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authorIngo Molnar <mingo@kernel.org>2019-05-18 10:24:43 +0200
committerIngo Molnar <mingo@kernel.org>2019-05-18 10:24:43 +0200
commit62e1c09418fc16d27720b128275cac61367e2c1b (patch)
tree4759aa6662b1398e2b93696ace58f6f309722b06 /tools/lib/traceevent/Documentation/libtraceevent-reg_event_handler.txt
parent01be377c62210a8d8fef35be906f9349591bb7cd (diff)
parent4fc4d8dfa056dfd48afe73b9ea3b7570ceb80b9c (diff)
Merge tag 'perf-core-for-mingo-5.2-20190517' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core
Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo: perf.data: Alexey Budankov: - Streaming compression of perf ring buffer into PERF_RECORD_COMPRESSED user space records, resulting in ~3-5x perf.data file size reduction on variety of tested workloads what saves storage space on larger server systems where perf.data size can easily reach several tens or even hundreds of GiBs, especially when profiling with DWARF-based stacks and tracing of context switches. perf record: Arnaldo Carvalho de Melo - Improve -user-regs/intr-regs suggestions to overcome errors. perf annotate: Jin Yao: - Remove hist__account_cycles() from callback, speeding up branch processing (perf record -b). perf stat: - Add a 'percore' event qualifier, e.g.: -e cpu/event=0,umask=0x3,percore=1/, that sums up the event counts for both hardware threads in a core. We can already do this with --per-core, but it's often useful to do this together with other metrics that are collected per hardware thread. I.e. now its possible to do this per-event, and have it mixed with other events not aggregated by core. core libraries: Donald Yandt: - Check for errors when doing fgets(/proc/version). Jiri Olsa: - Speed up report for perf compiled with linbunwind. tools headers: Arnaldo Carvalho de Melo - Update memcpy_64.S, x86's kvm.h and pt_regs.h. arm64: Florian Fainelli: - Map Brahma-B53 CPUID to cortex-a53 events. - Add Cortex-A57 and Cortex-A72 events. csky: Mao Han: - Add DWARF register mappings for libdw, allowing --call-graph=dwarf to work on the C-SKY arch. x86: Andi Kleen/Kan Liang: - Add support for recording and printing XMM registers, available, for instance, on Icelake. Kan Liang: - Add uncore_upi (Intel's "Ultra Path Interconnect" events) JSON support. UPI replaced the Intel QuickPath Interconnect (QPI) in Xeon Skylake-SP. Intel PT: Adrian Hunter . Fix instructions sampling rate. . Timestamp fixes. . Improve exported-sql-viewer GUI, allowing, for instance, to copy'n'paste the trees, useful for e-mailing. Documentation: Thomas Richter: - Add description for 'perf --debug stderr=1', which redirects stderr to stdout. libtraceevent: Tzvetomir Stoyanov: - Add man pages for the various APIs. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
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+libtraceevent(3)
+================
+
+NAME
+----
+tep_register_event_handler, tep_unregister_event_handler - Register /
+unregisters a callback function to parse an event information.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+enum *tep_reg_handler* {
+ _TEP_REGISTER_SUCCESS_,
+ _TEP_REGISTER_SUCCESS_OVERWRITE_,
+};
+
+int *tep_register_event_handler*(struct tep_handle pass:[*]_tep_, int _id_, const char pass:[*]_sys_name_, const char pass:[*]_event_name_, tep_event_handler_func _func_, void pass:[*]_context_);
+int *tep_unregister_event_handler*(struct tep_handle pass:[*]tep, int id, const char pass:[*]sys_name, const char pass:[*]event_name, tep_event_handler_func func, void pass:[*]_context_);
+
+typedef int (*pass:[*]tep_event_handler_func*)(struct trace_seq pass:[*]s, struct tep_record pass:[*]record, struct tep_event pass:[*]event, void pass:[*]context);
+--
+
+DESCRIPTION
+-----------
+The _tep_register_event_handler()_ function registers a handler function,
+which is going to be called to parse the information for a given event.
+The _tep_ argument is the trace event parser context. The _id_ argument is
+the id of the event. The _sys_name_ argument is the name of the system,
+the event belongs to. The _event_name_ argument is the name of the event.
+If _id_ is >= 0, it is used to find the event, otherwise _sys_name_ and
+_event_name_ are used. The _func_ is a pointer to the function, which is going
+to be called to parse the event information. The _context_ argument is a pointer
+to the context data, which will be passed to the _func_. If a handler function
+for the same event is already registered, it will be overridden with the new
+one. This mechanism allows a developer to override the parsing of a given event.
+If for some reason the default print format is not sufficient, the developer
+can register a function for an event to be used to parse the data instead.
+
+The _tep_unregister_event_handler()_ function unregisters the handler function,
+previously registered with _tep_register_event_handler()_. The _tep_ argument
+is the trace event parser context. The _id_, _sys_name_, _event_name_, _func_,
+and _context_ are the same arguments, as when the callback function _func_ was
+registered.
+
+The _tep_event_handler_func_ is the type of the custom event handler
+function. The _s_ argument is the trace sequence, it can be used to create a
+custom string, describing the event. A _record_ to get the event from is passed
+as input parameter and also the _event_ - the handle to the record's event. The
+_context_ is custom context, set when the custom event handler is registered.
+
+RETURN VALUE
+------------
+The _tep_register_event_handler()_ function returns _TEP_REGISTER_SUCCESS_
+if the new handler is registered successfully or
+_TEP_REGISTER_SUCCESS_OVERWRITE_ if an existing handler is overwritten.
+If there is not enough memory to complete the registration,
+TEP_ERRNO__MEM_ALLOC_FAILED is returned.
+
+The _tep_unregister_event_handler()_ function returns 0 if _func_ was removed
+successful or, -1 if the event was not found.
+
+The _tep_event_handler_func_ should return -1 in case of an error,
+or 0 otherwise.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+#include <trace-seq.h>
+...
+struct tep_handle *tep = tep_alloc();
+...
+int timer_expire_handler(struct trace_seq *s, struct tep_record *record,
+ struct tep_event *event, void *context)
+{
+ trace_seq_printf(s, "hrtimer=");
+
+ if (tep_print_num_field(s, "0x%llx", event, "timer", record, 0) == -1)
+ tep_print_num_field(s, "0x%llx", event, "hrtimer", record, 1);
+
+ trace_seq_printf(s, " now=");
+
+ tep_print_num_field(s, "%llu", event, "now", record, 1);
+
+ tep_print_func_field(s, " function=%s", event, "function", record, 0);
+
+ return 0;
+}
+...
+ int ret;
+
+ ret = tep_register_event_handler(tep, -1, "timer", "hrtimer_expire_entry",
+ timer_expire_handler, NULL);
+ if (ret < 0) {
+ char buf[32];
+
+ tep_strerror(tep, ret, buf, 32)
+ printf("Failed to register handler for hrtimer_expire_entry: %s\n", buf);
+ } else {
+ switch (ret) {
+ case TEP_REGISTER_SUCCESS:
+ printf ("Registered handler for hrtimer_expire_entry\n");
+ break;
+ case TEP_REGISTER_SUCCESS_OVERWRITE:
+ printf ("Overwrote handler for hrtimer_expire_entry\n");
+ break;
+ }
+ }
+...
+ ret = tep_unregister_event_handler(tep, -1, "timer", "hrtimer_expire_entry",
+ timer_expire_handler, NULL);
+ if ( ret )
+ printf ("Failed to unregister handler for hrtimer_expire_entry\n");
+
+--
+
+FILES
+-----
+[verse]
+--
+*event-parse.h*
+ Header file to include in order to have access to the library APIs.
+*trace-seq.h*
+ Header file to include in order to have access to trace sequences
+ related APIs. Trace sequences are used to allow a function to call
+ several other functions to create a string of data to use.
+*-ltraceevent*
+ Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+_libtraceevent(3)_, _trace-cmd(1)_
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
+--
+REPORTING BUGS
+--------------
+Report bugs to <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtraceevent is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git