
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* @start_pid: timer statistics field to store the pid of the task which
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* started the timer
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* @start_site: timer statistics field to store the site where the timer
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* was started
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* @start_comm: timer statistics field to store the name of the process which
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* started the timer
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*
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* The hrtimer structure must be initialized by hrtimer_init()
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*/
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@ -104,11 +98,6 @@ struct hrtimer {
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struct hrtimer_clock_base *base;
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u8 state;
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u8 is_rel;
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#ifdef CONFIG_TIMER_STATS
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int start_pid;
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void *start_site;
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char start_comm[16];
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#endif
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};
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/**
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@ -20,11 +20,6 @@ struct timer_list {
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unsigned long data;
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u32 flags;
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#ifdef CONFIG_TIMER_STATS
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int start_pid;
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void *start_site;
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char start_comm[16];
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#endif
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#ifdef CONFIG_LOCKDEP
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struct lockdep_map lockdep_map;
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#endif
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@ -197,46 +192,6 @@ extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
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*/
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#define NEXT_TIMER_MAX_DELTA ((1UL << 30) - 1)
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/*
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* Timer-statistics info:
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*/
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#ifdef CONFIG_TIMER_STATS
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extern int timer_stats_active;
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extern void init_timer_stats(void);
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extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
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void *timerf, char *comm, u32 flags);
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extern void __timer_stats_timer_set_start_info(struct timer_list *timer,
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void *addr);
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static inline void timer_stats_timer_set_start_info(struct timer_list *timer)
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{
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if (likely(!timer_stats_active))
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return;
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__timer_stats_timer_set_start_info(timer, __builtin_return_address(0));
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}
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static inline void timer_stats_timer_clear_start_info(struct timer_list *timer)
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{
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timer->start_site = NULL;
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}
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#else
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static inline void init_timer_stats(void)
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{
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}
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static inline void timer_stats_timer_set_start_info(struct timer_list *timer)
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{
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}
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static inline void timer_stats_timer_clear_start_info(struct timer_list *timer)
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{
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}
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#endif
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extern void add_timer(struct timer_list *timer);
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extern int try_to_del_timer_sync(struct timer_list *timer);
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@ -850,7 +850,6 @@ void __kthread_queue_delayed_work(struct kthread_worker *worker,
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list_add(&work->node, &worker->delayed_work_list);
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work->worker = worker;
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timer_stats_timer_set_start_info(&dwork->timer);
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timer->expires = jiffies + delay;
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add_timer(timer);
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}
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@ -15,6 +15,5 @@ ifeq ($(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST),y)
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endif
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obj-$(CONFIG_GENERIC_SCHED_CLOCK) += sched_clock.o
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obj-$(CONFIG_TICK_ONESHOT) += tick-oneshot.o tick-sched.o
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obj-$(CONFIG_TIMER_STATS) += timer_stats.o
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obj-$(CONFIG_DEBUG_FS) += timekeeping_debug.o
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obj-$(CONFIG_TEST_UDELAY) += test_udelay.o
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@ -766,34 +766,6 @@ void hrtimers_resume(void)
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clock_was_set_delayed();
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}
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static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
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{
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#ifdef CONFIG_TIMER_STATS
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if (timer->start_site)
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return;
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timer->start_site = __builtin_return_address(0);
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memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
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timer->start_pid = current->pid;
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#endif
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}
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static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
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{
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#ifdef CONFIG_TIMER_STATS
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timer->start_site = NULL;
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#endif
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}
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static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
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{
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#ifdef CONFIG_TIMER_STATS
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if (likely(!timer_stats_active))
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return;
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timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
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timer->function, timer->start_comm, 0);
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#endif
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}
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/*
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* Counterpart to lock_hrtimer_base above:
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*/
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@ -932,7 +904,6 @@ remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool rest
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* rare case and less expensive than a smp call.
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*/
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debug_deactivate(timer);
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timer_stats_hrtimer_clear_start_info(timer);
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reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
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if (!restart)
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@ -990,8 +961,6 @@ void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
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/* Switch the timer base, if necessary: */
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new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
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timer_stats_hrtimer_set_start_info(timer);
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leftmost = enqueue_hrtimer(timer, new_base);
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if (!leftmost)
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goto unlock;
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@ -1128,12 +1097,6 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
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base = hrtimer_clockid_to_base(clock_id);
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timer->base = &cpu_base->clock_base[base];
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timerqueue_init(&timer->node);
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#ifdef CONFIG_TIMER_STATS
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timer->start_site = NULL;
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timer->start_pid = -1;
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memset(timer->start_comm, 0, TASK_COMM_LEN);
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#endif
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}
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/**
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@ -1217,7 +1180,6 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
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raw_write_seqcount_barrier(&cpu_base->seq);
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__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
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timer_stats_account_hrtimer(timer);
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fn = timer->function;
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/*
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@ -571,38 +571,6 @@ internal_add_timer(struct timer_base *base, struct timer_list *timer)
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trigger_dyntick_cpu(base, timer);
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}
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#ifdef CONFIG_TIMER_STATS
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void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
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{
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if (timer->start_site)
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return;
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timer->start_site = addr;
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memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
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timer->start_pid = current->pid;
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}
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static void timer_stats_account_timer(struct timer_list *timer)
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{
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void *site;
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/*
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* start_site can be concurrently reset by
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* timer_stats_timer_clear_start_info()
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*/
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site = READ_ONCE(timer->start_site);
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if (likely(!site))
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return;
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timer_stats_update_stats(timer, timer->start_pid, site,
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timer->function, timer->start_comm,
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timer->flags);
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}
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#else
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static void timer_stats_account_timer(struct timer_list *timer) {}
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#endif
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#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
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static struct debug_obj_descr timer_debug_descr;
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@ -789,11 +757,6 @@ static void do_init_timer(struct timer_list *timer, unsigned int flags,
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{
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timer->entry.pprev = NULL;
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timer->flags = flags | raw_smp_processor_id();
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#ifdef CONFIG_TIMER_STATS
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timer->start_site = NULL;
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timer->start_pid = -1;
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memset(timer->start_comm, 0, TASK_COMM_LEN);
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#endif
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lockdep_init_map(&timer->lockdep_map, name, key, 0);
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}
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@ -1001,8 +964,6 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
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base = lock_timer_base(timer, &flags);
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}
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timer_stats_timer_set_start_info(timer);
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ret = detach_if_pending(timer, base, false);
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if (!ret && pending_only)
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goto out_unlock;
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@ -1130,7 +1091,6 @@ void add_timer_on(struct timer_list *timer, int cpu)
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struct timer_base *new_base, *base;
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unsigned long flags;
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timer_stats_timer_set_start_info(timer);
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BUG_ON(timer_pending(timer) || !timer->function);
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new_base = get_timer_cpu_base(timer->flags, cpu);
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@ -1176,7 +1136,6 @@ int del_timer(struct timer_list *timer)
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debug_assert_init(timer);
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timer_stats_timer_clear_start_info(timer);
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if (timer_pending(timer)) {
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base = lock_timer_base(timer, &flags);
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ret = detach_if_pending(timer, base, true);
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@ -1204,10 +1163,9 @@ int try_to_del_timer_sync(struct timer_list *timer)
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base = lock_timer_base(timer, &flags);
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if (base->running_timer != timer) {
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timer_stats_timer_clear_start_info(timer);
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if (base->running_timer != timer)
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ret = detach_if_pending(timer, base, true);
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}
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spin_unlock_irqrestore(&base->lock, flags);
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return ret;
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@ -1331,7 +1289,6 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
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unsigned long data;
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timer = hlist_entry(head->first, struct timer_list, entry);
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timer_stats_account_timer(timer);
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base->running_timer = timer;
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detach_timer(timer, true);
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@ -1868,7 +1825,6 @@ static void __init init_timer_cpus(void)
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void __init init_timers(void)
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{
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init_timer_cpus();
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init_timer_stats();
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open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
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}
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@ -62,21 +62,11 @@ static void
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print_timer(struct seq_file *m, struct hrtimer *taddr, struct hrtimer *timer,
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int idx, u64 now)
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{
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#ifdef CONFIG_TIMER_STATS
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char tmp[TASK_COMM_LEN + 1];
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#endif
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SEQ_printf(m, " #%d: ", idx);
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print_name_offset(m, taddr);
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SEQ_printf(m, ", ");
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print_name_offset(m, timer->function);
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SEQ_printf(m, ", S:%02x", timer->state);
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#ifdef CONFIG_TIMER_STATS
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SEQ_printf(m, ", ");
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print_name_offset(m, timer->start_site);
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memcpy(tmp, timer->start_comm, TASK_COMM_LEN);
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tmp[TASK_COMM_LEN] = 0;
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SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
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#endif
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SEQ_printf(m, "\n");
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SEQ_printf(m, " # expires at %Lu-%Lu nsecs [in %Ld to %Ld nsecs]\n",
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(unsigned long long)ktime_to_ns(hrtimer_get_softexpires(timer)),
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@ -1,425 +0,0 @@
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/*
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* kernel/time/timer_stats.c
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*
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* Collect timer usage statistics.
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*
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* Copyright(C) 2006, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
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*
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* timer_stats is based on timer_top, a similar functionality which was part of
|
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* Con Kolivas dyntick patch set. It was developed by Daniel Petrini at the
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* Instituto Nokia de Tecnologia - INdT - Manaus. timer_top's design was based
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* on dynamic allocation of the statistics entries and linear search based
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* lookup combined with a global lock, rather than the static array, hash
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* and per-CPU locking which is used by timer_stats. It was written for the
|
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* pre hrtimer kernel code and therefore did not take hrtimers into account.
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* Nevertheless it provided the base for the timer_stats implementation and
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* was a helpful source of inspiration. Kudos to Daniel and the Nokia folks
|
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* for this effort.
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*
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* timer_top.c is
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* Copyright (C) 2005 Instituto Nokia de Tecnologia - INdT - Manaus
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* Written by Daniel Petrini <d.pensator@gmail.com>
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* timer_top.c was released under the GNU General Public License version 2
|
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*
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* We export the addresses and counting of timer functions being called,
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* the pid and cmdline from the owner process if applicable.
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*
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* Start/stop data collection:
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* # echo [1|0] >/proc/timer_stats
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*
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* Display the information collected so far:
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* # cat /proc/timer_stats
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*
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* This program is free software; you can redistribute it and/or modify
|
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* it under the terms of the GNU General Public License version 2 as
|
||||
* published by the Free Software Foundation.
|
||||
*/
|
||||
|
||||
#include <linux/proc_fs.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/spinlock.h>
|
||||
#include <linux/sched.h>
|
||||
#include <linux/seq_file.h>
|
||||
#include <linux/kallsyms.h>
|
||||
|
||||
#include <linux/uaccess.h>
|
||||
|
||||
/*
|
||||
* This is our basic unit of interest: a timer expiry event identified
|
||||
* by the timer, its start/expire functions and the PID of the task that
|
||||
* started the timer. We count the number of times an event happens:
|
||||
*/
|
||||
struct entry {
|
||||
/*
|
||||
* Hash list:
|
||||
*/
|
||||
struct entry *next;
|
||||
|
||||
/*
|
||||
* Hash keys:
|
||||
*/
|
||||
void *timer;
|
||||
void *start_func;
|
||||
void *expire_func;
|
||||
pid_t pid;
|
||||
|
||||
/*
|
||||
* Number of timeout events:
|
||||
*/
|
||||
unsigned long count;
|
||||
u32 flags;
|
||||
|
||||
/*
|
||||
* We save the command-line string to preserve
|
||||
* this information past task exit:
|
||||
*/
|
||||
char comm[TASK_COMM_LEN + 1];
|
||||
|
||||
} ____cacheline_aligned_in_smp;
|
||||
|
||||
/*
|
||||
* Spinlock protecting the tables - not taken during lookup:
|
||||
*/
|
||||
static DEFINE_RAW_SPINLOCK(table_lock);
|
||||
|
||||
/*
|
||||
* Per-CPU lookup locks for fast hash lookup:
|
||||
*/
|
||||
static DEFINE_PER_CPU(raw_spinlock_t, tstats_lookup_lock);
|
||||
|
||||
/*
|
||||
* Mutex to serialize state changes with show-stats activities:
|
||||
*/
|
||||
static DEFINE_MUTEX(show_mutex);
|
||||
|
||||
/*
|
||||
* Collection status, active/inactive:
|
||||
*/
|
||||
int __read_mostly timer_stats_active;
|
||||
|
||||
/*
|
||||
* Beginning/end timestamps of measurement:
|
||||
*/
|
||||
static ktime_t time_start, time_stop;
|
||||
|
||||
/*
|
||||
* tstat entry structs only get allocated while collection is
|
||||
* active and never freed during that time - this simplifies
|
||||
* things quite a bit.
|
||||
*
|
||||
* They get freed when a new collection period is started.
|
||||
*/
|
||||
#define MAX_ENTRIES_BITS 10
|
||||
#define MAX_ENTRIES (1UL << MAX_ENTRIES_BITS)
|
||||
|
||||
static unsigned long nr_entries;
|
||||
static struct entry entries[MAX_ENTRIES];
|
||||
|
||||
static atomic_t overflow_count;
|
||||
|
||||
/*
|
||||
* The entries are in a hash-table, for fast lookup:
|
||||
*/
|
||||
#define TSTAT_HASH_BITS (MAX_ENTRIES_BITS - 1)
|
||||
#define TSTAT_HASH_SIZE (1UL << TSTAT_HASH_BITS)
|
||||
#define TSTAT_HASH_MASK (TSTAT_HASH_SIZE - 1)
|
||||
|
||||
#define __tstat_hashfn(entry) \
|
||||
(((unsigned long)(entry)->timer ^ \
|
||||
(unsigned long)(entry)->start_func ^ \
|
||||
(unsigned long)(entry)->expire_func ^ \
|
||||
(unsigned long)(entry)->pid ) & TSTAT_HASH_MASK)
|
||||
|
||||
#define tstat_hashentry(entry) (tstat_hash_table + __tstat_hashfn(entry))
|
||||
|
||||
static struct entry *tstat_hash_table[TSTAT_HASH_SIZE] __read_mostly;
|
||||
|
||||
static void reset_entries(void)
|
||||
{
|
||||
nr_entries = 0;
|
||||
memset(entries, 0, sizeof(entries));
|
||||
memset(tstat_hash_table, 0, sizeof(tstat_hash_table));
|
||||
atomic_set(&overflow_count, 0);
|
||||
}
|
||||
|
||||
static struct entry *alloc_entry(void)
|
||||
{
|
||||
if (nr_entries >= MAX_ENTRIES)
|
||||
return NULL;
|
||||
|
||||
return entries + nr_entries++;
|
||||
}
|
||||
|
||||
static int match_entries(struct entry *entry1, struct entry *entry2)
|
||||
{
|
||||
return entry1->timer == entry2->timer &&
|
||||
entry1->start_func == entry2->start_func &&
|
||||
entry1->expire_func == entry2->expire_func &&
|
||||
entry1->pid == entry2->pid;
|
||||
}
|
||||
|
||||
/*
|
||||
* Look up whether an entry matching this item is present
|
||||
* in the hash already. Must be called with irqs off and the
|
||||
* lookup lock held:
|
||||
*/
|
||||
static struct entry *tstat_lookup(struct entry *entry, char *comm)
|
||||
{
|
||||
struct entry **head, *curr, *prev;
|
||||
|
||||
head = tstat_hashentry(entry);
|
||||
curr = *head;
|
||||
|
||||
/*
|
||||
* The fastpath is when the entry is already hashed,
|
||||
* we do this with the lookup lock held, but with the
|
||||
* table lock not held:
|
||||
*/
|
||||
while (curr) {
|
||||
if (match_entries(curr, entry))
|
||||
return curr;
|
||||
|
||||
curr = curr->next;
|
||||
}
|
||||
/*
|
||||
* Slowpath: allocate, set up and link a new hash entry:
|
||||
*/
|
||||
prev = NULL;
|
||||
curr = *head;
|
||||
|
||||
raw_spin_lock(&table_lock);
|
||||
/*
|
||||
* Make sure we have not raced with another CPU:
|
||||
*/
|
||||
while (curr) {
|
||||
if (match_entries(curr, entry))
|
||||
goto out_unlock;
|
||||
|
||||
prev = curr;
|
||||
curr = curr->next;
|
||||
}
|
||||
|
||||
curr = alloc_entry();
|
||||
if (curr) {
|
||||
*curr = *entry;
|
||||
curr->count = 0;
|
||||
curr->next = NULL;
|
||||
memcpy(curr->comm, comm, TASK_COMM_LEN);
|
||||
|
||||
smp_mb(); /* Ensure that curr is initialized before insert */
|
||||
|
||||
if (prev)
|
||||
prev->next = curr;
|
||||
else
|
||||
*head = curr;
|
||||
}
|
||||
out_unlock:
|
||||
raw_spin_unlock(&table_lock);
|
||||
|
||||
return curr;
|
||||
}
|
||||
|
||||
/**
|
||||
* timer_stats_update_stats - Update the statistics for a timer.
|
||||
* @timer: pointer to either a timer_list or a hrtimer
|
||||
* @pid: the pid of the task which set up the timer
|
||||
* @startf: pointer to the function which did the timer setup
|
||||
* @timerf: pointer to the timer callback function of the timer
|
||||
* @comm: name of the process which set up the timer
|
||||
* @tflags: The flags field of the timer
|
||||
*
|
||||
* When the timer is already registered, then the event counter is
|
||||
* incremented. Otherwise the timer is registered in a free slot.
|
||||
*/
|
||||
void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
|
||||
void *timerf, char *comm, u32 tflags)
|
||||
{
|
||||
/*
|
||||
* It doesn't matter which lock we take:
|
||||
*/
|
||||
raw_spinlock_t *lock;
|
||||
struct entry *entry, input;
|
||||
unsigned long flags;
|
||||
|
||||
if (likely(!timer_stats_active))
|
||||
return;
|
||||
|
||||
lock = &per_cpu(tstats_lookup_lock, raw_smp_processor_id());
|
||||
|
||||
input.timer = timer;
|
||||
input.start_func = startf;
|
||||
input.expire_func = timerf;
|
||||
input.pid = pid;
|
||||
input.flags = tflags;
|
||||
|
||||
raw_spin_lock_irqsave(lock, flags);
|
||||
if (!timer_stats_active)
|
||||
goto out_unlock;
|
||||
|
||||
entry = tstat_lookup(&input, comm);
|
||||
if (likely(entry))
|
||||
entry->count++;
|
||||
else
|
||||
atomic_inc(&overflow_count);
|
||||
|
||||
out_unlock:
|
||||
raw_spin_unlock_irqrestore(lock, flags);
|
||||
}
|
||||
|
||||
static void print_name_offset(struct seq_file *m, unsigned long addr)
|
||||
{
|
||||
char symname[KSYM_NAME_LEN];
|
||||
|
||||
if (lookup_symbol_name(addr, symname) < 0)
|
||||
seq_printf(m, "<%p>", (void *)addr);
|
||||
else
|
||||
seq_printf(m, "%s", symname);
|
||||
}
|
||||
|
||||
static int tstats_show(struct seq_file *m, void *v)
|
||||
{
|
||||
struct timespec64 period;
|
||||
struct entry *entry;
|
||||
unsigned long ms;
|
||||
long events = 0;
|
||||
ktime_t time;
|
||||
int i;
|
||||
|
||||
mutex_lock(&show_mutex);
|
||||
/*
|
||||
* If still active then calculate up to now:
|
||||
*/
|
||||
if (timer_stats_active)
|
||||
time_stop = ktime_get();
|
||||
|
||||
time = ktime_sub(time_stop, time_start);
|
||||
|
||||
period = ktime_to_timespec64(time);
|
||||
ms = period.tv_nsec / 1000000;
|
||||
|
||||
seq_puts(m, "Timer Stats Version: v0.3\n");
|
||||
seq_printf(m, "Sample period: %ld.%03ld s\n", (long)period.tv_sec, ms);
|
||||
if (atomic_read(&overflow_count))
|
||||
seq_printf(m, "Overflow: %d entries\n", atomic_read(&overflow_count));
|
||||
seq_printf(m, "Collection: %s\n", timer_stats_active ? "active" : "inactive");
|
||||
|
||||
for (i = 0; i < nr_entries; i++) {
|
||||
entry = entries + i;
|
||||
if (entry->flags & TIMER_DEFERRABLE) {
|
||||
seq_printf(m, "%4luD, %5d %-16s ",
|
||||
entry->count, entry->pid, entry->comm);
|
||||
} else {
|
||||
seq_printf(m, " %4lu, %5d %-16s ",
|
||||
entry->count, entry->pid, entry->comm);
|
||||
}
|
||||
|
||||
print_name_offset(m, (unsigned long)entry->start_func);
|
||||
seq_puts(m, " (");
|
||||
print_name_offset(m, (unsigned long)entry->expire_func);
|
||||
seq_puts(m, ")\n");
|
||||
|
||||
events += entry->count;
|
||||
}
|
||||
|
||||
ms += period.tv_sec * 1000;
|
||||
if (!ms)
|
||||
ms = 1;
|
||||
|
||||
if (events && period.tv_sec)
|
||||
seq_printf(m, "%ld total events, %ld.%03ld events/sec\n",
|
||||
events, events * 1000 / ms,
|
||||
(events * 1000000 / ms) % 1000);
|
||||
else
|
||||
seq_printf(m, "%ld total events\n", events);
|
||||
|
||||
mutex_unlock(&show_mutex);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* After a state change, make sure all concurrent lookup/update
|
||||
* activities have stopped:
|
||||
*/
|
||||
static void sync_access(void)
|
||||
{
|
||||
unsigned long flags;
|
||||
int cpu;
|
||||
|
||||
for_each_online_cpu(cpu) {
|
||||
raw_spinlock_t *lock = &per_cpu(tstats_lookup_lock, cpu);
|
||||
|
||||
raw_spin_lock_irqsave(lock, flags);
|
||||
/* nothing */
|
||||
raw_spin_unlock_irqrestore(lock, flags);
|
||||
}
|
||||
}
|
||||
|
||||
static ssize_t tstats_write(struct file *file, const char __user *buf,
|
||||
size_t count, loff_t *offs)
|
||||
{
|
||||
char ctl[2];
|
||||
|
||||
if (count != 2 || *offs)
|
||||
return -EINVAL;
|
||||
|
||||
if (copy_from_user(ctl, buf, count))
|
||||
return -EFAULT;
|
||||
|
||||
mutex_lock(&show_mutex);
|
||||
switch (ctl[0]) {
|
||||
case '0':
|
||||
if (timer_stats_active) {
|
||||
timer_stats_active = 0;
|
||||
time_stop = ktime_get();
|
||||
sync_access();
|
||||
}
|
||||
break;
|
||||
case '1':
|
||||
if (!timer_stats_active) {
|
||||
reset_entries();
|
||||
time_start = ktime_get();
|
||||
smp_mb();
|
||||
timer_stats_active = 1;
|
||||
}
|
||||
break;
|
||||
default:
|
||||
count = -EINVAL;
|
||||
}
|
||||
mutex_unlock(&show_mutex);
|
||||
|
||||
return count;
|
||||
}
|
||||
|
||||
static int tstats_open(struct inode *inode, struct file *filp)
|
||||
{
|
||||
return single_open(filp, tstats_show, NULL);
|
||||
}
|
||||
|
||||
static const struct file_operations tstats_fops = {
|
||||
.open = tstats_open,
|
||||
.read = seq_read,
|
||||
.write = tstats_write,
|
||||
.llseek = seq_lseek,
|
||||
.release = single_release,
|
||||
};
|
||||
|
||||
void __init init_timer_stats(void)
|
||||
{
|
||||
int cpu;
|
||||
|
||||
for_each_possible_cpu(cpu)
|
||||
raw_spin_lock_init(&per_cpu(tstats_lookup_lock, cpu));
|
||||
}
|
||||
|
||||
static int __init init_tstats_procfs(void)
|
||||
{
|
||||
struct proc_dir_entry *pe;
|
||||
|
||||
pe = proc_create("timer_stats", 0644, NULL, &tstats_fops);
|
||||
if (!pe)
|
||||
return -ENOMEM;
|
||||
return 0;
|
||||
}
|
||||
__initcall(init_tstats_procfs);
|
||||
@ -1523,8 +1523,6 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
|
||||
return;
|
||||
}
|
||||
|
||||
timer_stats_timer_set_start_info(&dwork->timer);
|
||||
|
||||
dwork->wq = wq;
|
||||
dwork->cpu = cpu;
|
||||
timer->expires = jiffies + delay;
|
||||
|
||||
@ -980,20 +980,6 @@ config DEBUG_TIMEKEEPING
|
||||
|
||||
If unsure, say N.
|
||||
|
||||
config TIMER_STATS
|
||||
bool "Collect kernel timers statistics"
|
||||
depends on DEBUG_KERNEL && PROC_FS
|
||||
help
|
||||
If you say Y here, additional code will be inserted into the
|
||||
timer routines to collect statistics about kernel timers being
|
||||
reprogrammed. The statistics can be read from /proc/timer_stats.
|
||||
The statistics collection is started by writing 1 to /proc/timer_stats,
|
||||
writing 0 stops it. This feature is useful to collect information
|
||||
about timer usage patterns in kernel and userspace. This feature
|
||||
is lightweight if enabled in the kernel config but not activated
|
||||
(it defaults to deactivated on bootup and will only be activated
|
||||
if some application like powertop activates it explicitly).
|
||||
|
||||
config DEBUG_PREEMPT
|
||||
bool "Debug preemptible kernel"
|
||||
depends on DEBUG_KERNEL && PREEMPT && TRACE_IRQFLAGS_SUPPORT
|
||||
|
||||
Loading…
Reference in New Issue
Block a user