linux/kernel/trace/trace_functions_graph.c, branch v3.8

tracing: Cache comms only after an event occurred

2012-10-31T20:45:31Z

Whenever an event is registered, the comm of tasks are saved at every task switch instead of saving them at every event. But if an event isn't executed much, the comm cache will be filled up by tasks that did not record the event and you lose out on the comms that did. Here's an example, if you enable the following events: echo 1 > /debug/tracing/events/kvm/kvm_cr/enable echo 1 > /debug/tracing/events/net/net_dev_xmit/enable Note, there's no kvm running on this machine so the first event will never be triggered, but because it is enabled, the storing of comms will continue. If we now disable the network event: echo 0 > /debug/tracing/events/net/net_dev_xmit/enable and look at the trace: cat /debug/tracing/trace sshd-2672 [001] ..s2 375.731616: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s1 375.731617: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s2 375.859356: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s1 375.859357: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s2 375.947351: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s1 375.947352: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s2 376.035383: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s1 376.035383: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 sshd-2672 [001] ..s2 377.563806: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=226 rc=0 sshd-2672 [001] ..s1 377.563807: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=226 rc=0 sshd-2672 [001] ..s2 377.563834: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6be0 len=114 rc=0 sshd-2672 [001] ..s1 377.563842: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6be0 len=114 rc=0 We see that process 2672 which triggered the events has the comm "sshd". But if we run hackbench for a bit and look again: cat /debug/tracing/trace <...>-2672 [001] ..s2 375.731616: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s1 375.731617: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s2 375.859356: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s1 375.859357: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s2 375.947351: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s1 375.947352: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s2 376.035383: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s1 376.035383: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=242 rc=0 <...>-2672 [001] ..s2 377.563806: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6de0 len=226 rc=0 <...>-2672 [001] ..s1 377.563807: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6de0 len=226 rc=0 <...>-2672 [001] ..s2 377.563834: net_dev_xmit: dev=eth0 skbaddr=ffff88005cbb6be0 len=114 rc=0 <...>-2672 [001] ..s1 377.563842: net_dev_xmit: dev=br0 skbaddr=ffff88005cbb6be0 len=114 rc=0 The stored "sshd" comm has been flushed out and we get a useless "<...>". But by only storing comms after a trace event occurred, we can run hackbench all day and still get the same output. Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Steven Rostedt

tracing: Allow tracers to start at core initcall

2012-10-31T20:45:24Z

There's times during debugging that it is helpful to see traces of early boot functions. But the tracers are initialized at device_initcall() which is quite late during the boot process. Setting the kernel command line parameter ftrace=function will not show anything until the function tracer is initialized. This prevents being able to trace functions before device_initcall(). There's no reason that the tracers need to be initialized so late in the boot process. Move them up to core_initcall() as they still need to come after early_initcall() which initializes the tracing buffers. Cc: Thomas Gleixner Signed-off-by: Steven Rostedt

ftrace: Do not test frame pointers if -mfentry is used

2012-08-23T15:25:29Z

The function graph has a test to check if the frame pointer is corrupted, which can happen with various options of gcc with mcount. But this is not an issue with -mfentry as -mfentry does not need nor use frame pointers for function graph tracing. Link: http://lkml.kernel.org/r/20120807194059.773895870@goodmis.org Acked-by: H. Peter Anvin Acked-by: Ingo Molnar Cc: Andi Kleen Signed-off-by: Steven Rostedt

tracing: Remove NR_CPUS array from trace_iterator

2012-06-28T17:52:15Z

Replace the NR_CPUS array of buffer_iter from the trace_iterator with an allocated array. This will just create an array of possible CPUS instead of the max number specified. The use of NR_CPUS in that array caused allocation failures for machines that were tight on memory. This did not cause any failures to the system itself (no crashes), but caused unnecessary failures for reading the trace files. Added a helper function called 'trace_buffer_iter()' that returns the buffer_iter item or NULL if it is not defined or the array was not allocated. Some routines do not require the array (tracing_open_pipe() for one). Reported-by: Dave Jones Signed-off-by: Steven Rostedt

tracing: Still trace filtered irq functions when irq trace is disabled

2011-07-08T02:26:27Z

If a function is set to be traced by the set_graph_function, but the option funcgraph-irqs is zero, and the traced function happens to be called from a interrupt, it will not be traced. The point of funcgraph-irqs is to not trace interrupts when we are preempted by an irq, not to not trace functions we want to trace that happen to be *in* a irq. Luckily the current->trace_recursion element is perfect to add a flag to help us be able to trace functions within an interrupt even when we are not tracing interrupts that preempt the trace. Reported-by: Heiko Carstens Tested-by: Heiko Carstens Signed-off-by: Steven Rostedt

tracing, function_graph: Add context-info support for function_graph tracer

2011-06-15T02:48:49Z

The function_graph tracer does not follow global context-info option. Adding TRACE_ITER_CONTEXT_INFO trace_flags check to enable it. With following commands: # echo function_graph > ./current_tracer # echo 0 > options/context-info # cat trace This is what it looked like before: # tracer: function_graph # # TIME CPU DURATION FUNCTION CALLS # | | | | | | | | 1) 0.079 us | } /* __vma_link_rb */ 1) 0.056 us | copy_page_range(); 1) | security_vm_enough_memory() { ... This is what it looks like now: # tracer: function_graph # } /* update_ts_time_stats */ timekeeping_max_deferment(); ... Signed-off-by: Jiri Olsa Link: http://lkml.kernel.org/r/1307113131-10045-6-git-send-email-jolsa@redhat.com Signed-off-by: Steven Rostedt

tracing, function_graph: Remove lock-depth from latency trace

2011-06-15T02:48:49Z

The lock_depth was removed in commit e6e1e25 tracing: Remove lock_depth from event entry Removing the lock_depth info from function_graph latency header. With following commands: # echo function_graph > ./current_tracer # echo 1 > options/latency-format # cat trace This is what it looked like before: # tracer: function_graph # # function_graph latency trace v1.1.5 on 3.0.0-rc1-tip+ # -------------------------------------------------------------------- # latency: 0 us, #59756/311298, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2) # ----------------- # | task: -0 (uid:0 nice:0 policy:0 rt_prio:0) # ----------------- # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> lock-depth # |||| / # CPU||||| DURATION FUNCTION CALLS # | ||||| | | | | | | 0) .... 0.068 us | } /* __rcu_read_unlock */ ... This is what it looks like now: # tracer: function_graph # # function_graph latency trace v1.1.5 on 3.0.0-rc1-tip+ # -------------------------------------------------------------------- # latency: 0 us, #59747/1744610, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:2) # ----------------- # | task: -0 (uid:0 nice:0 policy:0 rt_prio:0) # ----------------- # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / # CPU|||| DURATION FUNCTION CALLS # | |||| | | | | | | 0) ..s. 1.641 us | } /* __rcu_process_callbacks */ ... Signed-off-by: Jiri Olsa Link: http://lkml.kernel.org/r/1307113131-10045-5-git-send-email-jolsa@redhat.com Signed-off-by: Steven Rostedt

tracing, function_graph: Merge overhead and duration display functions

2011-06-15T02:48:47Z

Functions print_graph_overhead() and print_graph_duration() displays data for one field - DURATION. I merged them into single function print_graph_duration(), and added a way to display the empty parts of the field. This way the print_graph_irq() function can use this column to display the IRQ signs if needed and the DURATION field details stays inside the print_graph_duration() function. Signed-off-by: Jiri Olsa Link: http://lkml.kernel.org/r/1307113131-10045-3-git-send-email-jolsa@redhat.com Signed-off-by: Steven Rostedt

tracing, function_graph: Remove dependency of abstime and duration fields on latency

2011-06-15T02:48:47Z

The display of absolute time and duration fields is based on the latency field. This was added during the irqsoff/wakeup tracers graph support changes. It's causing confusion in what fields will be displayed for the function_graph tracer itself. So I'm removing this depency, and adding absolute time and duration fields to the preemptirqsoff preemptoff irqsoff wakeup tracers. With following commands: # echo function_graph > ./current_tracer # cat trace This is what it looked like before: # tracer: function_graph # # TIME CPU DURATION FUNCTION CALLS # | | | | | | | | 0) 0.068 us | } /* page_add_file_rmap */ 0) | _raw_spin_unlock() { ... This is what it looks like now: # tracer: function_graph # # CPU DURATION FUNCTION CALLS # | | | | | | | 0) 0.068 us | } /* add_preempt_count */ 0) 0.993 us | } /* vfsmount_lock_local_lock */ ... For preemptirqsoff preemptoff irqsoff wakeup tracers, this is what it looked like before: SNIP # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> lock-depth # |||| / # CPU TASK/PID ||||| DURATION FUNCTION CALLS # | | | ||||| | | | | | | 1) -0 | d..1 0.000 us | acpi_idle_enter_simple(); ... This is what it looks like now: SNIP # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / # TIME CPU TASK/PID |||| DURATION FUNCTION CALLS # | | | | |||| | | | | | | 19.847735 | 1) -0 | d..1 0.000 us | acpi_idle_enter_simple(); ... Signed-off-by: Jiri Olsa Link: http://lkml.kernel.org/r/1307113131-10045-2-git-send-email-jolsa@redhat.com Signed-off-by: Steven Rostedt

Fix common misspellings

2011-03-31T14:26:23Z

Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi