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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-header_page.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_get_header_page_size, tep_get_header_timestamp_size, tep_is_old_format -
+Get the data stored in the header page, in kernel context.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+
+int *tep_get_header_page_size*(struct tep_handle pass:[*]_tep_);
+int *tep_get_header_timestamp_size*(struct tep_handle pass:[*]_tep_);
+bool *tep_is_old_format*(struct tep_handle pass:[*]_tep_);
+--
+DESCRIPTION
+-----------
+These functions retrieve information from kernel context, stored in tracefs
+events/header_page. Old kernels do not have header page info, so default values
+from user space context are used.
+
+The _tep_get_header_page_size()_ function returns the size of a long integer,
+in kernel context. The _tep_ argument is trace event parser context.
+This information is retrieved from tracefs events/header_page, "commit" field.
+
+The _tep_get_header_timestamp_size()_ function returns the size of timestamps,
+in kernel context. The _tep_ argument is trace event parser context. This
+information is retrieved from tracefs events/header_page, "timestamp" field.
+
+The _tep_is_old_format()_ function returns true if the kernel predates
+the addition of events/header_page, otherwise it returns false.
+
+RETURN VALUE
+------------
+The _tep_get_header_page_size()_ function returns the size of a long integer,
+in bytes.
+
+The _tep_get_header_timestamp_size()_ function returns the size of timestamps,
+in bytes.
+
+The _tep_is_old_format()_ function returns true, if an old kernel is used to
+generate the tracing data, which has no event/header_page. If the kernel is new,
+or _tep_ is NULL, false is returned.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+...
+struct tep_handle *tep = tep_alloc();
+...
+ int longsize;
+ int timesize;
+ bool old;
+
+ longsize = tep_get_header_page_size(tep);
+ timesize = tep_get_header_timestamp_size(tep);
+ old = tep_is_old_format(tep);
+
+ printf ("%s kernel is used to generate the tracing data.\n",
+ old?"Old":"New");
+ printf("The size of a long integer is %d bytes.\n", longsize);
+ printf("The timestamps size is %d bytes.\n", timesize);
+...
+--
+
+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