1. 18 Aug, 2008 1 commit
  2. 13 Aug, 2008 1 commit
  3. 11 Aug, 2008 5 commits
    • Peter Zijlstra's avatar
      lockdep: fix debug_lock_alloc · 0f2bc27b
      Peter Zijlstra authored
      When we enable DEBUG_LOCK_ALLOC but do not enable PROVE_LOCKING and or
      LOCK_STAT, lock_alloc() and lock_release() turn into nops, even though
      we should be doing hlock checking (check=1).
      
      This causes a false warning and a lockdep self-disable.
      
      Rectify this.
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      0f2bc27b
    • Rabin Vincent's avatar
      lockdep: handle chains involving classes defined in modules · 8bfe0298
      Rabin Vincent authored
      Solve this by marking the classes as unused and not printing information
      about the unused classes.
      Reported-by: default avatarEric Sesterhenn <snakebyte@gmx.de>
      Signed-off-by: default avatarRabin Vincent <rabin@rab.in>
      Acked-by: default avatarHuang Ying <ying.huang@intel.com>
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      8bfe0298
    • Peter Zijlstra's avatar
      lockdep: lock protection locks · 7531e2f3
      Peter Zijlstra authored
      On Fri, 2008-08-01 at 16:26 -0700, Linus Torvalds wrote:
      
      > On Fri, 1 Aug 2008, David Miller wrote:
      > >
      > > Taking more than a few locks of the same class at once is bad
      > > news and it's better to find an alternative method.
      >
      > It's not always wrong.
      >
      > If you can guarantee that anybody that takes more than one lock of a
      > particular class will always take a single top-level lock _first_, then
      > that's all good. You can obviously screw up and take the same lock _twice_
      > (which will deadlock), but at least you cannot get into ABBA situations.
      >
      > So maybe the right thing to do is to just teach lockdep about "lock
      > protection locks". That would have solved the multi-queue issues for
      > networking too - all the actual network drivers would still have taken
      > just their single queue lock, but the one case that needs to take all of
      > them would have taken a separate top-level lock first.
      >
      > Never mind that the multi-queue locks were always taken in the same order:
      > it's never wrong to just have some top-level serialization, and anybody
      > who needs to take <n> locks might as well do <n+1>, because they sure as
      > hell aren't going to be on _any_ fastpaths.
      >
      > So the simplest solution really sounds like just teaching lockdep about
      > that one special case. It's not "nesting" exactly, although it's obviously
      > related to it.
      
      Do as Linus suggested. The lock protection lock is called nest_lock.
      
      Note that we still have the MAX_LOCK_DEPTH (48) limit to consider, so anything
      that spills that it still up shit creek.
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      7531e2f3
    • Dave Jones's avatar
      lockdep: shrink held_lock structure · f82b217e
      Dave Jones authored
      struct held_lock {
              u64                        prev_chain_key;       /*     0     8 */
              struct lock_class *        class;                /*     8     8 */
              long unsigned int          acquire_ip;           /*    16     8 */
              struct lockdep_map *       instance;             /*    24     8 */
              int                        irq_context;          /*    32     4 */
              int                        trylock;              /*    36     4 */
              int                        read;                 /*    40     4 */
              int                        check;                /*    44     4 */
              int                        hardirqs_off;         /*    48     4 */
      
              /* size: 56, cachelines: 1 */
              /* padding: 4 */
              /* last cacheline: 56 bytes */
      };
      
      struct held_lock {
              u64                        prev_chain_key;       /*     0     8 */
              long unsigned int          acquire_ip;           /*     8     8 */
              struct lockdep_map *       instance;             /*    16     8 */
              unsigned int               class_idx:11;         /*    24:21  4 */
              unsigned int               irq_context:2;        /*    24:19  4 */
              unsigned int               trylock:1;            /*    24:18  4 */
              unsigned int               read:2;               /*    24:16  4 */
              unsigned int               check:2;              /*    24:14  4 */
              unsigned int               hardirqs_off:1;       /*    24:13  4 */
      
              /* size: 32, cachelines: 1 */
              /* padding: 4 */
              /* bit_padding: 13 bits */
              /* last cacheline: 32 bytes */
      };
      
      [mingo@elte.hu: shrunk hlock->class too]
      [peterz@infradead.org: fixup bit sizes]
      Signed-off-by: default avatarDave Jones <davej@redhat.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      f82b217e
    • Peter Zijlstra's avatar
      lockdep: lock_set_subclass - reset a held lock's subclass · 64aa348e
      Peter Zijlstra authored
      this can be used to reset a held lock's subclass, for arbitrary-depth
      iterated data structures such as trees or lists which have per-node
      locks.
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      64aa348e
  4. 31 Jul, 2008 1 commit
    • David Miller's avatar
      lockdep: fix combinatorial explosion in lock subgraph traversal · 419ca3f1
      David Miller authored
      When we traverse the graph, either forwards or backwards, we
      are interested in whether a certain property exists somewhere
      in a node reachable in the graph.
      
      Therefore it is never necessary to traverse through a node more
      than once to get a correct answer to the given query.
      
      Take advantage of this property using a global ID counter so that we
      need not clear all the markers in all the lock_class entries before
      doing a traversal.  A new ID is choosen when we start to traverse, and
      we continue through a lock_class only if it's ID hasn't been marked
      with the new value yet.
      
      This short-circuiting is essential especially for high CPU count
      systems.  The scheduler has a runqueue per cpu, and needs to take
      two runqueue locks at a time, which leads to long chains of
      backwards and forwards subgraphs from these runqueue lock nodes.
      Without the short-circuit implemented here, a graph traversal on
      a runqueue lock can take up to (1 << (N - 1)) checks on a system
      with N cpus.
      
      For anything more than 16 cpus or so, lockdep will eventually bring
      the machine to a complete standstill.
      Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      419ca3f1
  5. 14 Jul, 2008 1 commit
    • Ingo Molnar's avatar
      lockdep: fix ftrace irq tracing false positive · 992860e9
      Ingo Molnar authored
      fix this false positive:
      
      [    0.020000] ------------[ cut here ]------------
      [    0.020000] WARNING: at kernel/lockdep.c:2718 check_flags+0x14a/0x170()
      [    0.020000] Modules linked in:
      [    0.020000] Pid: 0, comm: swapper Not tainted 2.6.26-tip-00343-gd7e5521-dirty #14486
      [    0.020000]  [<c01312e4>] warn_on_slowpath+0x54/0x80
      [    0.020000]  [<c067e451>] ? _spin_unlock_irqrestore+0x61/0x70
      [    0.020000]  [<c0131bb1>] ? release_console_sem+0x201/0x210
      [    0.020000]  [<c0143d65>] ? __kernel_text_address+0x35/0x40
      [    0.020000]  [<c010562e>] ? dump_trace+0x5e/0x140
      [    0.020000]  [<c01518b5>] ? __lock_acquire+0x245/0x820
      [    0.020000]  [<c015063a>] check_flags+0x14a/0x170
      [    0.020000]  [<c0151ed8>] ? lock_acquire+0x48/0xc0
      [    0.020000]  [<c0151ee1>] lock_acquire+0x51/0xc0
      [    0.020000]  [<c014a16c>] ? down+0x2c/0x40
      [    0.020000]  [<c010a609>] ? sched_clock+0x9/0x10
      [    0.020000]  [<c067e7b2>] _write_lock+0x32/0x60
      [    0.020000]  [<c013797f>] ? request_resource+0x1f/0xb0
      [    0.020000]  [<c013797f>] request_resource+0x1f/0xb0
      [    0.020000]  [<c02f89ad>] vgacon_startup+0x2bd/0x3e0
      [    0.020000]  [<c094d62a>] con_init+0x19/0x22f
      [    0.020000]  [<c0330c7c>] ? tty_register_ldisc+0x5c/0x70
      [    0.020000]  [<c094cf49>] console_init+0x20/0x2e
      [    0.020000]  [<c092a969>] start_kernel+0x20c/0x379
      [    0.020000]  [<c092a516>] ? unknown_bootoption+0x0/0x1f6
      [    0.020000]  [<c092a099>] __init_begin+0x99/0xa1
      [    0.020000]  =======================
      [    0.020000] ---[ end trace 4eaa2a86a8e2da22 ]---
      [    0.020000] possible reason: unannotated irqs-on.
      [    0.020000] irq event stamp: 0
      
      which occurs if CONFIG_TRACE_IRQFLAGS=y, CONFIG_DEBUG_LOCKDEP=y,
      but CONFIG_PROVE_LOCKING is disabled.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      992860e9
  6. 23 Jun, 2008 1 commit
  7. 20 Jun, 2008 1 commit
  8. 23 May, 2008 4 commits
    • Steven Rostedt's avatar
      lockdep: update lockdep_recursion on graph_lock · bb065afb
      Steven Rostedt authored
      With the introduction of ftrace, it is possible to recurse into
      the lockdep functions via the mcount call. To prevent possible
      lockups, updating the lockdep_recursion counter on grabbing the internal
      lockdep_lock should prevent deadlocks.
      Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      bb065afb
    • Steven Rostedt's avatar
      ftrace: use Makefile to remove tracing from lockdep · 1d09daa5
      Steven Rostedt authored
      This patch removes the "notrace" annotation from lockdep and adds the debugging
      files in the kernel director to those that should not be compiled with
      "-pg" mcount tracing.
      Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      1d09daa5
    • Steven Rostedt's avatar
      ftrace: lockdep notrace annotations · 0764d23c
      Steven Rostedt authored
      Add notrace annotations to lockdep to keep ftrace from causing
      recursive problems with lock tracing and debugging.
      Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      0764d23c
    • Steven Rostedt's avatar
      ftrace: trace irq disabled critical timings · 81d68a96
      Steven Rostedt authored
      This patch adds latency tracing for critical timings
      (how long interrupts are disabled for).
      
       "irqsoff" is added to /debugfs/tracing/available_tracers
      
      Note:
        tracing_max_latency
          also holds the max latency for irqsoff (in usecs).
         (default to large number so one must start latency tracing)
      
        tracing_thresh
          threshold (in usecs) to always print out if irqs off
          is detected to be longer than stated here.
          If irq_thresh is non-zero, then max_irq_latency
          is ignored.
      
      Here's an example of a trace with ftrace_enabled = 0
      
      =======
      preemption latency trace v1.1.5 on 2.6.24-rc7
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      --------------------------------------------------------------------
       latency: 100 us, #3/3, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
          -----------------
          | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
          -----------------
       => started at: _spin_lock_irqsave+0x2a/0xb7
       => ended at:   _spin_unlock_irqrestore+0x32/0x5f
      
                       _------=> CPU#
                      / _-----=> irqs-off
                     | / _----=> need-resched
                     || / _---=> hardirq/softirq
                     ||| / _--=> preempt-depth
                     |||| /
                     |||||     delay
         cmd     pid ||||| time  |   caller
            \   /    |||||   \   |   /
       swapper-0     1d.s3    0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
       swapper-0     1d.s3  100us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
       swapper-0     1d.s3  100us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)
      
      vim:ft=help
      =======
      
      And this is a trace with ftrace_enabled == 1
      
      =======
      preemption latency trace v1.1.5 on 2.6.24-rc7
      --------------------------------------------------------------------
       latency: 102 us, #12/12, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
          -----------------
          | task: swapper-0 (uid:0 nice:0 policy:0 rt_prio:0)
          -----------------
       => started at: _spin_lock_irqsave+0x2a/0xb7
       => ended at:   _spin_unlock_irqrestore+0x32/0x5f
      
                       _------=> CPU#
                      / _-----=> irqs-off
                     | / _----=> need-resched
                     || / _---=> hardirq/softirq
                     ||| / _--=> preempt-depth
                     |||| /
                     |||||     delay
         cmd     pid ||||| time  |   caller
            \   /    |||||   \   |   /
       swapper-0     1dNs3    0us+: _spin_lock_irqsave+0x2a/0xb7 (e1000_update_stats+0x47/0x64c [e1000])
       swapper-0     1dNs3   46us : e1000_read_phy_reg+0x16/0x225 [e1000] (e1000_update_stats+0x5e2/0x64c [e1000])
       swapper-0     1dNs3   46us : e1000_swfw_sync_acquire+0x10/0x99 [e1000] (e1000_read_phy_reg+0x49/0x225 [e1000])
       swapper-0     1dNs3   46us : e1000_get_hw_eeprom_semaphore+0x12/0xa6 [e1000] (e1000_swfw_sync_acquire+0x36/0x99 [e1000])
       swapper-0     1dNs3   47us : __const_udelay+0x9/0x47 (e1000_read_phy_reg+0x116/0x225 [e1000])
       swapper-0     1dNs3   47us+: __delay+0x9/0x50 (__const_udelay+0x45/0x47)
       swapper-0     1dNs3   97us : preempt_schedule+0xc/0x84 (__delay+0x4e/0x50)
       swapper-0     1dNs3   98us : e1000_swfw_sync_release+0xc/0x55 [e1000] (e1000_read_phy_reg+0x211/0x225 [e1000])
       swapper-0     1dNs3   99us+: e1000_put_hw_eeprom_semaphore+0x9/0x35 [e1000] (e1000_swfw_sync_release+0x50/0x55 [e1000])
       swapper-0     1dNs3  101us : _spin_unlock_irqrestore+0xe/0x5f (e1000_update_stats+0x641/0x64c [e1000])
       swapper-0     1dNs3  102us : _spin_unlock_irqrestore+0x32/0x5f (e1000_update_stats+0x641/0x64c [e1000])
       swapper-0     1dNs3  102us : trace_hardirqs_on_caller+0x75/0x89 (_spin_unlock_irqrestore+0x32/0x5f)
      
      vim:ft=help
      =======
      Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      81d68a96
  9. 25 Feb, 2008 1 commit
  10. 25 Jan, 2008 1 commit
    • Ingo Molnar's avatar
      softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks · 82a1fcb9
      Ingo Molnar authored
      this patch extends the soft-lockup detector to automatically
      detect hung TASK_UNINTERRUPTIBLE tasks. Such hung tasks are
      printed the following way:
      
       ------------------>
       INFO: task prctl:3042 blocked for more than 120 seconds.
       "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message
       prctl         D fd5e3793     0  3042   2997
              f6050f38 00000046 00000001 fd5e3793 00000009 c06d8264 c06dae80 00000286
              f6050f40 f6050f00 f7d34d90 f7d34fc8 c1e1be80 00000001 f6050000 00000000
              f7e92d00 00000286 f6050f18 c0489d1a f6050f40 00006605 00000000 c0133a5b
       Call Trace:
        [<c04883a5>] schedule_timeout+0x6d/0x8b
        [<c04883d8>] schedule_timeout_uninterruptible+0x15/0x17
        [<c0133a76>] msleep+0x10/0x16
        [<c0138974>] sys_prctl+0x30/0x1e2
        [<c0104c52>] sysenter_past_esp+0x5f/0xa5
        =======================
       2 locks held by prctl/3042:
       #0:  (&sb->s_type->i_mutex_key#5){--..}, at: [<c0197d11>] do_fsync+0x38/0x7a
       #1:  (jbd_handle){--..}, at: [<c01ca3d2>] journal_start+0xc7/0xe9
       <------------------
      
      the current default timeout is 120 seconds. Such messages are printed
      up to 10 times per bootup. If the system has crashed already then the
      messages are not printed.
      
      if lockdep is enabled then all held locks are printed as well.
      
      this feature is a natural extension to the softlockup-detector (kernel
      locked up without scheduling) and to the NMI watchdog (kernel locked up
      with IRQs disabled).
      
      [ Gautham R Shenoy <ego@in.ibm.com>: CPU hotplug fixes. ]
      [ Andrew Morton <akpm@linux-foundation.org>: build warning fix. ]
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
      82a1fcb9
  11. 24 Jan, 2008 1 commit
  12. 16 Jan, 2008 1 commit
  13. 07 Dec, 2007 1 commit
  14. 05 Dec, 2007 2 commits
    • Oleg Nesterov's avatar
      lockdep: in_range() fix · 54561783
      Oleg Nesterov authored
      Torsten Kaiser wrote:
      
      | static inline int in_range(const void *start, const void *addr, const void *end)
      | {
      |         return addr >= start && addr <= end;
      | }
      | This  will return true, if addr is in the range of start (including)
      | to end (including).
      |
      | But debug_check_no_locks_freed() seems does:
      | const void *mem_to = mem_from + mem_len
      | -> mem_to is the last byte of the freed range, that fits in_range
      | lock_from = (void *)hlock->instance;
      | -> first byte of the lock
      | lock_to = (void *)(hlock->instance + 1);
      | -> first byte of the next lock, not last byte of the lock that is being checked!
      |
      | The test is:
      | if (!in_range(mem_from, lock_from, mem_to) &&
      |                                         !in_range(mem_from, lock_to, mem_to))
      |                         continue;
      | So it tests, if the first byte of the lock is in the range that is freed ->OK
      | And if the first byte of the *next* lock is in the range that is freed
      | -> Not OK.
      
      We can also simplify in_range checks, we need only 2 comparisons, not 4.
      If the lock is not in memory range, it should be either at the left of range
      or at the right.
      Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      54561783
    • Ingo Molnar's avatar
      lockdep: fix debug_show_all_locks() · 85684873
      Ingo Molnar authored
      fix the oops that can be seen in:
      
         http://bugzilla.kernel.org/attachment.cgi?id=13828&action=view
      
      it is not safe to print the locks of running tasks.
      
      (even with this fix we have a small race - but this is a debug
       function after all.)
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      85684873
  15. 28 Oct, 2007 1 commit
  16. 19 Oct, 2007 2 commits
  17. 11 Oct, 2007 2 commits
  18. 19 Jul, 2007 7 commits
    • Johannes Berg's avatar
      lockdep debugging: give stacktrace for init_error · c71063c9
      Johannes Berg authored
      When I started adding support for lockdep to 64-bit powerpc, I got a
      lockdep_init_error and with this patch was able to pinpoint why and where
      to put lockdep_init().  Let's support this generally for others adding
      lockdep support to their architecture.
      Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
      Cc: Ingo Molnar <mingo@elte.hu>
      Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
      Cc: Arjan van de Ven <arjan@infradead.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      c71063c9
    • Peter Zijlstra's avatar
      lockstat: measure lock bouncing · 96645678
      Peter Zijlstra authored
          __acquire
              |
             lock _____
              |        \
              |    __contended
              |         |
              |        wait
              | _______/
              |/
              |
         __acquired
              |
         __release
              |
           unlock
      
      We measure acquisition and contention bouncing.
      
      This is done by recording a cpu stamp in each lock instance.
      
      Contention bouncing requires the cpu stamp to be set on acquisition. Hence we
      move __acquired into the generic path.
      
      __acquired is then used to measure acquisition bouncing by comparing the
      current cpu with the old stamp before replacing it.
      
      __contended is used to measure contention bouncing (only useful for preemptable
      locks)
      
      [akpm@linux-foundation.org: cleanups]
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      96645678
    • Peter Zijlstra's avatar
      lockdep: various fixes · 4b32d0a4
      Peter Zijlstra authored
       - update the copyright notices
       - use the default hash function
       - fix a thinko in a BUILD_BUG_ON
       - add a WARN_ON to spot inconsitent naming
       - fix a termination issue in /proc/lock_stat
      
      [akpm@linux-foundation.org: cleanups]
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4b32d0a4
    • Peter Zijlstra's avatar
      lockstat: human readability tweaks · c46261de
      Peter Zijlstra authored
      Present all this fancy new lock statistics information:
      
      *warning, _wide_ output ahead*
      
      (output edited for purpose of brevity)
      
       # cat /proc/lock_stat
      lock_stat version 0.1
      -----------------------------------------------------------------------------------------------------------------------------------------------------------------
                                    class name    contentions   waittime-min   waittime-max waittime-total   acquisitions   holdtime-min   holdtime-max holdtime-total
      -----------------------------------------------------------------------------------------------------------------------------------------------------------------
      
                               &inode->i_mutex:         14458           6.57      398832.75     2469412.23        6768876           0.34    11398383.65   339410830.89
                               ---------------
                               &inode->i_mutex           4486          [<ffffffff802a08f9>] pipe_wait+0x86/0x8d
                               &inode->i_mutex              0          [<ffffffff802a01e8>] pipe_write_fasync+0x29/0x5d
                               &inode->i_mutex              0          [<ffffffff802a0e18>] pipe_read+0x74/0x3a5
                               &inode->i_mutex              0          [<ffffffff802a1a6a>] do_lookup+0x81/0x1ae
      
      .................................................................................................................................................................
      
                    &inode->i_data.tree_lock-W:           491           0.27          62.47         493.89        2477833           0.39         468.89     1146584.25
                    &inode->i_data.tree_lock-R:            65           0.44           4.27          48.78       26288792           0.36         184.62    10197458.24
                    --------------------------
                      &inode->i_data.tree_lock             46          [<ffffffff80277095>] __do_page_cache_readahead+0x69/0x24f
                      &inode->i_data.tree_lock             31          [<ffffffff8026f9fb>] add_to_page_cache+0x31/0xba
                      &inode->i_data.tree_lock              0          [<ffffffff802770ee>] __do_page_cache_readahead+0xc2/0x24f
                      &inode->i_data.tree_lock              0          [<ffffffff8026f6e4>] find_get_page+0x1a/0x58
      
      .................................................................................................................................................................
      
                            proc_inum_idr.lock:             0           0.00           0.00           0.00             36           0.00          65.60         148.26
                              proc_subdir_lock:             0           0.00           0.00           0.00        3049859           0.00         106.81     1563212.42
                              shrinker_rwsem-W:             0           0.00           0.00           0.00              5           0.00           1.73           3.68
                              shrinker_rwsem-R:             0           0.00           0.00           0.00            633           2.57         246.57       10909.76
      
      'contentions' and 'acquisitions' are the number of such events measured (since
      the last reset). The waittime- and holdtime- (min, max, total) numbers are
      presented in microseconds.
      
      If there are any contention points, the lock class is presented in the block
      format (as i_mutex and tree_lock above), otherwise a single line of output is
      presented.
      
      The output is sorted on absolute number of contentions (read + write), this
      should get the worst offenders presented first, so that:
      
       # grep : /proc/lock_stat | head
      
      will quickly show who's bad.
      
      The stats can be reset using:
      
       # echo 0 > /proc/lock_stat
      
      [bunk@stusta.de: make 2 functions static]
      [akpm@linux-foundation.org: fix printk warning]
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Acked-by: default avatarJason Baron <jbaron@redhat.com>
      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>
      c46261de
    • Peter Zijlstra's avatar
      lockstat: core infrastructure · f20786ff
      Peter Zijlstra authored
      Introduce the core lock statistics code.
      
      Lock statistics provides lock wait-time and hold-time (as well as the count
      of corresponding contention and acquisitions events). Also, the first few
      call-sites that encounter contention are tracked.
      
      Lock wait-time is the time spent waiting on the lock. This provides insight
      into the locking scheme, that is, a heavily contended lock is indicative of
      a too coarse locking scheme.
      
      Lock hold-time is the duration the lock was held, this provides a reference for
      the wait-time numbers, so they can be put into perspective.
      
        1)
          lock
        2)
          ... do stuff ..
          unlock
        3)
      
      The time between 1 and 2 is the wait-time. The time between 2 and 3 is the
      hold-time.
      
      The lockdep held-lock tracking code is reused, because it already collects locks
      into meaningful groups (classes), and because it is an existing infrastructure
      for lock instrumentation.
      
      Currently lockdep tracks lock acquisition with two hooks:
      
        lock()
          lock_acquire()
          _lock()
      
       ... code protected by lock ...
      
        unlock()
          lock_release()
          _unlock()
      
      We need to extend this with two more hooks, in order to measure contention.
      
        lock_contended() - used to measure contention events
        lock_acquired()  - completion of the contention
      
      These are then placed the following way:
      
        lock()
          lock_acquire()
          if (!_try_lock())
            lock_contended()
            _lock()
            lock_acquired()
      
       ... do locked stuff ...
      
        unlock()
          lock_release()
          _unlock()
      
      (Note: the try_lock() 'trick' is used to avoid instrumenting all platform
             dependent lock primitive implementations.)
      
      It is also possible to toggle the two lockdep features at runtime using:
      
        /proc/sys/kernel/prove_locking
        /proc/sys/kernel/lock_stat
      
      (esp. turning off the O(n^2) prove_locking functionaliy can help)
      
      [akpm@linux-foundation.org: build fixes]
      [akpm@linux-foundation.org: nuke unneeded ifdefs]
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Acked-by: default avatarJason Baron <jbaron@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f20786ff
    • Peter Zijlstra's avatar
      lockdep: reduce the ifdeffery · 8e18257d
      Peter Zijlstra authored
      Move code around to get fewer but larger #ifdef sections.  Break some
      in-function #ifdefs out into their own functions.
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      8e18257d
    • Peter Zijlstra's avatar
      lockdep: sanitise CONFIG_PROVE_LOCKING · ca58abcb
      Peter Zijlstra authored
      Ensure that all of the lock dependency tracking code is under
      CONFIG_PROVE_LOCKING.  This allows us to use the held lock tracking code for
      other purposes.
      Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      Acked-by: default avatarIngo Molnar <mingo@elte.hu>
      Acked-by: default avatarJason Baron <jbaron@redhat.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ca58abcb
  19. 17 Jul, 2007 1 commit
    • Tejun Heo's avatar
      kallsyms: make KSYM_NAME_LEN include space for trailing '\0' · 9281acea
      Tejun Heo authored
      KSYM_NAME_LEN is peculiar in that it does not include the space for the
      trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating
      buffer.  This is nonsense and error-prone.  Moreover, when the caller
      forgets that it's very likely to subtly bite back by corrupting the stack
      because the last position of the buffer is always cleared to zero.
      
      This patch increments KSYM_NAME_LEN by one and updates code accordingly.
      
      * off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro
        is fixed.
      
      * Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together,
        MODULE_NAME_LEN was treated as if it didn't include space for the
        trailing '\0'.  Fix it.
      Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
      Acked-by: default avatarPaulo Marques <pmarques@grupopie.com>
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      9281acea
  20. 08 May, 2007 4 commits
  21. 23 Mar, 2007 1 commit