diff options
| author | Adrian Hunter <adrian.hunter@intel.com> | 2021-07-01 20:51:32 +0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2021-07-07 11:40:56 -0300 |
| commit | b4b046ff9e3410593db7b35326cf696810af8f4f (patch) | |
| tree | e70198ffe60371758acf44486501fc2560c1c82e /tools/perf/Documentation/perf-config.txt | |
| parent | 493be70ac3cdf016d3b608a6c3c0048242a68925 (diff) | |
perf intel-pt: Add a config for max loops without consuming a packet
The Intel PT decoder limits the number of unconditional branches (e.g.
jmps) decoded without consuming any trace packets. Generally, a loop
needs a conditional branch which generates a TNT packet, whereas a "ret"
instruction will generate a TIP or TNT packet. So exceeding the limit is
assumed to be a never-ending loop, which can happen if there has been a
decoding error putting the decoder at the wrong place in the code.
Up until now, the limit of 10000 has been enough but some analytic
purposes have been reported to exceed that.
Increase the limit to 100000, and make it configurable via perf config
intel-pt.max-loops. Also amend the "Never-ending loop" message to
mention the configuration entry.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20210701175132.3977-1-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/Documentation/perf-config.txt')
| -rw-r--r-- | tools/perf/Documentation/perf-config.txt | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt index b0872c801866..3bb75c1f25e8 100644 --- a/tools/perf/Documentation/perf-config.txt +++ b/tools/perf/Documentation/perf-config.txt @@ -706,6 +706,12 @@ intel-pt.*:: If set, Intel PT decoder will set the mispred flag on all branches. + intel-pt.max-loops:: + If set and non-zero, the maximum number of unconditional + branches decoded without consuming any trace packets. If + the maximum is exceeded there will be a "Never-ending loop" + error. The default is 100000. + auxtrace.*:: auxtrace.dumpdir:: |