Hello all, This series is meant to address two issues with the latency tracing.
The first three patches provide a method to trace latencies that always occurs very close to each other and to differentiate between them, in spite of the fact that the latency tracers always work in overwrite mode. [PATCH 1/4] This implement fs notification for preempt/irqsoff. It makes it possible for userspace to detect when a new latency has been detected. [PATCH 2/4] This extends the preemptirq_delay_test module so that it can be used to generate a burst of closely occurring latencies. [PATCH 3/4] This adds a user space program to the tools directory that utilizes the fs notification feature and a randomized algorithm to print out any of the latencies in a burst with approximately equal probability. The last patch is not directly connected but doesn't apply cleanly on its own: [PATCH 4/4] This adds the option CONFIG_TRACE_CONSOLE_LATENCY to decide whether we want to trace prints to the console or not. best regards, Viktor Rosendahl Viktor Rosendahl (4): ftrace: Implement fs notification for preempt/irqsoff tracers preemptirq_delay_test: Add the burst feature and a sysfs trigger Add the latency-collector to tools ftrace: Add an option for tracing console latencies include/linux/irqflags.h | 13 + kernel/printk/printk.c | 5 +- kernel/trace/Kconfig | 21 + kernel/trace/preemptirq_delay_test.c | 139 ++- kernel/trace/trace.c | 31 +- kernel/trace/trace.h | 5 + kernel/trace/trace_irqsoff.c | 35 + tools/Makefile | 14 +- tools/trace/Makefile | 20 + tools/trace/latency-collector.c | 1190 ++++++++++++++++++++++++++ 10 files changed, 1444 insertions(+), 29 deletions(-) create mode 100644 tools/trace/Makefile create mode 100644 tools/trace/latency-collector.c -- 2.17.1