kernel/linux.git/Documentation/trace/histogram.rst, branch v5.19

tracing/histogram: Update division by 0 documentation

2021-11-02T00:46:29+00:00

If the divisor is a constant and zero, the undeifned case can be detected and an error returned instead of -1. Link: https://lkml.kernel.org/r/20211029183339.3216491-3-kaleshsingh@google.com Cc: Jonathan Corbet Cc: Ingo Molnar Cc: Shuah Khan Cc: Tom Zanussi Signed-off-by: Kalesh Singh Signed-off-by: Steven Rostedt (VMware)

tracing/histogram: Fix documentation inline emphasis warning

2021-10-29T01:21:45+00:00

This fixes the warning: Documentation/trace/histogram.rst:1766: WARNING: Inline emphasis start-string without end-string The issue was caused by an unescaped '*' character. Link: https://lore.kernel.org/all/20211028170548.2597449-1-kaleshsingh@google.com/T/#m77da47432f5cc6521d4294ffdb9621949cc35d04 Link: https://lkml.kernel.org/r/20211028170548.2597449-1-kaleshsingh@google.com Fixes: 2d2f6d4b8ce7 ("tracing/histogram: Document expression arithmetic and constants") Reported-by: Stephen Rothwell Signed-off-by: Kalesh Singh Signed-off-by: Steven Rostedt (VMware)

tracing/histogram: Document expression arithmetic and constants

2021-10-27T00:27:20+00:00

Histogram expressions now support division, and multiplication in addition to the already supported subtraction and addition operators. Numeric constants can also be used in a hist trigger expressions or assigned to a variable and used by refernce in an expression. Link: https://lkml.kernel.org/r/20211025200852.3002369-9-kaleshsingh@google.com Signed-off-by: Kalesh Singh Reviewed-by: Namhyung Kim Signed-off-by: Steven Rostedt (VMware)

tracing/doc: Fix table format in histogram code

2021-08-24T13:48:34+00:00

The addition of the buckets conversion for the histogram code, updated the documentation table of available conversions, but did not update the format to accommodate the extra size needed to cover the description. Link: https://lkml.kernel.org/r/20210823100007.71ce2ba9@oasis.local.home Reported-by: Stephen Rothwell Tested-by: Stephen Rothwell Signed-off-by: Steven Rostedt (VMware)

tracing/histogram: Update the documentation for the buckets modifier

2021-08-16T15:37:20+00:00

Update both the tracefs README file as well as the histogram.rst to include an explanation of what the buckets modifier is and how to use it. Include an example with the wakeup_latency example for both log2 and the buckets modifiers as there was no existing log2 example. Link: https://lkml.kernel.org/r/20210707213922.167218794@goodmis.org Acked-by: Namhyung Kim Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

tracing/histogram: Rename "cpu" to "common_cpu"

2021-07-23T12:44:47+00:00

Currently the histogram logic allows the user to write "cpu" in as an event field, and it will record the CPU that the event happened on. The problem with this is that there's a lot of events that have "cpu" as a real field, and using "cpu" as the CPU it ran on, makes it impossible to run histograms on the "cpu" field of events. For example, if I want to have a histogram on the count of the workqueue_queue_work event on its cpu field, running: ># echo 'hist:keys=cpu' > events/workqueue/workqueue_queue_work/trigger Gives a misleading and wrong result. Change the command to "common_cpu" as no event should have "common_*" fields as that's a reserved name for fields used by all events. And this makes sense here as common_cpu would be a field used by all events. Now we can even do: ># echo 'hist:keys=common_cpu,cpu if cpu < 100' > events/workqueue/workqueue_queue_work/trigger ># cat events/workqueue/workqueue_queue_work/hist # event histogram # # trigger info: hist:keys=common_cpu,cpu:vals=hitcount:sort=hitcount:size=2048 if cpu < 100 [active] # { common_cpu: 0, cpu: 2 } hitcount: 1 { common_cpu: 0, cpu: 4 } hitcount: 1 { common_cpu: 7, cpu: 7 } hitcount: 1 { common_cpu: 0, cpu: 7 } hitcount: 1 { common_cpu: 0, cpu: 1 } hitcount: 1 { common_cpu: 0, cpu: 6 } hitcount: 2 { common_cpu: 0, cpu: 5 } hitcount: 2 { common_cpu: 1, cpu: 1 } hitcount: 4 { common_cpu: 6, cpu: 6 } hitcount: 4 { common_cpu: 5, cpu: 5 } hitcount: 14 { common_cpu: 4, cpu: 4 } hitcount: 26 { common_cpu: 0, cpu: 0 } hitcount: 39 { common_cpu: 2, cpu: 2 } hitcount: 184 Now for backward compatibility, I added a trick. If "cpu" is used, and the field is not found, it will fall back to "common_cpu" and work as it did before. This way, it will still work for old programs that use "cpu" to get the actual CPU, but if the event has a "cpu" as a field, it will get that event's "cpu" field, which is probably what it wants anyway. I updated the tracefs/README to include documentation about both the common_timestamp and the common_cpu. This way, if that text is present in the README, then an application can know that common_cpu is supported over just plain "cpu". Link: https://lkml.kernel.org/r/20210721110053.26b4f641@oasis.local.home Cc: Namhyung Kim Cc: Ingo Molnar Cc: Andrew Morton Cc: stable@vger.kernel.org Fixes: 8b7622bf94a44 ("tracing: Add cpu field for hist triggers") Reviewed-by: Tom Zanussi Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware)

Merge tag 'trace-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2020-10-15T22:51:28+00:00

Pull tracing updates from Steven Rostedt: "Updates for tracing and bootconfig: - Add support for "bool" type in synthetic events - Add per instance tracing for bootconfig - Support perf-style return probe ("SYMBOL%return") in kprobes and uprobes - Allow for kprobes to be enabled earlier in boot up - Added tracepoint helper function to allow testing if tracepoints are enabled in headers - Synthetic events can now have dynamic strings (variable length) - Various fixes and cleanups" * tag 'trace-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (58 commits) tracing: support "bool" type in synthetic trace events selftests/ftrace: Add test case for synthetic event syntax errors tracing: Handle synthetic event array field type checking correctly selftests/ftrace: Change synthetic event name for inter-event-combined test tracing: Add synthetic event error logging tracing: Check that the synthetic event and field names are legal tracing: Move is_good_name() from trace_probe.h to trace.h tracing: Don't show dynamic string internals in synthetic event description tracing: Fix some typos in comments tracing/boot: Add ftrace.instance.*.alloc_snapshot option tracing: Fix race in trace_open and buffer resize call tracing: Check return value of __create_val_fields() before using its result tracing: Fix synthetic print fmt check for use of __get_str() tracing: Remove a pointless assignment ftrace: ftrace_global_list is renamed to ftrace_ops_list ftrace: Format variable declarations of ftrace_allocate_records ftrace: Simplify the calculation of page number for ftrace_page->records ftrace: Simplify the dyn_ftrace->flags macro ftrace: Simplify the hash calculation ftrace: Use fls() to get the bits for dup_hash() ...

tracing: Add support for dynamic strings to synthetic events

2020-10-05T23:32:18+00:00

Currently, sythetic events only support static string fields such as: # echo 'test_latency u64 lat; char somename[32]' > /sys/kernel/debug/tracing/synthetic_events Which is fine, but wastes a lot of space in the event. It also prevents the most commonly-defined strings in the existing trace events e.g. those defined using __string(), from being passed to synthetic events via the trace() action. With this change, synthetic events with dynamic fields can be defined: # echo 'test_latency u64 lat; char somename[]' > /sys/kernel/debug/tracing/synthetic_events And the trace() action can be used to generate events using either dynamic or static strings: # echo 'hist:keys=name:lat=common_timestamp.usecs-$ts0:onmatch(sys.event).test_latency($lat,name)' > /sys/kernel/debug/tracing/events The synthetic event dynamic strings are implemented in the same way as the existing __data_loc strings and appear as such in the format file. [ : added __set_synth_event_print_fmt() changes: I added the following to make it work with trace-cmd. Dynamic strings must have __get_str() for events in the print_fmt otherwise it can't be parsed correctly. ] Link: https://lore.kernel.org/r/cover.1601588066.git.zanussi@kernel.org Link: https://lkml.kernel.org/r/3ed35b6d0e390f5b94cb4a9ba1cc18f5982ab277.1601848695.git.zanussi@kernel.org Tested-by: Axel Rasmussen Signed-off-by: Tom Zanussi Signed-off-by: Steven Rostedt (VMware)

tracing: switch to kernel_clone()

2020-08-20T11:12:59+00:00

The old _do_fork() helper is removed in favor of the new kernel_clone() helper. The latter adheres to naming conventions for kernel internal syscall helpers. Signed-off-by: Christian Brauner Cc: Mauro Carvalho Chehab Cc: Alexandre Chartre Cc: Jonathan Corbet Cc: Thomas Gleixner Cc: Masami Hiramatsu Cc: Shuah Khan Cc: Ingo Molnar Cc: Steven Rostedt Cc: Xiao Yang Cc: Tom Zanussi Cc: linux-doc@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Link: https://lore.kernel.org/r/20200819104655.436656-11-christian.brauner@ubuntu.com

docs: tracing: Fix typos in histogram.rst

2019-05-29T21:49:01+00:00

This patch fixes some spelling typos in histogram.rst Signed-off-by: Masanari Iida Acked-by: Steven Rostedt (VMware) Signed-off-by: Jonathan Corbet