116444a8aSArnaldo Carvalho de Melo# 216444a8aSArnaldo Carvalho de Melo# Architectures that offer an FTRACE implementation should select HAVE_FTRACE: 316444a8aSArnaldo Carvalho de Melo# 416444a8aSArnaldo Carvalho de Meloconfig HAVE_FTRACE 516444a8aSArnaldo Carvalho de Melo bool 6bc0c38d1SSteven Rostedt 7352ad25aSSteven Rostedtconfig TRACER_MAX_TRACE 8352ad25aSSteven Rostedt bool 9352ad25aSSteven Rostedt 10bc0c38d1SSteven Rostedtconfig TRACING 11bc0c38d1SSteven Rostedt bool 12bc0c38d1SSteven Rostedt select DEBUG_FS 13bc0c38d1SSteven Rostedt 141b29b018SSteven Rostedtconfig FTRACE 151b29b018SSteven Rostedt bool "Kernel Function Tracer" 161b29b018SSteven Rostedt depends on DEBUG_KERNEL && HAVE_FTRACE 171b29b018SSteven Rostedt select FRAME_POINTER 181b29b018SSteven Rostedt select TRACING 1935e8e302SSteven Rostedt select CONTEXT_SWITCH_TRACER 201b29b018SSteven Rostedt help 211b29b018SSteven Rostedt Enable the kernel to trace every kernel function. This is done 221b29b018SSteven Rostedt by using a compiler feature to insert a small, 5-byte No-Operation 231b29b018SSteven Rostedt instruction to the beginning of every kernel function, which NOP 241b29b018SSteven Rostedt sequence is then dynamically patched into a tracer call when 251b29b018SSteven Rostedt tracing is enabled by the administrator. If it's runtime disabled 261b29b018SSteven Rostedt (the bootup default), then the overhead of the instructions is very 271b29b018SSteven Rostedt small and not measurable even in micro-benchmarks. 2835e8e302SSteven Rostedt 29*81d68a96SSteven Rostedtconfig IRQSOFF_TRACER 30*81d68a96SSteven Rostedt bool "Interrupts-off Latency Tracer" 31*81d68a96SSteven Rostedt default n 32*81d68a96SSteven Rostedt depends on TRACE_IRQFLAGS_SUPPORT 33*81d68a96SSteven Rostedt depends on GENERIC_TIME 34*81d68a96SSteven Rostedt select TRACE_IRQFLAGS 35*81d68a96SSteven Rostedt select TRACING 36*81d68a96SSteven Rostedt select TRACER_MAX_TRACE 37*81d68a96SSteven Rostedt help 38*81d68a96SSteven Rostedt This option measures the time spent in irqs-off critical 39*81d68a96SSteven Rostedt sections, with microsecond accuracy. 40*81d68a96SSteven Rostedt 41*81d68a96SSteven Rostedt The default measurement method is a maximum search, which is 42*81d68a96SSteven Rostedt disabled by default and can be runtime (re-)started 43*81d68a96SSteven Rostedt via: 44*81d68a96SSteven Rostedt 45*81d68a96SSteven Rostedt echo 0 > /debugfs/tracing/tracing_max_latency 46*81d68a96SSteven Rostedt 47352ad25aSSteven Rostedtconfig SCHED_TRACER 48352ad25aSSteven Rostedt bool "Scheduling Latency Tracer" 49352ad25aSSteven Rostedt depends on DEBUG_KERNEL 50352ad25aSSteven Rostedt select TRACING 51352ad25aSSteven Rostedt select CONTEXT_SWITCH_TRACER 52352ad25aSSteven Rostedt select TRACER_MAX_TRACE 53352ad25aSSteven Rostedt help 54352ad25aSSteven Rostedt This tracer tracks the latency of the highest priority task 55352ad25aSSteven Rostedt to be scheduled in, starting from the point it has woken up. 56352ad25aSSteven Rostedt 5735e8e302SSteven Rostedtconfig CONTEXT_SWITCH_TRACER 5835e8e302SSteven Rostedt bool "Trace process context switches" 5935e8e302SSteven Rostedt depends on DEBUG_KERNEL 6035e8e302SSteven Rostedt select TRACING 6135e8e302SSteven Rostedt select MARKERS 6235e8e302SSteven Rostedt help 6335e8e302SSteven Rostedt This tracer gets called from the context switch and records 6435e8e302SSteven Rostedt all switching of tasks. 6535e8e302SSteven Rostedt 66