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authorTim Bird <tim.bird@am.sony.com>2010-02-25 15:36:43 -0800
committerSteven Rostedt <rostedt@goodmis.org>2010-03-05 21:20:57 -0500
commit0e95017355dcf43031da6d0e360a748717e56df1 (patch)
tree829989bfb494e8d2d773d9dc1bc014b7f28d3bed /arch/arm/mach-footbridge/include/mach/debug-macro.S
parent1acaa1b2d9b5904c9cce06122990a2d71046ce16 (diff)
function-graph: Add tracing_thresh support to function_graph tracer
Add support for tracing_thresh to the function_graph tracer. This version of this feature isolates the checks into new entry and return functions, to avoid adding more conditional code into the main function_graph paths. When the tracing_thresh is set and the function graph tracer is enabled, only the functions that took longer than the time in microseconds that was set in tracing_thresh are recorded. To do this efficiently, only the function exits are recorded: [tracing]# echo 100 > tracing_thresh [tracing]# echo function_graph > current_tracer [tracing]# cat trace # tracer: function_graph # # CPU DURATION FUNCTION CALLS # | | | | | | | 1) ! 119.214 us | } /* smp_apic_timer_interrupt */ 1) <========== | 0) ! 101.527 us | } /* __rcu_process_callbacks */ 0) ! 126.461 us | } /* rcu_process_callbacks */ 0) ! 145.111 us | } /* __do_softirq */ 0) ! 149.667 us | } /* do_softirq */ 0) ! 168.817 us | } /* irq_exit */ 0) ! 248.254 us | } /* smp_apic_timer_interrupt */ Also, add support for specifying tracing_thresh on the kernel command line. When used like so: "tracing_thresh=200 ftrace=function_graph" this can be used to analyse system startup. It is important to disable tracing soon after boot, in order to avoid losing the trace data. Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Tim Bird <tim.bird@am.sony.com> LKML-Reference: <4B87098B.4040308@am.sony.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch/arm/mach-footbridge/include/mach/debug-macro.S')
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