From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx> Add man pages for: traceeval_delta_init() traceeval_delta_init_size() traceeval_delta_release() traceeval_delta_start() traceeval_delta_start_size() traceeval_delta_stop() traceeval_delta_stop_size() traceeval_delta_continue() traceeval_delta_continue_size() Link: https://lore.kernel.org/linux-trace-devel/20231006185405.1379249-2-rostedt@xxxxxxxxxxx Cc: Ross Zwisler <zwisler@xxxxxxxxxx> Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> --- Documentation/libtraceeval-delta-init.txt | 346 ++++++++++++++++++++++ Documentation/libtraceeval.txt | 29 ++ check-manpages.sh | 2 +- 3 files changed, 376 insertions(+), 1 deletion(-) create mode 100644 Documentation/libtraceeval-delta-init.txt diff --git a/Documentation/libtraceeval-delta-init.txt b/Documentation/libtraceeval-delta-init.txt new file mode 100644 index 000000000000..9d37035dcd60 --- /dev/null +++ b/Documentation/libtraceeval-delta-init.txt @@ -0,0 +1,346 @@ +libtraceeval(3) +=============== + +NAME +---- +traceeval_delta_init, traceeval_delta_init_size, traceeval_delta_release, +traceeval_delta_start, traceeval_delta_start_size, traceeval_delta_stop, +traceeval_delta_stop_size, traceeval_delta_continue, traceeval_delta_continue_size +- Create and start/stop a traceeval_delta instance + +SYNOPSIS +-------- +[verse] +-- +*#include <traceeval.h>* + +struct traceeval_delta pass:[*]*traceeval_delta_init*(struct traceeval_type pass:[*]_keys_, + struct traceeval_type pass:[*]_vals_); +struct traceeval_delta pass:[*]*traceeval_delta_init_size*(struct traceeval_type pass:[*]_keys_, + struct traceeval_type pass:[*]_vals_, + size_t _nr_keys_, size_t _nr_vals_); +void *traceeval_delta_release*(struct traceeval_delta pass:[*]tdelta); + +int *traceeval_delta_start*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, + unsigned long long _timestamp_); +int *traceeval_delta_start_size*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]keys, size_t _nr_keys_, + unsigned long long _timestamp_); + +int *traceeval_delta_stop*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, + unsigned long long _timestamp_); +int *traceeval_delta_stop_size*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, size_t _nr_keys_, + unsigned long long _timestamp_); + +int *traceeval_delta_continue*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, + unsigned long long _timestamp_); +int *traceeval_delta_continue_size*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]keys, size_t _nr_keys_, + unsigned long long _timestamp_); +-- + +DESCRIPTION +----------- +The traceeval handles mapping keys and values for various events. One common use case +is to attach two traceevals together via the same keys, and to have one of the values +be a timestamp. The first event would record the current timestamp and the second +event would query the traceeval that is used by the first event using the current +keys to retrieve the timestamp of the event that matches the second event. This +timestamp would be used to calculate the delta between the current timestamp, and that +would be saved in another traceeval to record the deltas. This delta value would be +tagged as a TRACEEVAL_FL_STAT to keep track of the maximum and mimimum deltas along +with the timestamp of where those occurred. + +Since the above is very common, the traceeval_delta is used to facilitate this approach. +Instead of having two traceevals to handle this situation, a single traceeval_delta +can be used. + +The *traceeval_delta_init()* takes the _keys_ and _vals_ just like *traceeval_init*(3) +does. The difference is that this function will add two additional values to hold +a timestamp and the delta. The _keys_ must be something that can match the two events +that are to be timed. The _vals_ is optional and can accept NULL. If _vals_ is used +it can be returned by *traceeval_delta_query*(3) and from *traceeval_iterator_query*(3). + +The _keys_ and _vals_ passed to *traceeval_delta_init()* must be a static array. If +dynamically sized arrays are to be required, then *traceeval_delta_init_size()* can be +used and the caller can pass in _nr_keys_ to denote how many _keys_ are being passed in +as well as _nr_vals_ to denote how many _vals_ are passed in (0 for NULL). + +The *traceeval_delta_release()* frees all the resources of a traceeval_delta created +by *traceeval_delta_init()* or *traceeval_delta_init_size()*. + +The traceeval_delta is for timing between two events, and only the _keys_ and _timestamp_ need +to be used to do so. When the starting event is found, a call to *traceeval_delta_start()* +is done passing in the _keys_ that differentiate the event and will map to the stopping event, +and the _timestamp_ to start the timings. This will be saved in the _tdelta_ that was created +by one of the *traceeval_delta_init()* functions. + +When an ending event is found and a delta is to be recorded from the starting event, +*traceeval_delta_stop()* is used. Passing the _keys_ that match the starting event +and a _timestamp_ to calculate the delta, where this timestamp will subtract +the timestamp passed to *traceeval_delta_start()* or *traceeval_delta_continue()* +to create the delta between the two and save that in the given _tdelta_. + +There's some cases where there may be more than one starting event, and the first +starting event is to be required for starting the timings and any new starting event +that happens before an ending event occurs should be ignored. In this case, +*traceeval_delta_continue()* is used. It acts the same as *traceeval_delta_start()* +except that if the matching _keys_ have not encountered a *traceeval_delta_stop()* +since a previous *traceeval_delta_start()* or *traceeval_delta_continue()* then +the _tdelta_ will not be updated. + +To describe one use case for this, if the runtime of a CPU is being recorded, +and anytime a task is scheduled on the CPU, it is considered a starting event, +but the delta should be only used when the CPU switches from idle to running a task, +*traceeval_delta_continue()* can be used whenever a task is scheduled on the CPU +and *traceeval_delta_stop()* can be used when the CPU goes idle. Only the first +occurrence of a task scheduling on the CPU will start the timing. If a task +is scheduled on the CPU when another task was already running, no update should +be made. If *traceeval_delta_start()* is used, the timestamp of the start event +will be that of the time the new task came onto the CPU preempting the previous +task and that would only show the runtime of the last task and not how long the +CPU itself was running tasks. + +The *traceeval_delta_continue()* _keys_ must be a static array, if a dynamic array +is required then *traceveal_delta_continue_size()* is to be used to specify the +size of _keys_ with _nr_keys_. + +RETURN VALUE +------------ +The *traceeval_delta_init()* and *traceeval_delta_init_size()* both return a descriptor +to the traceeval_delta or NULL on error. + +The *traceeval_delta_start()*, *traceeval_delta_start_size()*, *traceeval_delta_stop()*, +*traceeval_delta_stop_size()*, traceeval_delta_continue()* and *traceeval_delta_continue_size()* +all return 0 on success and -1 on error. + +EXAMPLE +------- +[source,c] +-- +#include <trace-cmd.h> +#include <traceeval.h> + +static struct traceeval_type task_types[] = { + { + .name = "COMM", + .type = TRACEEVAL_TYPE_STRING, + }, + { + .name = "PID", + .type = TRACEEVAL_TYPE_NUMBER, + } +}; + +static struct traceeval_type cpu_types[] = { + { + .name = "CPU", + .type = TRACEEVAL_TYPE_NUMBER, + } +}; + +struct data { + struct traceeval_delta *tdelta_tasks; + struct traceeval_delta *tdelta_cpus; +}; + +static struct tep_format_field *get_field(struct tep_event *event, const char *name) +{ + static struct tep_format_field *field; + + field = tep_find_field(event, name); + if (!field) { + fprintf(stderr, "Could not find field %s for %s", name, event->name); + exit(-1); + } + + return field; +} + +static int switch_func(struct tracecmd_input *handle, struct tep_event *event, + struct tep_record *record, int cpu, void *d) +{ + static struct tep_format_field *prev_comm; + static struct tep_format_field *prev_pid; + static struct tep_format_field *next_comm; + static struct tep_format_field *next_pid; + struct traceeval_data task_keys[2]; + struct traceeval_data cpu_keys[1]; + struct data *data = d; + unsigned long long val; + const char *comm; + + if (!next_comm) { + prev_comm = get_field(event, "prev_comm"); + prev_pid = get_field(event, "prev_pid"); + + next_comm = get_field(event, "next_comm"); + next_pid = get_field(event, "next_pid"); + } + + comm = record->data + prev_comm->offset; + tep_read_number_field(prev_pid, record->data, &val); + + TRACEEVAL_SET_CSTRING(task_keys[0], comm); + TRACEEVAL_SET_NUMBER(task_keys[1], val); + + if (val) + traceeval_delta_stop(data->tdelta_tasks, task_keys, record->ts); + + comm = record->data + next_comm->offset; + tep_read_number_field(next_pid, record->data, &val); + + TRACEEVAL_SET_CSTRING(task_keys[0], comm); + TRACEEVAL_SET_NUMBER(task_keys[1], val); + + TRACEEVAL_SET_NUMBER(cpu_keys[0], record->cpu); + + if (val) { + if (traceeval_delta_start(data->tdelta_tasks, task_keys, record->ts) < 0) + printf("FAILED\n"); + traceeval_delta_continue(data->tdelta_cpus, cpu_keys, record->ts); + } else { + traceeval_delta_stop(data->tdelta_cpus, cpu_keys, record->ts); + } + + return 0; +} + +static void print_microseconds(int idx, unsigned long long nsecs) +{ + unsigned long long usecs; + + usecs = nsecs / 1000; + if (!nsecs || usecs) + printf("%*lld", idx, usecs); + else + printf("%*d.%03lld", idx, 0, nsecs); +} + +static void print_stat(struct traceeval_stat *stat) +{ + unsigned long long total; + unsigned long long cnt; + unsigned long long ts; + + printf("\tmax: "); + print_microseconds(12, traceeval_stat_max_timestamp(stat, &ts)); + printf(" timestamp: "); + print_microseconds(10, ts); + printf("\n\tmin: "); + print_microseconds(12, traceeval_stat_min_timestamp(stat, &ts)); + printf(" timestamp: "); + print_microseconds(10, ts); + printf("\n\ttotal: "); + total = traceeval_stat_total(stat); + print_microseconds(10, total); + cnt = traceeval_stat_count(stat); + printf("\n\tcount: %*lld\n", 10, cnt); + printf("\taverage:"); + print_microseconds(9, cnt ? total / cnt : 0); + printf("\n"); +} + +static void display_cpus(struct traceeval_delta *tdelta) +{ + struct traceeval *teval = traceeval_delta_teval_get(tdelta); + struct traceeval_iterator *iter = traceeval_iterator_get(teval); + const struct traceeval_data *keys; + + printf("\n"); + + traceeval_iterator_sort(iter, cpu_types[0].name, 0, true); + + while (traceeval_iterator_next(iter, &keys) > 0) { + struct traceeval_stat *stat; + + stat = traceeval_iterator_delta_stat(iter); + + printf("CPU [%zd]:\n", keys[0].number); + print_stat(stat); + } + traceeval_delta_teval_put(teval); +} + +static void display_tasks(struct traceeval_delta *tdelta) +{ + struct traceeval *teval = traceeval_delta_teval_get(tdelta); + struct traceeval_iterator *iter = traceeval_iterator_get(teval); + const struct traceeval_data *keys; + + printf("\n"); + + traceeval_iterator_sort(iter, task_types[0].name, 0, true); + traceeval_iterator_sort(iter, task_types[1].name, 1, true); + + while (traceeval_iterator_next(iter, &keys) > 0) { + struct traceeval_stat *stat; + + stat = traceeval_iterator_delta_stat(iter); + + printf("Task %s [%zd]:\n", keys[0].cstring, keys[1].number); + print_stat(stat); + } + traceeval_delta_teval_put(teval); +}; + +int main (int argc, char **argv) +{ + struct tracecmd_input *handle; + struct data data; + + if (argc < 2) { + printf("Need to pass trace.dat file to this\n"); + exit(-1); + } + + handle = tracecmd_open(argv[1], TRACECMD_FL_LOAD_NO_PLUGINS); + + data.tdelta_tasks = traceeval_delta_init(task_types, NULL); + data.tdelta_cpus = traceeval_delta_init(cpu_types, NULL); + + tracecmd_follow_event(handle, "sched", "sched_switch", switch_func, &data); + tracecmd_iterate_events(handle, NULL, 0, NULL, NULL); + + display_cpus(data.tdelta_cpus); + display_tasks(data.tdelta_tasks); + + traceeval_delta_release(data.tdelta_cpus); + traceeval_delta_release(data.tdelta_tasks); + + return 0; +} +-- + +FILES +----- +[verse] +-- +*traceval.h* + Header file to include in order to have access to the library APIs. +*-ltraceeval* + Linker switch to add when building a program that uses the library. +-- + +SEE ALSO +-------- +*libtraceeval*(3) + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* <rostedt@xxxxxxxxxxx>, author of *libtraceeval*. +-- +REPORTING BUGS +-------------- +Report bugs to <linux-trace-devel@xxxxxxxxxxxxxxx> + +LICENSE +------- +libtraceeval is licensed under MIT. + diff --git a/Documentation/libtraceeval.txt b/Documentation/libtraceeval.txt index 173b1ddb3df8..4d23ba0c5928 100644 --- a/Documentation/libtraceeval.txt +++ b/Documentation/libtraceeval.txt @@ -74,6 +74,35 @@ Functions to manage statistics of values of a traceeval: unsigned long long *traceeval_stat_min_timestamp*(struct traceeval_stat pass:[*]_stat_, unsigned long long pass:[*]ts); unsigned long long *traceeval_stat_total*(struct traceeval_stat pass:[*]_stat_); unsigned long long *traceeval_stat_count*(struct traceeval_stat pass:[*]_stat_); + +Handling delta times between events: + struct traceeval_delta pass:[*]*traceeval_delta_init*(struct traceeval_type pass:[*]_keys_, + struct traceeval_type pass:[*]_vals_); + struct traceeval_delta pass:[*]*traceeval_delta_init_size*(struct traceeval_type pass:[*]_keys_, + struct traceeval_type pass:[*]_vals_, + size_t _nr_keys_, size_t _nr_vals_); + void *traceeval_delta_release*(struct traceeval_delta pass:[*]tdelta); + + int *traceeval_delta_start*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, + unsigned long long _timestamp_); + int *traceeval_delta_start_size*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]keys, size_t _nr_keys_, + unsigned long long _timestamp_); + + int *traceeval_delta_stop*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, + unsigned long long _timestamp_); + int *traceeval_delta_stop_size*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, size_t _nr_keys_, + unsigned long long _timestamp_); + + int *traceeval_delta_continue*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]_keys_, + unsigned long long _timestamp_); + int *traceeval_delta_continue_size*(struct traceeval_delta pass:[*]_tdelta_, + const struct traceeval_data pass:[*]keys, size_t _nr_keys_, + unsigned long long _timestamp_); -- DESCRIPTION diff --git a/check-manpages.sh b/check-manpages.sh index 07acc12ecbc4..b62406cce242 100755 --- a/check-manpages.sh +++ b/check-manpages.sh @@ -45,7 +45,7 @@ for man in ${MAIN}-*.txt; do done # traceeval_init_data_size is not deprecated, but users shouldn't be using it directly. -DEPRECATED="*traceeval_init_data_size*" +DEPRECATED="*traceeval_init_data_size* *traceeval_delta_init_data_size*" last="" sed -ne 's/^[a-z].*[ \*]\([a-z_][a-z_]*\)(.*/\1/p' -e 's/^\([a-z_][a-z_]*\)(.*/\1/p' ../include/traceeval.h | while read f; do -- 2.40.1
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