1. 16 Jul, 2007 2 commits
  2. 29 May, 2007 1 commit
  3. 08 May, 2007 1 commit
    • Venki Pallipadi's avatar
      Add support for deferrable timers · 6e453a67
      Venki Pallipadi authored
      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
      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: default avatarVenkatesh 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
  4. 16 Feb, 2007 3 commits
    • Ingo Molnar's avatar
      [PATCH] Add debugging feature /proc/timer_stat · 82f67cd9
      Ingo Molnar authored
      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: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas 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: default avatarAdrian Bunk <bunk@stusta.de>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    • Thomas Gleixner's avatar
      [PATCH] hrtimers: namespace and enum cleanup · c9cb2e3d
      Thomas Gleixner authored
      - 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: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarIngo 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: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    • Thomas Gleixner's avatar
      [PATCH] Extend next_timer_interrupt() to use a reference jiffie · fd064b9b
      Thomas Gleixner authored
      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: default avatarThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Cc: john stultz <johnstul@us.ibm.com>
      Cc: Roman Zippel <zippel@linux-m68k.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
  5. 26 Jan, 2007 1 commit
  6. 10 Dec, 2006 1 commit
    • Arjan van de Ven's avatar
      [PATCH] round_jiffies infrastructure · 4c36a5de
      Arjan van de Ven authored
      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
      [akpm@osdl.org: fix variable type]
      Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
  7. 26 Apr, 2006 1 commit
  8. 31 Mar, 2006 1 commit
  9. 26 Mar, 2006 1 commit
  10. 24 Mar, 2006 1 commit
  11. 10 Jan, 2006 1 commit
  12. 30 Oct, 2005 3 commits
  13. 09 Sep, 2005 1 commit
  14. 23 Jun, 2005 2 commits
    • Oleg Nesterov's avatar
      [PATCH] timers: introduce try_to_del_timer_sync() · fd450b73
      Oleg Nesterov authored
      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: default avatarOleg Nesterov <oleg@tv-sign.ru>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    • Oleg Nesterov's avatar
      [PATCH] timers fixes/improvements · 55c888d6
      Oleg Nesterov authored
      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
      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
      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
      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
      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: default avatarOleg Nesterov <oleg@tv-sign.ru>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarRenaud Lienhart <renaud.lienhart@free.fr>
      Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
  15. 16 Apr, 2005 1 commit
    • Linus Torvalds's avatar
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds authored
      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!