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authorAdrian Hunter <adrian.hunter@intel.com>2020-07-10 18:11:03 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2020-08-06 15:02:14 +0300
commit7c1b16ba0e26e6802d80c99c92529f29bcdcea25 (patch)
tree788eca05bf50ec627258a751dcaaa27b3388a2e7 /tools/perf/Documentation
parent51971536ef53478ec92cd9e8249048743169df22 (diff)
downloadlinux-7c1b16ba0e26e6802d80c99c92529f29bcdcea25.tar.xz
perf intel-pt: Add support for decoding FUP/TIP only
Use the new itrace 'q' option to add support for a mode of decoding that ignores TNT, does not walk object code, but gets the ip from FUP and TIP packets. Example: $ perf record -e intel_pt//u grep -rI pudding drivers [ perf record: Woken up 52 times to write data ] [ perf record: Captured and wrote 57.870 MB perf.data ] $ time perf script --itrace=bi | wc -l 58948289 real 1m23.863s user 1m23.251s sys 0m7.452s $ time perf script --itrace=biq | wc -l 3385694 real 0m4.453s user 0m4.455s sys 0m0.328s Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Reviewed-by: Andi Kleen <ak@linux.intel.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Link: http://lore.kernel.org/lkml/20200710151104.15137-12-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/Documentation')
-rw-r--r--tools/perf/Documentation/perf-intel-pt.txt31
1 files changed, 31 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-intel-pt.txt b/tools/perf/Documentation/perf-intel-pt.txt
index 4666e4a83615..f9fe4a4040ba 100644
--- a/tools/perf/Documentation/perf-intel-pt.txt
+++ b/tools/perf/Documentation/perf-intel-pt.txt
@@ -825,6 +825,7 @@ The letters are:
l synthesize last branch entries (use with i or x)
L synthesize last branch entries on existing event records
s skip initial number of events
+ q quicker (less detailed) decoding
"Instructions" events look like they were recorded by "perf record -e
instructions".
@@ -969,6 +970,36 @@ at the beginning. This is useful to ignore initialization code.
skips the first million instructions.
+The q option changes the way the trace is decoded. The decoding is much faster
+but much less detailed. Specifically, with the q option, the decoder does not
+decode TNT packets, and does not walk object code, but gets the ip from FUP and
+TIP packets. The q option can be used with the b and i options but the period
+is not used. The q option decodes more quickly, but is useful only if the
+control flow of interest is represented or indicated by FUP, TIP, TIP.PGE, or
+TIP.PGD packets (refer below). However the q option could be used to find time
+ranges that could then be decoded fully using the --time option.
+
+What will *not* be decoded with the (single) q option:
+
+ - direct calls and jmps
+ - conditional branches
+ - non-branch instructions
+
+What *will* be decoded with the (single) q option:
+
+ - asynchronous branches such as interrupts
+ - indirect branches
+ - function return target address *if* the noretcomp config term (refer
+ config terms section) was used
+ - start of (control-flow) tracing
+ - end of (control-flow) tracing, if it is not out of context
+ - power events, ptwrite, transaction start and abort
+ - instruction pointer associated with PSB packets
+
+Note the q option does not specify what events will be synthesized e.g. the p
+option must be used also to show power events.
+
+
dump option
~~~~~~~~~~~