From: "Steven Rostedt (Red Hat)" The snapshot utility is extremely useful, and does not add any more overhead in memory when another latency tracer is enabled. They use the snapshot underneath. There's no reason to hide the snapshot file when a latency tracer has been enabled in the kernel. If any of the latency tracers (irq, preempt or wakeup) is enabled then also select the snapshot facility. Note, snapshot can be enabled without the latency tracers enabled. Signed-off-by: Steven Rostedt --- kernel/trace/Kconfig | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index b516a8e..590a27f 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -191,6 +191,7 @@ config IRQSOFF_TRACER select GENERIC_TRACER select TRACER_MAX_TRACE select RING_BUFFER_ALLOW_SWAP + select TRACER_SNAPSHOT help This option measures the time spent in irqs-off critical sections, with microsecond accuracy. @@ -213,6 +214,7 @@ config PREEMPT_TRACER select GENERIC_TRACER select TRACER_MAX_TRACE select RING_BUFFER_ALLOW_SWAP + select TRACER_SNAPSHOT help This option measures the time spent in preemption-off critical sections, with microsecond accuracy. @@ -232,6 +234,7 @@ config SCHED_TRACER select GENERIC_TRACER select CONTEXT_SWITCH_TRACER select TRACER_MAX_TRACE + select TRACER_SNAPSHOT help This tracer tracks the latency of the highest priority task to be scheduled in, starting from the point it has woken up. -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/