From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- tools/perf/Documentation/perf-timechart.txt | 134 ++++++++++++++++++++++++++++ 1 file changed, 134 insertions(+) create mode 100644 tools/perf/Documentation/perf-timechart.txt (limited to 'tools/perf/Documentation/perf-timechart.txt') diff --git a/tools/perf/Documentation/perf-timechart.txt b/tools/perf/Documentation/perf-timechart.txt new file mode 100644 index 000000000..bacc5df3c --- /dev/null +++ b/tools/perf/Documentation/perf-timechart.txt @@ -0,0 +1,134 @@ +perf-timechart(1) +================= + +NAME +---- +perf-timechart - Tool to visualize total system behavior during a workload + +SYNOPSIS +-------- +[verse] +'perf timechart' [] {record} [] + +DESCRIPTION +----------- +There are two variants of perf timechart: + + 'perf timechart record ' to record the system level events + of an arbitrary workload. By default timechart records only scheduler + and CPU events (task switches, running times, CPU power states, etc), + but it's possible to record IO (disk, network) activity using -I argument. + + 'perf timechart' to turn a trace into a Scalable Vector Graphics file, + that can be viewed with popular SVG viewers such as 'Inkscape'. Depending + on the events in the perf.data file, timechart will contain scheduler/cpu + events or IO events. + + In IO mode, every bar has two charts: upper and lower. + Upper bar shows incoming events (disk reads, ingress network packets). + Lower bar shows outgoing events (disk writes, egress network packets). + There are also poll bars which show how much time application spent + in poll/epoll/select syscalls. + +TIMECHART OPTIONS +----------------- +-o:: +--output=:: + Select the output file (default: output.svg) +-i:: +--input=:: + Select the input file (default: perf.data unless stdin is a fifo) +-w:: +--width=:: + Select the width of the SVG file (default: 1000) +-P:: +--power-only:: + Only output the CPU power section of the diagram +-T:: +--tasks-only:: + Don't output processor state transitions +-p:: +--process:: + Select the processes to display, by name or PID +-f:: +--force:: + Don't complain, do it. +--symfs=:: + Look for files with symbols relative to this directory. The optional + layout can be 'hierarchy' (default, matches full path) or 'flat' + (only matches base name). This is useful when debug files are stored + in a flat directory structure. +-n:: +--proc-num:: + Print task info for at least given number of tasks. +-t:: +--topology:: + Sort CPUs according to topology. +--highlight=:: + Highlight tasks (using different color) that run more than given + duration or tasks with given name. If number is given it's interpreted + as number of nanoseconds. If non-numeric string is given it's + interpreted as task name. +--io-skip-eagain:: + Don't draw EAGAIN IO events. +--io-min-time=:: + Draw small events as if they lasted min-time. Useful when you need + to see very small and fast IO. It's possible to specify ms or us + suffix to specify time in milliseconds or microseconds. + Default value is 1ms. +--io-merge-dist=:: + Merge events that are merge-dist nanoseconds apart. + Reduces number of figures on the SVG and makes it more render-friendly. + It's possible to specify ms or us suffix to specify time in + milliseconds or microseconds. + Default value is 1us. + +RECORD OPTIONS +-------------- +-P:: +--power-only:: + Record only power-related events +-T:: +--tasks-only:: + Record only tasks-related events +-I:: +--io-only:: + Record only io-related events +-g:: +--callchain:: + Do call-graph (stack chain/backtrace) recording +-o:: +--output=:: + Select the output file (default: perf.data) + +EXAMPLES +-------- + +$ perf timechart record git pull + + [ perf record: Woken up 13 times to write data ] + [ perf record: Captured and wrote 4.253 MB perf.data (~185801 samples) ] + +$ perf timechart + + Written 10.2 seconds of trace to output.svg. + +Record system-wide timechart: + + $ perf timechart record + + then generate timechart and highlight 'gcc' tasks: + + $ perf timechart --highlight gcc + +Record system-wide IO events: + + $ perf timechart record -I + + then generate timechart: + + $ perf timechart + +SEE ALSO +-------- +linkperf:perf-record[1] -- cgit v1.3.1