diff options
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 37 |
1 files changed, 27 insertions, 10 deletions
diff --git a/init/Kconfig b/init/Kconfig index cfdf5c32280..706728be312 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -920,26 +920,31 @@ config HAVE_PERF_EVENTS help See tools/perf/design.txt for details. -menu "Performance Counters" +menu "Kernel Performance Events And Counters" config PERF_EVENTS - bool "Kernel Performance Counters" - default y if PROFILING + bool "Kernel performance events and counters" + default y if (PROFILING || PERF_COUNTERS) depends on HAVE_PERF_EVENTS select ANON_INODES help - Enable kernel support for performance counter hardware. + Enable kernel support for various performance events provided + by software and hardware. - Performance counters are special hardware registers available - on most modern CPUs. These registers count the number of certain + Software events are supported either build-in or via the + use of generic tracepoints. + + Most modern CPUs support performance events via performance + counter registers. These registers count the number of certain types of hw events: such as instructions executed, cachemisses suffered, or branches mis-predicted - without slowing down the kernel or applications. These registers can also trigger interrupts when a threshold number of events have passed - and can thus be used to profile the code that runs on that CPU. - The Linux Performance Counter subsystem provides an abstraction of - these hardware capabilities, available via a system call. It + The Linux Performance Event subsystem provides an abstraction of + these software and hardware cevent apabilities, available via a + system call and used by the "perf" utility in tools/perf/. It provides per task and per CPU counters, and it provides event capabilities on top of those. @@ -950,14 +955,26 @@ config EVENT_PROFILE depends on PERF_EVENTS && EVENT_TRACING default y help - Allow the use of tracepoints as software performance counters. + Allow the use of tracepoints as software performance events. - When this is enabled, you can create perf counters based on + When this is enabled, you can create perf events based on tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID found in debugfs://tracing/events/*/*/id. (The -e/--events option to the perf tool can parse and interpret symbolic tracepoints, in the subsystem:tracepoint_name format.) +config PERF_COUNTERS + bool "Kernel performance counters (old config option)" + depends on HAVE_PERF_EVENTS + help + This config has been obsoleted by the PERF_EVENTS + config option - please see that one for details. + + It has no effect on the kernel whether you enable + it or not, it is a compatibility placeholder. + + Say N if unsure. + endmenu config VM_EVENT_COUNTERS |