- 22 10月, 2010 1 次提交
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由 Yong Zhang 提交于
On UP try_to_del_timer_sync() is mapped to del_timer() which does not take the running timer callback into account, so it has different semantics. Remove the SMP dependency of try_to_del_timer_sync() by using base->running_timer in the UP case as well. [ tglx: Removed set_running_timer() inline and tweaked the changelog ] Signed-off-by: NYong Zhang <yong.zhang0@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Acked-by: NOleg Nesterov <oleg@redhat.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 21 10月, 2010 3 次提交
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由 Phil Carmody 提交于
Currently, you have to just define a delayed_work uninitialised, and then initialise it before first use. That's a tad clumsy. At risk of playing mind-games with the compiler, fooling it into doing pointer arithmetic with compile-time-constants, this lets clients properly initialise delayed work with deferrable timers statically. This patch was inspired by the issues which lead Artem Bityutskiy to commit 8eab945c ("sunrpc: make the cache cleaner workqueue deferrable"). Signed-off-by: NPhil Carmody <ext-phil.2.carmody@nokia.com> Acked-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com> Cc: Arjan van de Ven <arjan@infradead.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Changli Gao 提交于
TIMER_INITIALIZER() should initialize the field slack of timer_list as __init_timer() does. Signed-off-by: NChangli Gao <xiaosuo@gmail.com> Cc: Arjan van de Ven <arjan@infradead.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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由 Richard Kennedy 提交于
Reorder struct timer_list to remove 8 bytes of alignment padding on 64 bit builds when CONFIG_TIMER_STATS is selected. timer_list is widely used across the kernel so many structures will benefit and shrink in size. For example, with my config on x86_64 per_cpu_dm_data shrinks from 136 to 128 bytes and ahci_port_priv shrinks from 1032 to 968 bytes. Signed-off-by: NRichard Kennedy <richard@rsk.demon.co.uk> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 03 8月, 2010 1 次提交
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由 Jesse Barnes 提交于
In some cases (for instance with kernel threads) it may be desireable to use on-stack deferrable timers to get their power saving benefits. Add interfaces to support this for the IPS driver. Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org> Signed-off-by: NMatthew Garrett <mjg@redhat.com>
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- 07 4月, 2010 1 次提交
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由 Arjan van de Ven 提交于
While HR timers have had the concept of timer slack for quite some time now, the legacy timers lacked this concept, and had to make do with round_jiffies() and friends. Timer slack is important for power management; grouping timers reduces the number of wakeups which in turn reduces power consumption. This patch introduces timer slack to the legacy timers using the following pieces: * A slack field in the timer struct * An api (set_timer_slack) that callers can use to set explicit timer slack * A default slack of 0.4% of the requested delay for callers that do not set any explicit slack * Rounding code that is part of mod_timer() that tries to group timers around jiffies values every 'power of two' (so quick timers will group around every 2, but longer timers will group around every 4, 8, 16, 32 etc) Signed-off-by: NArjan van de Ven <arjan@linux.intel.com> Cc: johnstul@us.ibm.com Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 31 8月, 2009 1 次提交
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由 Randy Dunlap 提交于
Drop prototype for non-existent next_timer_interrupt() function. Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com> Cc: akpm <akpm@linux-foundation.org> LKML-Reference: <4A9ADEC0.70306@oracle.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 24 6月, 2009 1 次提交
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由 Heiko Carstens 提交于
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: NHeiko 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: NIngo Molnar <mingo@elte.hu>
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- 13 5月, 2009 1 次提交
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由 Arun R Bharadwaj 提交于
* 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: NArun R Bharadwaj <arun@linux.vnet.ibm.com> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 19 2月, 2009 1 次提交
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由 Ingo Molnar 提交于
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: NStephen 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: NIngo Molnar <mingo@elte.hu>
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- 15 2月, 2009 1 次提交
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由 Johannes Berg 提交于
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: NJohannes Berg <johannes@sipsolutions.net>
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- 06 11月, 2008 1 次提交
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由 Alan Stern 提交于
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: NAlan Stern <stern@rowland.harvard.edu> Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
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- 30 4月, 2008 1 次提交
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由 Thomas Gleixner 提交于
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: NThomas Gleixner <tglx@linutronix.de> Acked-by: NIngo 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: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 2月, 2008 2 次提交
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由 Li Zefan 提交于
delayed_work_timer_fn() is a timer function, make it static. Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Harvey Harrison 提交于
[akpm@linux-foundation.org: coding-style fixes] Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 30 1月, 2008 1 次提交
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由 Pavel Machek 提交于
Clean up hungarian notation from timer code. Signed-off-by: NPavel Machek <pavel@suse.cz> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
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- 17 7月, 2007 2 次提交
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由 Venki Pallipadi 提交于
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: NVenkatesh Pallipadi <venkatesh.pallipadi@intel.com> Acked-by: NIngo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Robert P. J. Day 提交于
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: NRobert P. J. Day <rpjday@mindspring.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 30 5月, 2007 1 次提交
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由 Thomas Gleixner 提交于
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: NThomas Gleixner <tglx@linutronix.de> Acked-off-by: NDavid S. Miller <davem@davemloft.net> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 09 5月, 2007 1 次提交
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由 Venki Pallipadi 提交于
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: NVenkatesh 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: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 17 2月, 2007 3 次提交
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由 Ingo Molnar 提交于
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: NIngo Molnar <mingo@elte.hu> Signed-off-by: NThomas 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: NAdrian Bunk <bunk@stusta.de> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Thomas Gleixner 提交于
- 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: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NIngo 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: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Thomas Gleixner 提交于
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: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NIngo Molnar <mingo@elte.hu> Cc: john stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 27 1月, 2007 1 次提交
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由 Robert P. J. Day 提交于
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: NRobert P. J. Day <rpjday@mindspring.com> Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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- 11 12月, 2006 1 次提交
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由 Arjan van de Ven 提交于
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: NArjan van de Ven <arjan@linux.intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 26 4月, 2006 1 次提交
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由 David Woodhouse 提交于
Signed-off-by: NDavid Woodhouse <dwmw2@infradead.org>
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- 01 4月, 2006 1 次提交
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由 Oleg Nesterov 提交于
Commit a4a6198b: [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: NOleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 27 3月, 2006 1 次提交
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由 Roman Zippel 提交于
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: NRoman Zippel <zippel@linux-m68k.org> Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 25 3月, 2006 1 次提交
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由 Andrzej Zaborowski 提交于
This corrects some trivial errors in ARM docs and comments, Signed-off-by: NAdrian Bunk <bunk@stusta.de>
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- 11 1月, 2006 1 次提交
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由 Thomas Gleixner 提交于
switch itimers to a hrtimers-based implementation Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 31 10月, 2005 3 次提交
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由 Andrew Morton 提交于
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: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Andrew Morton 提交于
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: NAlexey Dobriyan <adobriyan@gmail.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Oleg Nesterov 提交于
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: NOleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 10 9月, 2005 1 次提交
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由 Ingo Molnar 提交于
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: NIngo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 24 6月, 2005 2 次提交
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由 Oleg Nesterov 提交于
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: NOleg Nesterov <oleg@tv-sign.ru> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Oleg Nesterov 提交于
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: NOleg Nesterov <oleg@tv-sign.ru> Acked-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NRenaud Lienhart <renaud.lienhart@free.fr> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 17 4月, 2005 1 次提交
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由 Linus Torvalds 提交于
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!
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