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![Tom Zanussi](/assets/img/avatar_default.png)
This patch adds per-event filtering to the event tracing subsystem. It adds a 'filter' debugfs file to each event directory. This file can be written to to set filters; reading from it will display the current set of filters set for that event. Basically, any field listed in the 'format' file for an event can be filtered on (including strings, but not yet other array types) using either matching ('==') or non-matching ('!=') 'predicates'. A 'predicate' can be either a single expression: # echo pid != 0 > filter # cat filter pid != 0 or a compound expression of up to 8 sub-expressions combined using '&&' or '||': # echo comm == Xorg > filter # echo "&& sig != 29" > filter # cat filter comm == Xorg && sig != 29 Only events having field values matching an expression will be available in the trace output; non-matching events are discarded. Note that a compound expression is built up by echoing each sub-expression separately - it's not the most efficient way to do things, but it keeps the parser simple and assumes that compound expressions will be relatively uncommon. In any case, a subsequent patch introducing a way to set filters for entire subsystems should mitigate any need to do this for lots of events. Setting a filter without an '&&' or '||' clears the previous filter completely and sets the filter to the new expression: # cat filter comm == Xorg && sig != 29 # echo comm != Xorg # cat filter comm != Xorg To clear a filter, echo 0 to the filter file: # echo 0 > filter # cat filter none The limit of 8 predicates for a compound expression is arbitrary - for efficiency, it's implemented as an array of pointers to predicates, and 8 seemed more than enough for any filter... Signed-off-by: Tom Zanussi <tzanussi@gmail.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <1237710665.7703.48.camel@charm-linux> Signed-off-by: Ingo Molnar <mingo@elte.hu>
50 lines
1.8 KiB
Makefile
50 lines
1.8 KiB
Makefile
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# Do not instrument the tracer itself:
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ifdef CONFIG_FUNCTION_TRACER
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ORIG_CFLAGS := $(KBUILD_CFLAGS)
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KBUILD_CFLAGS = $(subst -pg,,$(ORIG_CFLAGS))
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# selftest needs instrumentation
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CFLAGS_trace_selftest_dynamic.o = -pg
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obj-y += trace_selftest_dynamic.o
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endif
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# If unlikely tracing is enabled, do not trace these files
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ifdef CONFIG_TRACING_BRANCHES
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KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
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endif
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obj-$(CONFIG_FUNCTION_TRACER) += libftrace.o
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obj-$(CONFIG_RING_BUFFER) += ring_buffer.o
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obj-$(CONFIG_TRACING) += trace.o
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obj-$(CONFIG_TRACING) += trace_clock.o
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obj-$(CONFIG_TRACING) += trace_output.o
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obj-$(CONFIG_TRACING) += trace_stat.o
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obj-$(CONFIG_TRACING) += trace_printk.o
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obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
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obj-$(CONFIG_SYSPROF_TRACER) += trace_sysprof.o
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obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o
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obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
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obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
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obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
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obj-$(CONFIG_NOP_TRACER) += trace_nop.o
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obj-$(CONFIG_STACK_TRACER) += trace_stack.o
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obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
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obj-$(CONFIG_BOOT_TRACER) += trace_boot.o
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obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += trace_functions_graph.o
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obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o
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obj-$(CONFIG_HW_BRANCH_TRACER) += trace_hw_branches.o
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obj-$(CONFIG_POWER_TRACER) += trace_power.o
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obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
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obj-$(CONFIG_WORKQUEUE_TRACER) += trace_workqueue.o
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obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
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obj-$(CONFIG_EVENT_TRACER) += trace_events.o
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obj-$(CONFIG_EVENT_TRACER) += events.o
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obj-$(CONFIG_EVENT_TRACER) += trace_export.o
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obj-$(CONFIG_FTRACE_SYSCALLS) += trace_syscalls.o
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obj-$(CONFIG_EVENT_PROFILE) += trace_event_profile.o
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obj-$(CONFIG_EVENT_TRACER) += trace_events_filter.o
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libftrace-y := ftrace.o
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