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authorIngo Molnar <mingo@kernel.org>2019-05-18 11:24:43 +0300
committerIngo Molnar <mingo@kernel.org>2019-05-18 11:24:43 +0300
commit62e1c09418fc16d27720b128275cac61367e2c1b (patch)
tree4759aa6662b1398e2b93696ace58f6f309722b06 /tools/lib/traceevent/Documentation/libtraceevent-commands.txt
parent01be377c62210a8d8fef35be906f9349591bb7cd (diff)
parent4fc4d8dfa056dfd48afe73b9ea3b7570ceb80b9c (diff)
downloadlinux-62e1c09418fc16d27720b128275cac61367e2c1b.tar.xz
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_comm, tep_override_comm, tep_pid_is_registered,
+tep_data_comm_from_pid, tep_data_pid_from_comm, tep_cmdline_pid -
+Manage pid to process name mappings.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+int *tep_register_comm*(struct tep_handle pass:[*]_tep_, const char pass:[*]_comm_, int _pid_);
+int *tep_override_comm*(struct tep_handle pass:[*]_tep_, const char pass:[*]_comm_, int _pid_);
+bool *tep_is_pid_registered*(struct tep_handle pass:[*]_tep_, int _pid_);
+const char pass:[*]*tep_data_comm_from_pid*(struct tep_handle pass:[*]_pevent_, int _pid_);
+struct cmdline pass:[*]*tep_data_pid_from_comm*(struct tep_handle pass:[*]_pevent_, const char pass:[*]_comm_, struct cmdline pass:[*]_next_);
+int *tep_cmdline_pid*(struct tep_handle pass:[*]_pevent_, struct cmdline pass:[*]_cmdline_);
+--
+
+DESCRIPTION
+-----------
+These functions can be used to handle the mapping between pid and process name.
+The library builds a cache of these mappings, which is used to display the name
+of the process, instead of its pid. This information can be retrieved from
+tracefs/saved_cmdlines file.
+
+The _tep_register_comm()_ function registers a _pid_ / process name mapping.
+If a command with the same _pid_ is already registered, an error is returned.
+The _pid_ argument is the process ID, the _comm_ argument is the process name,
+_tep_ is the event context. The _comm_ is duplicated internally.
+
+The _tep_override_comm()_ function registers a _pid_ / process name mapping.
+If a process with the same pid is already registered, the process name string is
+udapted with the new one. The _pid_ argument is the process ID, the _comm_
+argument is the process name, _tep_ is the event context. The _comm_ is
+duplicated internally.
+
+The _tep_is_pid_registered()_ function checks if a pid has a process name
+mapping registered. The _pid_ argument is the process ID, _tep_ is the event
+context.
+
+The _tep_data_comm_from_pid()_ function returns the process name for a given
+pid. The _pid_ argument is the process ID, _tep_ is the event context.
+The returned string should not be freed, but will be freed when the _tep_
+handler is closed.
+
+The _tep_data_pid_from_comm()_ function returns a pid for a given process name.
+The _comm_ argument is the process name, _tep_ is the event context.
+The argument _next_ is the cmdline structure to search for the next pid.
+As there may be more than one pid for a given process, the result of this call
+can be passed back into a recurring call in the _next_ parameter, to search for
+the next pid. If _next_ is NULL, it will return the first pid associated with
+the _comm_. The function performs a linear search, so it may be slow.
+
+The _tep_cmdline_pid()_ function returns the pid associated with a given
+_cmdline_. The _tep_ argument is the event context.
+
+RETURN VALUE
+------------
+_tep_register_comm()_ function returns 0 on success. In case of an error -1 is
+returned and errno is set to indicate the cause of the problem: ENOMEM, if there
+is not enough memory to duplicate the _comm_ or EEXIST if a mapping for this
+_pid_ is already registered.
+
+_tep_override_comm()_ function returns 0 on success. In case of an error -1 is
+returned and errno is set to indicate the cause of the problem: ENOMEM, if there
+is not enough memory to duplicate the _comm_.
+
+_tep_is_pid_registered()_ function returns true if the _pid_ has a process name
+mapped to it, false otherwise.
+
+_tep_data_comm_from_pid()_ function returns the process name as string, or the
+string "<...>" if there is no mapping for the given pid.
+
+_tep_data_pid_from_comm()_ function returns a pointer to a struct cmdline, that
+holds a pid for a given process, or NULL if none is found. This result can be
+passed back into a recurring call as the _next_ parameter of the function.
+
+_tep_cmdline_pid()_ functions returns the pid for the give cmdline. If _cmdline_
+ is NULL, then -1 is returned.
+
+EXAMPLE
+-------
+The following example registers pid for command "ls", in context of event _tep_
+and performs various searches for pid / process name mappings:
+[source,c]
+--
+#include <event-parse.h>
+...
+int ret;
+int ls_pid = 1021;
+struct tep_handle *tep = tep_alloc();
+...
+ ret = tep_register_comm(tep, "ls", ls_pid);
+ if (ret != 0 && errno == EEXIST)
+ ret = tep_override_comm(tep, "ls", ls_pid);
+ if (ret != 0) {
+ /* Failed to register pid / command mapping */
+ }
+...
+ if (tep_is_pid_registered(tep, ls_pid) == 0) {
+ /* Command mapping for ls_pid is not registered */
+ }
+...
+ const char *comm = tep_data_comm_from_pid(tep, ls_pid);
+ if (comm) {
+ /* Found process name for ls_pid */
+ }
+...
+ int pid;
+ struct cmdline *cmd = tep_data_pid_from_comm(tep, "ls", NULL);
+ while (cmd) {
+ pid = tep_cmdline_pid(tep, cmd);
+ /* Found pid for process "ls" */
+ cmd = tep_data_pid_from_comm(tep, "ls", cmd);
+ }
+--
+FILES
+-----
+[verse]
+--
+*event-parse.h*
+ Header file to include in order to have access to the library APIs.
+*-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