perf dlfilter: Add dlfilter-show-cycles

Add a new dlfilter to show cycles.

Cycle counts are accumulated per CPU (or per thread if CPU is not recorded)
from IPC information, and printed together with the change since the last
print, at the start of each line. Separate counts are kept for branches,
instructions or other events.

Note also, the itrace A option can be useful to provide higher granularity
cycle information.

Example:

  $ perf record -e intel_pt/cyc/u uname
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.044 MB perf.data ]
  $ perf script --itrace=A --call-trace --dlfilter dlfilter-show-cycles.so --deltatime | head
         0                   perf-exec  8509 [001]     0.000000000:  psb offs: 0
         0                   perf-exec  8509 [001]     0.000000000:  cbr: 42 freq: 4219 MHz (156%)
       833        833            uname  8509 [001]     0.000047689: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )        _start
       833                       uname  8509 [001]     0.000003261: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )            _dl_start
      2015       1182            uname  8509 [001]     0.000000282: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )            _dl_start
      2676        661            uname  8509 [001]     0.000002629: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )            _dl_start
      3612        936            uname  8509 [001]     0.000001232: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )            _dl_start
      4579        967            uname  8509 [001]     0.000002519: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )            _dl_start
      6145       1566            uname  8509 [001]     0.000001050: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )                _dl_setup_hash
      6239         94            uname  8509 [001]     0.000000023: (/usr/lib/x86_64-linux-gnu/ld-2.31.so              )                _dl_sysdep_start

Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20211027080334.365596-5-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 8914335db84b..c792fa7b59d3 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -164,7 +164,9 @@ actual number of cycles increases even though the cycles reported does not.
 The number of instructions is known, but if IPC is reported, cycles can be too
 low and so IPC is too high.  Note that inaccuracy decreases as the period of
 sampling increases i.e. if the number of cycles is too low by a small amount,
-that becomes less significant if the number of cycles is large.
+that becomes less significant if the number of cycles is large.  It may also be
+useful to use the 'A' option in conjunction with dlfilter-show-cycles.so to
+provide higher granularity cycle information.
 
 Also note that the IPC instruction count may or may not include the current
 instruction.  If the cycle count is associated with an asynchronous branch
@@ -1082,6 +1084,21 @@ The Z option is equivalent to having recorded a trace without TSC
 decoding a trace of a virtual machine.
 
 
+dlfilter-show-cycles.so
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Cycles can be displayed using dlfilter-show-cycles.so in which case the itrace A
+option can be useful to provide higher granularity cycle information:
+
+	perf script --itrace=A --call-trace --dlfilter dlfilter-show-cycles.so
+
+To see a list of dlfilters:
+
+	perf script -v --list-dlfilters
+
+See also linkperf:perf-dlfilters[1]
+
+
 dump option
 ~~~~~~~~~~~