| libtracecmd(3) |
| ============= |
| |
| NAME |
| ---- |
| tracecmd_read_cpu_first, tracecmd_read_data, tracecmd_read_at, |
| tracecmd_free_record, tracecmd_get_tep - Read recorded events from a trace file. |
| |
| SYNOPSIS |
| -------- |
| [verse] |
| -- |
| *#include <trace-cmd.h>* |
| |
| struct tep_record pass:[*]*tracecmd_read_cpu_first*(struct tracecmd_input pass:[*]_handle_, int _cpu_); |
| struct tep_record pass:[*]*tracecmd_read_data*(struct tracecmd_input pass:[*]_handle_, int _cpu_); |
| struct tep_record pass:[*]*tracecmd_read_at*(struct tracecmd_input pass:[*]_handle_, unsigned long long _offset_, int pass:[*]_cpu_); |
| void *tracecmd_free_record*(struct tep_record pass:[*]_record_); |
| struct tep_handle pass:[*]*tracecmd_get_tep*(struct tracecmd_input pass:[*]_handle_); |
| -- |
| |
| DESCRIPTION |
| ----------- |
| This set of APIs can be used to read tracing data from a trace file opened |
| with _tracecmd_open()(3)_, _tracecmd_open_fd()(3)_ or _tracecmd_open_head()(3)_. |
| |
| The _tracecmd_read_cpu_first()_ function reads the first trace record |
| for a given _cpu_ from a trace file associated with _handle_. The returned |
| record must be freed with _tracecmd_free_record()_. |
| |
| The _tracecmd_read_data()_ function reads the next trace record for |
| a given _cpu_ from a trace file associated with _handle_ and increments |
| the read location pointer, so that the next call to _tracecmd_read_data()_ |
| will not read the same record again. The returned record must be freed |
| with _tracecmd_free_record()_. |
| |
| The _tracecmd_read_at()_ function reads a trace record from a specific |
| _offset_ within the file associated with _handle_. The CPU on which the |
| recorded event occurred is stored in the _cpu_. The function does not |
| change the current read location pointer. The returned record must be |
| freed with _tracecmd_free_record()_. |
| |
| The _tracecmd_free_record()_ function frees a _record_ returned by any |
| of the _tracecmd_read__ APIs. |
| |
| The _tracecmd_get_tep()_ function returns a tep context for a given |
| _handle_. |
| |
| RETURN VALUE |
| ------------ |
| The _tracecmd_read_cpu_first()_, _tracecmd_read_data()_ and |
| _tracecmd_read_at()_ functions return a pointer to struct tep_record or |
| NULL in case of an error.The returned record must be freed with |
| _tracecmd_free_record()_. |
| |
| The _tracecmd_get_tep()_ function returns a pointer to tep context or |
| NULL if there is no tep context for the given _handle_. The returned |
| tep pointer must *not* be freed. |
| |
| EXAMPLE |
| ------- |
| [source,c] |
| -- |
| #include <trace-cmd.h> |
| ... |
| struct tracecmd_input *handle = tracecmd_open("trace.dat"); |
| if (!handle) { |
| /* Failed to open trace.dat file */ |
| } |
| ... |
| unsigned long long offset = 0; |
| struct tep_record *rec; |
| int cpu = 0; |
| rec = tracecmd_read_cpu_first(handle, cpu); |
| while (rec) { |
| ... |
| if ( /* some interesting record noticed */) { |
| /* store the offset of the interesting record */ |
| offset = rec->offset; |
| } |
| ... |
| tracecmd_free_record(rec); |
| rec = tracecmd_read_data(handle, cpu); |
| } |
| ... |
| if (offset) { |
| rec = tracecmd_read_at(handle, offset, &cpu); |
| if (rec) { |
| /* Got record at offset on cpu */ |
| ... |
| tracecmd_free_record(rec); |
| } |
| } |
| |
| ... |
| tracecmd_close(hadle); |
| |
| -- |
| FILES |
| ----- |
| [verse] |
| -- |
| *trace-cmd.h* |
| Header file to include in order to have access to the library APIs. |
| *-ltracecmd* |
| Linker switch to add when building a program that uses the library. |
| -- |
| |
| SEE ALSO |
| -------- |
| _libtracefs(3)_, |
| _libtraceevent(3)_, |
| _trace-cmd(1)_ |
| _trace-cmd.dat(5)_ |
| |
| AUTHOR |
| ------ |
| [verse] |
| -- |
| *Steven Rostedt* <[email protected]> |
| *Tzvetomir Stoyanov* <[email protected]> |
| -- |
| REPORTING BUGS |
| -------------- |
| Report bugs to <[email protected]> |
| |
| LICENSE |
| ------- |
| libtracecmd is Free Software licensed under the GNU LGPL 2.1 |
| |
| RESOURCES |
| --------- |
| https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git/ |
| |
| COPYING |
| ------- |
| Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under |
| the terms of the GNU Public License (GPL). |
