1. 03 Jun, 2009 8 commits
    • Steven Rostedt's avatar
      tracing: add annotation to what type of stack trace is recorded · 563af16c
      Steven Rostedt authored
      The current method of printing out a stack trace is to add a new line
      and print out the trace:
          yum-updatesd-3120  [002]   573.691303:
       => do_softirq
       => irq_exit
       => smp_apic_timer_interrupt
       => apic_timer_interrupt
      This looks a bit awkward, and if we have both stack and user stack traces
      running, it would be nice to have a title to tell them apart, although
      it is easy to tell by the output.
      This patch adds an annotation to the start of the stack traces:
                  init-1     [003]   929.304979: <stack trace>
       => user_path_at
       => vfs_fstatat
       => vfs_stat
       => sys_newstat
       => system_call_fastpath
                   cat-3459  [002]  1016.824040: <user stack trace>
       =>  <0000003aae6c0250>
       =>  <00007ffff4b06ae4>
       =>  <69636172742f6775>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Whitehouse's avatar
      tracing: fix multiple use of __print_flags and __print_symbolic · 56d8bd3f
      Steven Whitehouse authored
      Here is an updated patch to include the extra call to
      trace_seq_init() as requested. This is vs. the latest
      -tip tree and fixes the use of multiple __print_flags
      and __print_symbolic in a single tracer. Also tested
      to ensure its working now:
      mount.gfs2-2534  [000]   235.850587: gfs2_glock_queue: 8.7 glock 1:2 dequeue PR
      mount.gfs2-2534  [000]   235.850591: gfs2_demote_rq: 8.7 glock 1:0 demote EX to NL flags:DI
      mount.gfs2-2534  [000]   235.850591: gfs2_glock_queue: 8.7 glock 1:0 dequeue EX
      glock_workqueue-2529  [000]   235.850666: gfs2_glock_state_change: 8.7 glock 1:0 state EX => NL tgt:NL dmt:NL flags:lDpI
      glock_workqueue-2529  [000]   235.850672: gfs2_glock_put: 8.7 glock 1:0 state NL => IV flags:I
      Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
      LKML-Reference: <1244037123.29604.603.camel@localhost.localdomain>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • walimis's avatar
      tracing/events: fix output format of user stack · 048dc50c
      walimis authored
      According to "events/ftrace/user_stack/format", fix the output of
      user stack.
      before fix:
        sh-1073  [000]    31.137561:  <b7f274fe> <-  <0804e33c> <-  <080835c1>
      after fix:
        sh-1072  [000]    37.039329:
       =>  <b7f8a4fe>
       =>  <0804e33c>
       =>  <080835c1>
      Signed-off-by: default avatarwalimis <walimisdev@gmail.com>
      LKML-Reference: <1244016090-7814-3-git-send-email-walimisdev@gmail.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • walimis's avatar
      tracing/events: fix output format of kernel stack · f11b3f4e
      walimis authored
      According to "events/ftrace/kernel_stack/format", output format of
      kernel stack should use "=>" instead of "<=".
      The second problem is that we shouldn't skip the first entry in the stack,
      although it seems to be duplicated when used in the "function" tracer,
      but events also use it. If we skip the first one, we will drop the topmost
      entry of the stack.
      The last problem is that if the last entry is ULONG_MAX(0xffffffff), we should
      drop it, otherwise it will print a NULL name line.
      before fix:
            sh-1072  [000]   26.957239: sched_process_fork: parent sh:1072 child sh:1073
            sh-1072  [000]   26.957262:
       <= syscall_call
            sh-1072  [000]   26.957744: sched_switch: task sh:1072 [120] (R) ==> sh:1073 [120]
            sh-1072  [000]   26.957752:
       <= preempt_schedule
       <= wake_up_new_task
       <= do_fork
       <= sys_clone
       <= syscall_call
      After fix:
            sh-1075  [000]    39.791848: sched_process_fork: parent sh:1075  child sh:1076
            sh-1075  [000]    39.791871:
       => sys_clone
       => syscall_call
            sh-1075  [000]    39.792713: sched_switch: task sh:1075 [120] (R) ==> sh:1076 [120]
            sh-1075  [000]    39.792722:
       => schedule
       => preempt_schedule
       => wake_up_new_task
       => do_fork
       => sys_clone
       => syscall_call
      Signed-off-by: default avatarwalimis <walimisdev@gmail.com>
      LKML-Reference: <1244016090-7814-2-git-send-email-walimisdev@gmail.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • walimis's avatar
      tracing/trace_stack: fix the number of entries in the header · 083a63b4
      walimis authored
      The last entry in the stack_dump_trace is ULONG_MAX, which is not
      a valid entry, but max_stack_trace.nr_entries has accounted for it.
      So when printing the header, we should decrease it by one.
      Before fix, print as following, for example:
      	Depth    Size   Location    (53 entries)	<--- should be 52
      	-----    ----   --------
        0)     3264     108   update_wall_time+0x4d5/0x9a0
       51)       80      80   syscall_call+0x7/0xb
         it's correct.
      Signed-off-by: default avatarwalimis <walimisdev@gmail.com>
      LKML-Reference: <1244016090-7814-1-git-send-email-walimisdev@gmail.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Rostedt's avatar
      ring-buffer: discard timestamps that are at the start of the buffer · ea05b57c
      Steven Rostedt authored
      Every buffer page in the ring buffer includes its own time stamp.
      When an event is recorded to the ring buffer with a delta time greater
      than what can be held in the event header, a time stamp event is created.
      If the the create timestamp falls over to the next buffer page, it is
      redundant because the buffer page holds a full time stamp. This patch
      will try to discard the time stamp when it falls to the start of the
      next page.
      This change also fixes a issues with disarding events. If most events are
      discarded, timestamps will start to creep into the ring buffer. If we
      do not discard the timestamps then they can fill up the ring buffer over
      time and waste space.
      This change will keep time stamps from filling up over another page. If
      something is recorded in the buffer page, and the rest is filtered, then
      the time stamps can only fill up to the end of the page.
      [ Impact: prevent time stamps from filling ring buffer ]
      Reported-by: default avatarTim Bird <tim.bird@am.sony.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Rostedt's avatar
      ring-buffer: try to discard unneeded timestamps · edd813bf
      Steven Rostedt authored
      There are times that a race may happen that we add a timestamp in a
      nested write. This timestamp would just contain a zero delta and serves
      no purpose.
      Now that we have a way to discard events, this patch will try to discard
      the timestamp instead of just wasting the space in the ring buffer.
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Tim Bird's avatar
      ring-buffer: fix bug in ring_buffer_discard_commit · a2023556
      Tim Bird authored
      There's a bug in ring_buffer_discard_commit.  The wrong
      pointer is being compared in order to check if the event
      can be freed from the buffer rather than discarded
      (i.e. marked as PAD).
      I noticed this when I was working on duration filtering.
      The bug is not deadly - it just results in lots of wasted
      space in the buffer.  All filtered events are left in
      the buffer and marked as discarded, rather than being
      removed from the buffer to make space for other events.
      Unfortunately, when I fixed this bug, I got errors doing a
      filtered function trace.  Multiple TIME_EXTEND
      events pile up in the buffer, and trigger the
      following loop overage warning in rb_iter_peek():
      	if (RB_WARN_ON(cpu_buffer, ++nr_loops > 10))
      		return NULL;
      I'm not sure what the best way is to fix this. I don't
      know if I should extend the loop threshhold, or if I should
      make the test more complex (ignore TIME_EXTEND
      events), or just get rid of this loop check completely.
      Note that if I implement a workaround for this, then I
      see another problem from rb_advance_iter().  I haven't
      tracked that one down yet.
      In general, it seems like the case of removing filtered
      events has not been working properly, and so some assumptions
      about buffer invariant conditions need to be revisited.
      Here's the patch for the simple fix:
      Compare correct pointer for checking if an event can be
      freed rather than left as discarded in the buffer.
      Signed-off-by: default avatarTim Bird <tim.bird@am.sony.com>
      LKML-Reference: <4A25BE9E.5090909@am.sony.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
  2. 02 Jun, 2009 10 commits
    • Steven Rostedt's avatar
      ftrace: do not profile functions when disabled · 0f6ce3de
      Steven Rostedt authored
      A race was found that if one were to enable and disable the function
      profiler repeatedly, then the system can panic. This was because a profiled
      function may be preempted just before disabling interrupts. While
      the profiler is disabled and then reenabled, the preempted function
      could start again, and access the hash as it is being initialized.
      This just adds a check in the irq disabled part to check if the profiler
      is enabled, and if it is not then it will just exit.
      When the system is disabled, the profile_enabled variable is cleared
      before calling the unregistering of the function profiler. This
      unregistering calls stop machine which also acts as a synchronize schedule.
      [ Impact: fix panic in enabling/disabling function profiler ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Rostedt's avatar
      tracing: make trace pipe recognize latency format flag · 112f38a7
      Steven Rostedt authored
      The trace_pipe did not recognize the latency format flag and would produce
      different output than the trace file. The problem was partly due that
      the trace flags in the iterator was not set as well as the trace_pipe
      zeros out part of the iterator (including the flags) to be able to use
      the same routines as the trace file. trace_flags of the iterator should
      not cause any problems when not zeroed out by for trace_pipe.
      Reported-by: default avatarJohannes Berg <johannes@sipsolutions.net>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Rostedt's avatar
      tracing: remove redundant SOFTIRQ from softirq event traces · 1d080d6c
      Steven Rostedt authored
      After converting the softirq tracer to use te flags options, this
      caused a regression with the name. Since the flag was used directly
      it was printed out (i.e. HRTIMER_SOFTIRQ).
      This patch only shows the softirq name without the SOFTIRQ part.
      [ Impact: fix regression of output from softirq events ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Whitehouse's avatar
      tracing: add exports to use __print_symbolic and __print_flags from a module · ec081ddc
      Steven Whitehouse authored
      A patch to allow the use of __print_symbolic and __print_flags
      from a module. This allows the current GFS2 tracing patch to
      Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
      LKML-Reference: <1243868015.29604.542.camel@localhost.localdomain>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Li Zefan's avatar
      tracing/events: introduce __dynamic_array() · 7fcb7c47
      Li Zefan authored
      __string() is limited:
        - it's a char array, but we may want to define array with other types
        - a source string should be available, but we may just know the string size
      We introduce __dynamic_array() to break those limitations, and __string()
      becomes a wrapper of it. As a side effect, now __get_str() can be used
      in TP_fast_assign but not only TP_print.
      Take XFS for example, we have the string length in the dirent, but the
      string itself is not NULL-terminated, so __dynamic_array() can be used:
      	TP_PROTO(struct xfs_da_args *args),
      		__field(int, namelen)
      		__dynamic_array(char, name, args->namelen + 1)
      		char *name = __get_str(name);
      		if (args->namelen)
      			memcpy(name, args->name, args->namelen);
      		name[args->namelen] = '\0';
      		__entry->namelen = args->namelen;
      	TP_printk("name %.*s namelen %d",
      		  __entry->namelen ? __get_str(name) : NULL
      [ Impact: allow defining dynamic size arrays ]
      Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
      LKML-Reference: <4A2384D2.3080403@cn.fujitsu.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Li Zefan's avatar
      tracing/events: put TP_fast_assign into braces · a9c1c3ab
      Li Zefan authored
      Currently TP_fast_assign has a limitation that we can't define local
      variables in it.
      Here's one use case when we introduce __dynamic_array():
      	type *p = __get_dynamic_array(item);
      [ Impact: allow defining local variables in TP_fast_assign ]
      Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
      LKML-Reference: <4A2384B1.90100@cn.fujitsu.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Li Zefan's avatar
      tracing/events: fix a typo in __string() format output · 6e25db44
      Li Zefan authored
      "tsize" should be "\tsize". Also remove the space before "__str_loc".
       # cat tracing/events/irq/irq_handler_entry/format
              field:int irq;  offset:12;      size:4;
              field: __str_loc name;  offset:16;tsize:2;
       # cat tracing/events/irq/irq_handler_entry/format
              field:int irq;  offset:12;      size:4;
              field:__str_loc name;   offset:16;      size:2;
      [ Impact: standardize __string field description in events format file ]
      Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Rostedt's avatar
      tracing: combine the default tracers into one config · 897f17a6
      Steven Rostedt authored
      Both event tracer and sched switch plugin are selected by default
      by all generic tracers. But if no generic tracer is enabled, their options
      appear. But ether one of them will select the other, thus it only
      makes sense to have the default tracers be selected by one option.
      [ Impact: clean up kconfig menu ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Rostedt's avatar
      tracing: fix config options to not show when automatically selected · 5e0a0939
      Steven Rostedt authored
      There are two options that are selected by all tracers, but we want
      to have those options available when no tracer is selected. These are
       The event tracer and sched switch tracer.
      The are enabled by all tracers, but if a tracer is not selected we want
      the options to appear. All tracers including them select TRACING.
      Thus what we would like to do is:
        config EVENT_TRACER
      	bool "prompt"
      	depends on TRACING
      	select TRACING
      But that gives us a bug in the kbuild system since we just created a
      circular dependency. We only want the prompt to show when TRACING is off.
      This patch adds GENERIC_TRACER that all tracers will select instead of
      TRACING. The two options (sched switch and event tracer) will select
      TRACING directly and depend on !GENERIC_TRACER. This solves the cicular
      [ Impact: hide options that are selected by default ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    • Steven Rostedt's avatar
      ftrace: add kernel command line function filtering · 2af15d6a
      Steven Rostedt authored
      When using ftrace=function on the command line to trace functions
      on boot up, one can not filter out functions that are commonly called.
      This patch adds two new ftrace command line commands.
      Where function-list is a comma separated list of functions to filter.
      The ftrace_notrace will make the functions listed not be included
      in the function tracing, and ftrace_filter will only trace the functions
      These two act the same as the debugfs/tracing/set_ftrace_notrace and
      debugfs/tracing/set_ftrace_filter respectively.
      The simple glob expressions that are allowed by the filter files can also
      be used by the command line interface.
      Will not trace any function that starts with rcu, ends with lock, or has
      the word spin in it.
      Note, if the self tests are enabled, they may interfere with the filtering
      set by the command lines.
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
  3. 27 May, 2009 2 commits
    • Zhaolei's avatar
      ftrace: don't convert function's local variable name in macro · f2aebaee
      Zhaolei authored
      "call" is an argument of macro, but it is also used as a local
      variable name of function in macro.
      We should keep this local variable name distinct from any
      CPP macro parameter name if both are in the same macro scope,
      although it hasn't caused any problem yet.
      [ Impact: robustify macro ]
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Heiko Carstens's avatar
      trace: disable preemption before taking raw spinlocks · 5b6045a9
      Heiko Carstens authored
      s390 code uses smp_processor_id() in __raw_spin_lock() code which
      reveals that a (raw) spinlock is taken without preemption disabled.
      This can potentially deadlock.
      To fix this explicitly disable and enable preemption.
      BUG: using smp_processor_id() in preemptible [00000000] code: cat/2278
      caller is trace_find_cmdline+0x40/0xfc
      CPU: 0 Not tainted 2.6.30-rc7-dirty #39
      Process cat (pid: 2278, task: 000000003faedb68, ksp: 000000003b33b988)
      000000003b33b988 000000003b33bae0 0000000000000002 0000000000000000
             000000003b33bb80 000000003b33baf8 000000003b33baf8 00000000000175d6
             0000000000000001 000000003b33b988 000000003f9b0000 000000000000000b
             000000000000000c 000000003b33bb40 000000003b33bae0 0000000000000000
             0000000000000000 00000000000175d6 000000003b33bae0 000000003b33bb28
      Call Trace:
      ([<00000000000174b2>] show_trace+0x112/0x170)
       [<0000000000017582>] show_stack+0x72/0x100
       [<0000000000441538>] dump_stack+0xc8/0xd8
       [<000000000025c350>] debug_smp_processor_id+0x114/0x130
       [<00000000000bf0e4>] trace_find_cmdline+0x40/0xfc
       [<00000000000c35d4>] trace_print_context+0x58/0xac
       [<00000000000bb676>] print_trace_line+0x416/0x470
       [<00000000000bc8fe>] s_show+0x4e/0x428
       [<000000000013834e>] seq_read+0x36a/0x5d4
       [<0000000000112a78>] vfs_read+0xc8/0x174
       [<0000000000112c58>] SyS_read+0x74/0xc4
       [<000000000002c7ae>] sysc_noemu+0x10/0x16
       [<000002000012436c>] 0x2000012436c
      1 lock held by cat/2278:
       #0:  (&p->lock){+.+.+.}, at: [<0000000000138056>] seq_read+0x72/0x5d4
      [ Impact: fix preempt-unsafe raw spinlock ]
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
  4. 26 May, 2009 8 commits
    • Steven Rostedt's avatar
      tracing: convert irq events to use __print_symbolic · c2adae09
      Steven Rostedt authored
      The recording of the names at trace time is inefficient. This patch
      implements the softirq event recording to only record the vector
      and then use the __print_symbolic interface to print out the names.
      [ Impact: faster recording of softirq events ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Steven Rostedt's avatar
      tracing: add __print_symbolic to trace events · 0f4fc29d
      Steven Rostedt authored
      This patch adds __print_symbolic which is similar to __print_flags but
      works for an enumeration type instead. That is, there is only a one to one
      mapping between the values and the symbols. When a match is made, then
      it is printed, otherwise the hex value is outputed.
      [ Impact: add interface for showing symbol names in events ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Steven Rostedt's avatar
      tracing: add flag output for kmem events · 62ba180e
      Steven Rostedt authored
      This patch changes the output for gfp_flags from being a simple hex value
      to the actual names.
        gfp_flags=GFP_ATOMIC  instead of gfp_flags=00000020
      And even
        gfp_flags=GFP_KERNEL instead of gfp_flags=000000d0
      (Thanks to Frederic Weisbecker for pointing out that the first version
       had a bad order of GFP masks)
      [ Impact: more human readable output from tracer ]
      Acked-by: default avatarEduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Steven Rostedt's avatar
      tracing: add previous task state info to sched switch event · 937cdb9d
      Steven Rostedt authored
      It is useful to see the state of a task that is being switched out.
      This patch adds the output of the state of the previous task in
      the context switch event.
      [ Impact: see state of switched out task in context switch ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Steven Rostedt's avatar
      tracing: add __print_flags for events · be74b73a
      Steven Rostedt authored
      Developers have been asking for the ability in the ftrace event tracer
      to display names of bits in a flags variable.
      Instead of printing out c2, it would be easier to read FOO|BAR|GOO,
      assuming that FOO is bit 1, BAR is bit 6 and GOO is bit 7.
      Some examples where this would be useful are the state flags in a context
      switch, kmalloc flags, and even permision flags in accessing files.
        v2 changes include:
        Frederic Weisbecker's idea of using a mask instead of bits,
        thus we can output GFP_KERNEL instead of GPF_WAIT|GFP_IO|GFP_FS.
        Li Zefan's idea of allowing the caller of __print_flags to add their
        own delimiter (or no delimiter) where we can get for file permissions
        rwx instead of r|w|x.
        v3 changes:
         Christoph Hellwig's idea of using an array instead of va_args.
      [ Impact: better displaying of flags in trace output ]
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Zhaolei's avatar
      ftrace: clean up of using ftrace_event_enable_disable() · 0e907c99
      Zhaolei authored
      Always use ftrace_event_enable_disable() to enable/disable an event
      so that we can factorize out the event toggling code.
      [ Impact: factorize and cleanup event tracing code ]
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Tom Zanussi <tzanussi@gmail.com>
      LKML-Reference: <4A14FDFE.2080402@cn.fujitsu.com>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Zhaolei's avatar
      ftrace: Add task_comm support for trace_event · b11c53e1
      Zhaolei authored
      If we enable a trace event alone without any tracer running (such as
      function tracer, sched switch tracer, etc...) it can't output enough
      task command information.
      We need to use the tracing_{start/stop}_cmdline_record() helpers
      which are designed to keep track of cmdlines for any tasks that
      were scheduled during the tracing.
      Before this patch:
       # echo 1 > debugfs/tracing/events/sched/sched_switch/enable
       # cat debugfs/tracing/trace
       # tracer: nop
       #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
       #              | |       |          |         |
                  <...>-2289  [000] 526276.724790: sched_switch: task bash:2289 [120] ==> sshd:2287 [120]
                  <...>-2287  [000] 526276.725231: sched_switch: task sshd:2287 [120] ==> bash:2289 [120]
                  <...>-2289  [000] 526276.725452: sched_switch: task bash:2289 [120] ==> sshd:2287 [120]
                  <...>-2287  [000] 526276.727181: sched_switch: task sshd:2287 [120] ==> swapper:0 [140]
                 <idle>-0     [000] 526277.032734: sched_switch: task swapper:0 [140] ==> events/0:5 [115]
                  <...>-5     [000] 526277.032782: sched_switch: task events/0:5 [115] ==> swapper:0 [140]
      After this patch:
       # tracer: nop
       #           TASK-PID    CPU#    TIMESTAMP  FUNCTION
       #              | |       |          |         |
                   bash-2269  [000] 527347.989229: sched_switch: task bash:2269 [120] ==> sshd:2267 [120]
                   sshd-2267  [000] 527347.990960: sched_switch: task sshd:2267 [120] ==> bash:2269 [120]
                   bash-2269  [000] 527347.991143: sched_switch: task bash:2269 [120] ==> sshd:2267 [120]
                   sshd-2267  [000] 527347.992959: sched_switch: task sshd:2267 [120] ==> swapper:0 [140]
                 <idle>-0     [000] 527348.531989: sched_switch: task swapper:0 [140] ==> events/0:5 [115]
               events/0-5     [000] 527348.532115: sched_switch: task events/0:5 [115] ==> swapper:0 [140]
      v1->v2: Update Kconfig to select CONTEXT_SWITCH_TRACER in
      v2->v3: v2 can solve problem that was caused by config EVENT_TRACING
              alone, but when CONFIG_FTRACE is off and CONFIG_TRACING is
              selected by other config, compile fail happened again.
              This version solves it.
      [ Impact: fix incomplete output of event tracing ]
      Signed-off-by: default avatarZhao Lei <zhaolei@cn.fujitsu.com>
      Cc: Tom Zanussi <tzanussi@gmail.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      LKML-Reference: <4A14FDFE.2080402@cn.fujitsu.com>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Pekka Enberg's avatar
      kmemtrace: fix kernel parameter documentation · 29fcefba
      Pekka Enberg authored
      The kmemtrace.enable kernel parameter no longer works. To enable
      kmemtrace at boot-time, you must pass "ftrace=kmemtrace" instead.
      [ Impact: remove obsolete kernel parameter documentation ]
      Cc: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
      Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
      LKML-Reference: <alpine.DEB.2.00.0905241112190.10296@rocky>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
  5. 25 May, 2009 2 commits
    • Li Zefan's avatar
      tracing/events: change the type of __str_loc_item to unsigned short · b0aae68c
      Li Zefan authored
      When defining a dynamic size string, we add __str_loc_##item to the
      trace entry, and it stores the location of the actual string in
      'unsigned short' should be sufficient to store this information, thus
      we save 2 bytes per dyn-size string in the ring buffer.
      [ Impact: reduce memory occupied by dyn-size strings in ring buffer ]
      Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      LKML-Reference: <4A14EDB6.2050507@cn.fujitsu.com>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
    • Lai Jiangshan's avatar
      tracing: add trace_event_read_lock() · 4f535968
      Lai Jiangshan authored
      I found that there is nothing to protect event_hash in
      ftrace_find_event(). Rcu protects the event hashlist
      but not the event itself while we use it after its extraction
      through ftrace_find_event().
      This lack of a proper locking in this spot opens a race
      window between any event dereferencing and module removal.
      --Task A--
      print_trace_line(trace) {
        event = find_ftrace_event(trace)
      --Task B--
      trace_module_remove_events(mod) {
        list_trace_events_module(ev, mod) {
          unregister_ftrace_event(ev->event) {
      |--> module removed, the event has been dropped
      --Task A--
        event->print(trace); // Dereferencing freed memory
      If the event retrieved belongs to a module and this module
      is concurrently removed, we may end up dereferencing a data
      from a freed module.
      RCU could solve this, but it would add latency to the kernel and
      forbid tracers output callbacks to call any sleepable code.
      So this fix converts 'trace_event_mutex' to a read/write semaphore,
      and adds trace_event_read_lock() to protect ftrace_find_event().
      [ Impact: fix possible freed memory dereference in ftrace ]
      Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
      Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      LKML-Reference: <4A114806.7090302@cn.fujitsu.com>
      Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
  6. 20 May, 2009 1 commit
  7. 19 May, 2009 2 commits
    • Stefan Raspl's avatar
      blktrace: remove debugfs entries on bad path · fd51d251
      Stefan Raspl authored
      debugfs directory entries for devices are not removed on some
      of the failure pathes in do_blk_trace_setup().
      One way to reproduce is to start blktrace on multiple devices
      with insufficient Vmalloc space: Devices will fail with
      a message like this:
      	BLKTRACESETUP(2) /dev/sdu failed: 5/Input/output error
      If so, the respective entries in debugfs
      (e.g. /sys/kernel/debug/block/sdu) will remain and subsequent
      attempts to start blktrace on the respective devices will not
      succeed due to existing directories.
      [ Impact: fix /debug/tracing file cleanup corner case ]
      Signed-off-by: default avatarStefan Raspl <stefan.raspl@linux.vnet.ibm.com>
      Acked-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
      Cc: Li Zefan <lizf@cn.fujitsu.com>
      Cc: schwidefsky@de.ibm.com
      Cc: heiko.carstens@de.ibm.com
      LKML-Reference: <4A1266CC.5040801@linux.vnet.ibm.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    • Li Zefan's avatar
      tracing/events: Documentation updates · 143c145e
      Li Zefan authored
      - fix some typos
      - document the difference between '>' and '>>'
      - document the 'enable' toggle
      - remove section "Defining an event-enabled tracepoint", since it's
        out-dated and sample/trace_events/ already serves this purpose.
      v2: add "Updated by Li Zefan"
      [ Impact: make documentation up-to-date ]
      Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: "Theodore Ts'o" <tytso@mit.edu>
      LKML-Reference: <4A125503.5060406@cn.fujitsu.com>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
  8. 18 May, 2009 2 commits
  9. 16 May, 2009 1 commit
  10. 15 May, 2009 4 commits