summaryrefslogtreecommitdiffstats
path: root/include/linux/timer.h
Commit message (Collapse)AuthorAgeFilesLines
* timers: Drop a function prototypeRandy Dunlap2009-08-301-5/+0
| | | | | | | | | | Drop prototype for non-existent next_timer_interrupt() function. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Cc: akpm <akpm@linux-foundation.org> LKML-Reference: <4A9ADEC0.70306@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* timer stats: Optimize by adding quick check to avoid function callsHeiko Carstens2009-06-241-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the kernel is configured with CONFIG_TIMER_STATS but timer stats are runtime disabled we still get calls to __timer_stats_timer_set_start_info which initializes some fields in the corresponding struct timer_list. So add some quick checks in the the timer stats setup functions to avoid function calls to __timer_stats_timer_set_start_info when timer stats are disabled. In an artificial workload that does nothing but playing ping pong with a single tcp packet via loopback this decreases cpu consumption by 1 - 1.5%. This is part of a modified function trace output on SLES11: perl-2497 [00] 28630647177732388 [+ 125]: sk_reset_timer <-tcp_v4_rcv perl-2497 [00] 28630647177732513 [+ 125]: mod_timer <-sk_reset_timer perl-2497 [00] 28630647177732638 [+ 125]: __timer_stats_timer_set_start_info <-mod_timer perl-2497 [00] 28630647177732763 [+ 125]: __mod_timer <-mod_timer perl-2497 [00] 28630647177732888 [+ 125]: __timer_stats_timer_set_start_info <-__mod_timer perl-2497 [00] 28630647177733013 [+ 93]: lock_timer_base <-__mod_timer Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Mustafa Mesanovic <mustafa.mesanovic@de.ibm.com> Cc: Arjan van de Ven <arjan@infradead.org> LKML-Reference: <20090623153811.GA4641@osiris.boeblingen.de.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* timers: Framework for identifying pinned timersArun R Bharadwaj2009-05-131-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | * Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]: This patch creates a new framework for identifying cpu-pinned timers and hrtimers. This framework is needed because pinned timers are expected to fire on the same CPU on which they are queued. So it is essential to identify these and not migrate them, in case there are any. For regular timers, the currently existing add_timer_on() can be used queue pinned timers and subsequently mod_timer_pinned() can be used to modify the 'expires' field. For hrtimers, new modes HRTIMER_ABS_PINNED and HRTIMER_REL_PINNED are added to queue cpu-pinned hrtimer. [ tglx: use .._PINNED mode argument instead of creating tons of new functions ] Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Merge branch 'locking-for-linus' of ↵Linus Torvalds2009-03-301-9/+84
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (33 commits) lockdep: fix deadlock in lockdep_trace_alloc lockdep: annotate reclaim context (__GFP_NOFS), fix SLOB lockdep: annotate reclaim context (__GFP_NOFS), fix lockdep: build fix for !PROVE_LOCKING lockstat: warn about disabled lock debugging lockdep: use stringify.h lockdep: simplify check_prev_add_irq() lockdep: get_user_chars() redo lockdep: simplify get_user_chars() lockdep: add comments to mark_lock_irq() lockdep: remove macro usage from mark_held_locks() lockdep: fully reduce mark_lock_irq() lockdep: merge the !_READ mark_lock_irq() helpers lockdep: merge the _READ mark_lock_irq() helpers lockdep: simplify mark_lock_irq() helpers #3 lockdep: further simplify mark_lock_irq() helpers lockdep: simplify the mark_lock_irq() helpers lockdep: split up mark_lock_irq() lockdep: generate usage strings lockdep: generate the state bit definitions ...
| * timer: implement lockdep deadlock detectionJohannes Berg2009-02-141-9/+84
| | | | | | | | | | | | | | | | This modifies the timer code in a way to allow lockdep to detect deadlocks resulting from a lock being taken in the timer function as well as around the del_timer_sync() call. Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
* | timers: add mod_timer_pending()Ingo Molnar2009-02-181-20/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Impact: new timer API Based on an idea from Martin Josefsson with the help of Patrick McHardy and Stephen Hemminger: introduce the mod_timer_pending() API which is a mod_timer() offspring that is an invariant on already removed timers. (regular mod_timer() re-activates non-pending timers.) This is useful for the networking code in that it can allow unserialized mod_timer_pending() timer-forwarding calls, but a single del_timer*() will stop the timer from being reactivated again. Also while at it: - optimize the regular mod_timer() path some more, the timer-stat and a debug check was needlessly duplicated in __mod_timer(). - make the exports come straight after the function, as most other exports in timer.c already did. - eliminate __mod_timer() as an external API, change the users to mod_timer(). The regular mod_timer() code path is not impacted significantly, due to inlining optimizations and due to the simplifications. Based-on-patch-from: Stephen Hemminger <shemminger@vyatta.com> Acked-by: Stephen Hemminger <shemminger@vyatta.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Patrick McHardy <kaber@trash.net> Cc: netdev@vger.kernel.org Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Add round_jiffies_up and related routinesAlan Stern2008-11-061-0/+5
| | | | | | | | | | | | This patch (as1158b) adds round_jiffies_up() and friends. These routines work like the analogous round_jiffies() functions, except that they will never round down. The new routines will be useful for timeouts where we don't care exactly when the timer expires, provided it doesn't expire too soon. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* debugobjects: add timer specific object debugging codeThomas Gleixner2008-04-301-1/+22
| | | | | | | | | | | | | | Add calls to the generic object debugging infrastructure and provide fixup functions which allow to keep the system alive when recoverable problems have been detected by the object debugging core code. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Greg KH <greg@kroah.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* workqueue: make delayed_work_timer_fn() staticLi Zefan2008-02-081-2/+0
| | | | | | | | delayed_work_timer_fn() is a timer function, make it static. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Remove fastcall from linux/includeHarvey Harrison2008-02-081-2/+2
| | | | | | | [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* time: clean hungarian notation from timersPavel Machek2008-01-301-3/+3
| | | | | | | | | | Clean up hungarian notation from timer code. Signed-off-by: Pavel Machek <pavel@suse.cz> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* Add a flag to indicate deferrable timers in /proc/timer_statsVenki Pallipadi2007-07-161-11/+4
| | | | | | | | | | | | | | | | | | | Add a flag in /proc/timer_stats to indicate deferrable timers. This will let developers/users to differentiate between types of tiemrs in /proc/timer_stats. Deferrable timer and normal timer will appear in /proc/timer_stats as below. 10D, 1 swapper queue_delayed_work_on (delayed_work_timer_fn) 10, 1 swapper queue_delayed_work_on (delayed_work_timer_fn) Also version of timer_stats changes from v0.1 to v0.2 Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Acked-by: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Remove unnecessary includes of spinlock.h under include/linuxRobert P. J. Day2007-07-161-1/+0
| | | | | | | | | | Remove the obviously unnecessary includes of <linux/spinlock.h> under the include/linux/ directory, and fix the couple errors that are introduced as a result of that. Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* NOHZ: prevent multiplication overflow - stop timer for huge timeoutsThomas Gleixner2007-05-291-0/+6
| | | | | | | | | | | | | | | | | | | | | | | get_next_timer_interrupt() returns a delta of (LONG_MAX > 1) in case there is no timer pending. On 64 bit machines this results in a multiplication overflow in tick_nohz_stop_sched_tick(). Reported by: Dave Miller <davem@davemloft.net> Make the return value a constant and limit the return value to a 32 bit value. When the max timeout value is returned, we can safely stop the tick timer device. The max jiffies delta results in a 12 days timeout for HZ=1000. In the long term the get_next_timer_interrupt() code needs to be reworked to return ktime instead of jiffies, but we have to wait until the last users of the original NO_IDLE_HZ code are converted. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add support for deferrable timersVenki Pallipadi2007-05-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce a new flag for timers - deferrable: Timers that work normally when system is busy. But, will not cause CPU to come out of idle (just to service this timer), when CPU is idle. Instead, this timer will be serviced when CPU eventually wakes up with a subsequent non-deferrable timer. The main advantage of this is to avoid unnecessary timer interrupts when CPU is idle. If the routine currently called by a timer can wait until next event without any issues, this new timer can be used to setup timer event for that routine. This, with dynticks, allows CPUs to be lazy, allowing them to stay in idle for extended period of time by reducing unnecesary wakeup and thereby reducing the power consumption. This patch: Builds this new timer on top of existing timer infrastructure. It uses last bit in 'base' pointer of timer_list structure to store this deferrable timer flag. __next_timer_interrupt() function skips over these deferrable timers when CPU looks for next timer event for which it has to wake up. This is exported by a new interface init_timer_deferrable() that can be called in place of regular init_timer(). [akpm@linux-foundation.org: Privatise a #define] Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Dave Jones <davej@codemonkey.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Add debugging feature /proc/timer_statIngo Molnar2007-02-161-0/+54
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add /proc/timer_stats support: debugging feature to profile timer expiration. Both the starting site, process/PID and the expiration function is captured. This allows the quick identification of timer event sources in a system. Sample output: # echo 1 > /proc/timer_stats # cat /proc/timer_stats Timer Stats Version: v0.1 Sample period: 4.010 s 24, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick) 11, 0 swapper sk_reset_timer (tcp_delack_timer) 6, 0 swapper hrtimer_stop_sched_tick (hrtimer_sched_tick) 2, 1 swapper queue_delayed_work_on (delayed_work_timer_fn) 17, 0 swapper hrtimer_restart_sched_tick (hrtimer_sched_tick) 2, 1 swapper queue_delayed_work_on (delayed_work_timer_fn) 4, 2050 pcscd do_nanosleep (hrtimer_wakeup) 5, 4179 sshd sk_reset_timer (tcp_write_timer) 4, 2248 yum-updatesd schedule_timeout (process_timeout) 18, 0 swapper hrtimer_restart_sched_tick (hrtimer_sched_tick) 3, 0 swapper sk_reset_timer (tcp_delack_timer) 1, 1 swapper neigh_table_init_no_netlink (neigh_periodic_timer) 2, 1 swapper e1000_up (e1000_watchdog) 1, 1 init schedule_timeout (process_timeout) 100 total events, 25.24 events/sec [ cleanups and hrtimers support from Thomas Gleixner <tglx@linutronix.de> ] [bunk@stusta.de: nr_entries can become static] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] hrtimers: namespace and enum cleanupThomas Gleixner2007-02-161-1/+1
| | | | | | | | | | | | | | | | | | | - hrtimers did not use the hrtimer_restart enum and relied on the implict int representation. Fix the prototypes and the functions using the enums. - Use seperate name spaces for the enumerations - Convert hrtimer_restart macro to inline function - Add comments No functional changes. [akpm@osdl.org: fix input driver] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: john stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Dmitry Torokhov <dtor@mail.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] Extend next_timer_interrupt() to use a reference jiffieThomas Gleixner2007-02-161-0/+10
| | | | | | | | | | | | | | | | | | | For CONFIG_NO_HZ we need to calculate the next timer wheel event based on a given jiffie value. Extend the existing code to allow the extra 'now' argument. Provide a compability function for the existing implementations to call the function with now == jiffies. (This also solves the racyness of the original code vs. jiffies changing during the iteration.) No functional changes to existing users of this infrastructure. [ remove WARN_ON() that triggered on s390, by Carsten Otte <cotte@de.ibm.com> ] [ made new helper static, Adrian Bunk <bunk@stusta.de> ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: john stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] fix various kernel-doc in header filesRobert P. J. Day2007-01-261-2/+2
| | | | | | | | | | | Fix a number of kernel-doc entries for header files in include/linux by making sure they begin with the appropriate '/**' notation and use @var notation. Signed-off-by: Robert P. J. Day <rpjday@mindspring.com> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] round_jiffies infrastructureArjan van de Ven2006-12-101-0/+6
| | | | | | | | | | | | | | | | | | | | | | Introduce a round_jiffies() function as well as a round_jiffies_relative() function. These functions round a jiffies value to the next whole second. The primary purpose of this rounding is to cause all "we don't care exactly when" timers to happen at the same jiffy. This avoids multiple timers firing within the second for no real reason; with dynamic ticks these extra timers cause wakeups from deep sleep CPU sleep states and thus waste power. The exact wakeup moment is skewed by the cpu number, to avoid all cpus from waking up at the exact same time (and hitting the same lock/cachelines there) [akpm@osdl.org: fix variable type] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Don't include linux/config.h from anywhere else in include/David Woodhouse2006-04-261-1/+0
| | | | Signed-off-by: David Woodhouse <dwmw2@infradead.org>
* [PATCH] kill __init_timer_base in favor of boot_tvec_basesOleg Nesterov2006-03-311-4/+4
| | | | | | | | | | | | | Commit a4a6198b80cf82eb8160603c98da218d1bd5e104: [PATCH] tvec_bases too large for per-cpu data introduced "struct tvec_t_base_s boot_tvec_bases" which is visible at compile time. This means we can kill __init_timer_base and move timer_base_s's content into tvec_t_base_s. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] hrtimers: remove data fieldRoman Zippel2006-03-261-1/+2
| | | | | | | | | | | | The nanosleep cleanup allows to remove the data field of hrtimer. The callback function can use container_of() to get it's own data. Since the hrtimer structure is anyway embedded in other structures, this adds no overhead. Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Fix simple typosAndrzej Zaborowski2006-03-241-3/+3
| | | | | | This corrects some trivial errors in ARM docs and comments, Signed-off-by: Adrian Bunk <bunk@stusta.de>
* [PATCH] hrtimer: switch itimers to hrtimerThomas Gleixner2006-01-101-1/+1
| | | | | | | | | switch itimers to a hrtimers-based implementation Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] add_timer() of a pending timer is illegalAndrew Morton2005-10-301-1/+2
| | | | | | | | | In the recent timer rework we lost the check for an add_timer() of an already-pending timer. That check was useful for networking, so put it back. Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] remove timer debug fieldAndrew Morton2005-10-301-5/+0
| | | | | | | | | | | | | | | | Remove timer_list.magic and associated debugging code. I originally added this when a spinlock was added to timer_list - this meant that an all-zeroes timer became illegal and init_timer() was required. That spinlock isn't even there any more, although timer.base must now be initialised. I'll keep this debugging code in -mm. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] introduce setup_timer() helperOleg Nesterov2005-10-301-0/+9
| | | | | | | | | | | Every user of init_timer() also needs to initialize ->function and ->data fields. This patch adds a simple setup_timer() helper for that. The schedule_timeout() is patched as an example of usage. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] timer initialization cleanup: DEFINE_TIMERIngo Molnar2005-09-091-0/+4
| | | | | | | | | | Clean up timer initialization by introducing DEFINE_TIMER a'la DEFINE_SPINLOCK. Build and boot-tested on x86. A similar patch has been been in the -RT tree for some time. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] timers: introduce try_to_del_timer_sync()Oleg Nesterov2005-06-231-1/+3
| | | | | | | | | | | | | | | | | | This patch splits del_timer_sync() into 2 functions. The new one, try_to_del_timer_sync(), returns -1 when it hits executing timer. It can be used in interrupt context, or when the caller hold locks which can prevent completion of the timer's handler. NOTE. Currently it can't be used in interrupt context in UP case, because ->running_timer is used only with CONFIG_SMP. Should the need arise, it is possible to kill #ifdef CONFIG_SMP in set_running_timer(), it is cheap. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] timers fixes/improvementsOleg Nesterov2005-06-231-21/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch tries to solve following problems: 1. del_timer_sync() is racy. The timer can be fired again after del_timer_sync have checked all cpus and before it will recheck timer_pending(). 2. It has scalability problems. All cpus are scanned to determine if the timer is running on that cpu. With this patch del_timer_sync is O(1) and no slower than plain del_timer(pending_timer), unless it has to actually wait for completion of the currently running timer. The only restriction is that the recurring timer should not use add_timer_on(). 3. The timers are not serialized wrt to itself. If CPU_0 does mod_timer(jiffies+1) while the timer is currently running on CPU 1, it is quite possible that local interrupt on CPU_0 will start that timer before it finished on CPU_1. 4. The timers locking is suboptimal. __mod_timer() takes 3 locks at once and still requires wmb() in del_timer/run_timers. The new implementation takes 2 locks sequentially and does not need memory barriers. Currently ->base != NULL means that the timer is pending. In that case ->base.lock is used to lock the timer. __mod_timer also takes timer->lock because ->base can be == NULL. This patch uses timer->entry.next != NULL as indication that the timer is pending. So it does __list_del(), entry->next = NULL instead of list_del() when the timer is deleted. The ->base field is used for hashed locking only, it is initialized in init_timer() which sets ->base = per_cpu(tvec_bases). When the tvec_bases.lock is locked, it means that all timers which are tied to this base via timer->base are locked, and the base itself is locked too. So __run_timers/migrate_timers can safely modify all timers which could be found on ->tvX lists (pending timers). When the timer's base is locked, and the timer removed from ->entry list (which means that _run_timers/migrate_timers can't see this timer), it is possible to set timer->base = NULL and drop the lock: the timer remains locked. This patch adds lock_timer_base() helper, which waits for ->base != NULL, locks the ->base, and checks it is still the same. __mod_timer() schedules the timer on the local CPU and changes it's base. However, it does not lock both old and new bases at once. It locks the timer via lock_timer_base(), deletes the timer, sets ->base = NULL, and unlocks old base. Then __mod_timer() locks new_base, sets ->base = new_base, and adds this timer. This simplifies the code, because AB-BA deadlock is not possible. __mod_timer() also ensures that the timer's base is not changed while the timer's handler is running on the old base. __run_timers(), del_timer() do not change ->base anymore, they only clear pending flag. So del_timer_sync() can test timer->base->running_timer == timer to detect whether it is running or not. We don't need timer_list->lock anymore, this patch kills it. We also don't need barriers. del_timer() and __run_timers() used smp_wmb() before clearing timer's pending flag. It was needed because __mod_timer() did not lock old_base if the timer is not pending, so __mod_timer()->list_add() could race with del_timer()->list_del(). With this patch these functions are serialized through base->lock. One problem. TIMER_INITIALIZER can't use per_cpu(tvec_bases). So this patch adds global struct timer_base_s { spinlock_t lock; struct timer_list *running_timer; } __init_timer_base; which is used by TIMER_INITIALIZER. The corresponding fields in tvec_t_base_s struct are replaced by struct timer_base_s t_base. It is indeed ugly. But this can't have scalability problems. The global __init_timer_base.lock is used only when __mod_timer() is called for the first time AND the timer was compile time initialized. After that the timer migrates to the local CPU. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Renaud Lienhart <renaud.lienhart@free.fr> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds2005-04-161-0/+102
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-27 05:20:04 +0000