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linux/tools/perf/Documentation
Masami Hiramatsu f8bffbf122 perf probe: Support $params special probe argument
$params is similar to $vars but matches only function parameters not
local variables.

Thus, this is useful for tracing function parameter changing or tracing
function call with parameters.

Testing it:

 # perf probe tcp_sendmsg '$params'
 Added new event:
  probe:tcp_sendmsg    (on tcp_sendmsg with $params)

 You can now use it in all perf tools, such as:

	perf record -e probe:tcp_sendmsg -aR sleep 1

 # perf probe -l
  probe:tcp_sendmsg    (on tcp_sendmsg@acme/git/linux/net/ipv4/tcp.c with iocb sk msg size)
 # perf record -a -e probe:*
 press some random letters to generate TCP (sshd) traffic...

 ^C[ perf record: Woken up 1 times to write data ]
 [ perf record: Captured and wrote 0.223 MB perf.data (6 samples) ]

 # perf script
   sshd 6385 [2] 3.907529: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24
   sshd 6385 [2] 4.138973: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24
   sshd 6385 [2] 4.378966: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24
   sshd 6385 [2] 4.603681: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24
   sshd 6385 [2] 4.818455: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24
   sshd 6385 [2] 5.043603: probe:tcp_sendmsg: iocb=0xffff8800ac4cfe70 sk=0xffff88042196c140 msg=0xffff8800ac4cfda8 size=0x24
 # cat /sys/kernel/debug/tracing/events/probe/tcp_sendmsg/format
 name: tcp_sendmsg
 ID: 1927
 format:
   field:unsigned short common_type;	offset:0;	size:2;	signed:0;
   field:unsigned char common_flags;	offset:2;	size:1;	signed:0;
   field:unsigned char common_preempt_count;	offset:3;	size:1;	signed:0;
   field:int common_pid;	offset:4;	size:4;	signed:1;

   field:unsigned long __probe_ip;	offset:8;	size:8;	signed:0;
   field:u64 iocb;	offset:16;	size:8;	signed:0;
   field:u64 sk;	offset:24;	size:8;	signed:0;
   field:u64 msg;	offset:32;	size:8;	signed:0;
   field:u64 size;	offset:40;	size:8;	signed:0;

 print fmt: "(%lx) iocb=0x%Lx sk=0x%Lx msg=0x%Lx size=0x%Lx", REC->__probe_ip, REC->iocb, REC->sk, REC->msg, REC->size
 #

 Do some system wide tracing of this probe + write syscalls:

 # perf trace -e write --ev probe:* --filter-pids 6385
  462.612 (0.010 ms): bash/19153 write(fd: 1</dev/pts/1>, buf: 0x7f7556c78000, count: 29               ) = 29
  462.701 (0.027 ms): sshd/19152 write(fd: 3<socket:[63117]>, buf: 0x7f78dd12e160, count: 68           ) ...
  462.701 (        ): probe:tcp_sendmsg:(ffffffff8163db30) iocb=0xffff8803ebec7e70 sk=0xffff88042196ab80 msg=0xffff8803ebec7da8 size=0x44)
  462.710 (0.035 ms): sshd/19152  ... [continued]: write()) = 68
  462.787 (0.009 ms): bash/19153 write(fd: 2</dev/pts/1>, buf: 0x7f7556c77000, count: 22               ) = 22
  462.865 (0.002 ms): sshd/19152 write(fd: 3<socket:[63117]>, buf: 0x7f78dd12e160, count: 68           ) ...
  462.865 (        ): probe:tcp_sendmsg:(ffffffff8163db30) iocb=0xffff8803ebec7e70 sk=0xffff88042196ab80 msg=0xffff8803ebec7da8 size=0x44)
  462.873 (0.010 ms): sshd/19152  ... [continued]: write()) = 68

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150506124653.4961.59806.stgit@localhost.localdomain
[ Add some examples to the changelog message showing how to use it ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-05-08 16:05:03 -03:00
..
android.txt perf tools: Add info about cross compiling for Android ARM 2012-10-31 12:17:49 -02:00
asciidoc.conf perf_counter tools: Move from Documentation/perf_counter/ to tools/perf/ 2009-06-06 20:33:43 +02:00
Build.txt perf build: Add build documentation 2015-02-12 17:53:00 -03:00
callchain-overhead-calculation.txt perf tools: Document --children option in more detail 2015-04-29 10:38:06 -03:00
examples.txt perf record: Remove -f/--force option 2013-07-08 17:37:25 -03:00
jit-interface.txt perf symbols: Add description of JIT interface 2012-08-13 14:55:02 -03:00
Makefile perf tools: Implement summary output for 'make install' 2013-10-11 12:18:11 -03:00
manpage-1.72.xsl perf_counter tools: Move from Documentation/perf_counter/ to tools/perf/ 2009-06-06 20:33:43 +02:00
manpage-base.xsl perf_counter tools: Move from Documentation/perf_counter/ to tools/perf/ 2009-06-06 20:33:43 +02:00
manpage-bold-literal.xsl perf_counter tools: Move from Documentation/perf_counter/ to tools/perf/ 2009-06-06 20:33:43 +02:00
manpage-normal.xsl perf_counter tools: Move from Documentation/perf_counter/ to tools/perf/ 2009-06-06 20:33:43 +02:00
manpage-suppress-sp.xsl perf_counter tools: Move from Documentation/perf_counter/ to tools/perf/ 2009-06-06 20:33:43 +02:00
perf-annotate.txt perf annotate: Add basic support to event group view 2013-03-15 13:06:05 -03:00
perf-archive.txt perf archive: Remove duplicated 'runs' in man page 2013-12-09 15:21:45 -03:00
perf-bench.txt perf bench: Add --repeat option 2014-06-19 16:13:15 -03:00
perf-buildid-cache.txt perf buildid-cache: Add --purge FILE to remove all caches of FILE 2015-02-27 15:52:33 -03:00
perf-buildid-list.txt perf report: Accept fifos as input file 2011-12-23 17:01:03 -02:00
perf-data.txt perf data: Add perf data to CTF conversion support 2015-02-25 16:13:12 -03:00
perf-diff.txt perf diff: Add kallsyms option 2015-03-24 13:01:54 -03:00
perf-evlist.txt perf evlist: Add --group option 2013-01-31 13:07:49 -03:00
perf-help.txt perf_counter tools: Move from Documentation/perf_counter/ to tools/perf/ 2009-06-06 20:33:43 +02:00
perf-inject.txt perf auxtrace: Add option to synthesize events for transactions 2015-05-05 18:12:55 -03:00
perf-kmem.txt perf kmem: Add --live option for current allocation stat 2015-05-04 13:34:47 -03:00
perf-kvm.txt perf Documentation: Fix typos in perf/Documentation 2014-10-15 17:39:02 -03:00
perf-list.txt perf tools: Add 'I' event modifier for exclude_idle bit 2015-04-08 11:00:16 -03:00
perf-lock.txt perf lock: Account for lock average wait time 2013-10-09 11:24:01 -03:00
perf-mem.txt perf mem: Enable sampling loads and stores simultaneously 2015-01-21 13:24:31 -03:00
perf-probe.txt perf probe: Support $params special probe argument 2015-05-08 16:05:03 -03:00
perf-record.txt perf record: Add AUX area tracing Snapshot Mode support 2015-05-05 18:13:01 -03:00
perf-report.txt perf auxtrace: Add option to synthesize events for transactions 2015-05-05 18:12:55 -03:00
perf-sched.txt perf report: Accept fifos as input file 2011-12-23 17:01:03 -02:00
perf-script-perl.txt perf Documentation: Fix typos in perf/Documentation 2014-10-15 17:39:02 -03:00
perf-script-python.txt perf Documentation: Fix typos in perf/Documentation 2014-10-15 17:39:02 -03:00
perf-script.txt perf auxtrace: Add option to synthesize events for transactions 2015-05-05 18:12:55 -03:00
perf-stat.txt perf tools: Document parameterized and symbolic events 2015-01-21 13:24:33 -03:00
perf-test.txt perf Documentation: Fix typos in perf/Documentation 2014-10-15 17:39:02 -03:00
perf-timechart.txt perf timechart: Add more options to IO mode 2014-07-10 00:22:54 +02:00
perf-top.txt perf tools: Document --children option in more detail 2015-04-29 10:38:06 -03:00
perf-trace.txt perf trace: Clarify that -e is about syscalls, not perf events in general 2015-04-29 10:38:04 -03:00
perf.txt perf data: Add perf data to CTF conversion support 2015-02-25 16:13:12 -03:00
perfconfig.example perf annotate browser: Read perf config file for settings 2012-05-29 22:06:30 -03:00