From bac429f037f1a51a74d62bad6d1518c3be065df3 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 20 Mar 2009 12:50:56 -0400 Subject: tracing: add function profiler Impact: new profiling feature This patch adds a function profiler. In debugfs/tracing/ two new files are created. function_profile_enabled - to enable or disable profiling trace_stat/functions - the profiled functions. For example: echo 1 > /debugfs/tracing/function_profile_enabled ./hackbench 50 echo 0 > /debugfs/tracing/function_profile_enabled yields: cat /debugfs/tracing/trace_stat/functions Function Hit -------- --- _spin_lock 10106442 _spin_unlock 10097492 kfree 6013704 _spin_unlock_irqrestore 4423941 _spin_lock_irqsave 4406825 __phys_addr 4181686 __slab_free 4038222 dput 4030130 path_put 4023387 unroll_tree_refs 4019532 [...] The most hit functions are listed first. Functions that are not hit are not listed. This feature depends on and uses dynamic function tracing. When the function profiling is disabled, no overhead occurs. But it still takes up around 300KB to hold the data, thus it is not recomended to keep it enabled for systems low on memory. When a '1' is echoed into the function_profile_enabled file, the counters for is function is reset back to zero. Thus you can see what functions are hit most by different programs. Signed-off-by: Steven Rostedt --- kernel/trace/Kconfig | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'kernel/trace/Kconfig') diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 8a4d729..95e9ad5 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -105,6 +105,7 @@ config FUNCTION_GRAPH_TRACER This is done by setting the current return address on the current task structure into a stack of calls. + config IRQSOFF_TRACER bool "Interrupts-off Latency Tracer" default n @@ -376,6 +377,24 @@ config DYNAMIC_FTRACE were made. If so, it runs stop_machine (stops all CPUS) and modifies the code to jump over the call to ftrace. +config FUNCTION_PROFILER + bool "Kernel function profiler" + depends on DYNAMIC_FTRACE + default n + help + This option enables the kernel function profiler. When the dynamic + function tracing is enabled, a counter is added into the function + records used by the dynamic function tracer. A file is created in + debugfs called function_profile_enabled which defaults to zero. + When a 1 is echoed into this file profiling begins, and when a + zero is entered, profiling stops. A file in the trace_stats + directory called functions, that show the list of functions that + have been hit and their counters. + + This takes up around 320K more memory. + + If in doubt, say N + config FTRACE_MCOUNT_RECORD def_bool y depends on DYNAMIC_FTRACE -- cgit v1.1