perf auxtrace: Add itrace A option to approximate IPC

Add an option to specify that synthesized IPC can be approximate, rather
than completely accurate.
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/20211027080334.365596-3-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/itrace.txt

@@ -20,6 +20,7 @@
 		L	synthesize last branch entries on existing event records
 		s       skip initial number of events
 		q	quicker (less detailed) decoding
+		A	approximate IPC
 		Z	prefer to ignore timestamps (so-called "timeless" decoding)
 
 	The default is all events i.e. the same as --itrace=ibxwpe,

tools/perf/util/auxtrace.c

@@ -1564,6 +1564,9 @@ int itrace_do_parse_synth_opts(struct itrace_synth_opts *synth_opts,
 		case 'q':
 			synth_opts->quick += 1;
 			break;
+		case 'A':
+			synth_opts->approx_ipc = true;
+			break;
 		case 'Z':
 			synth_opts->timeless_decoding = true;
 			break;

tools/perf/util/auxtrace.h

@@ -84,6 +84,7 @@ enum itrace_period_type {
  * @thread_stack: feed branches to the thread_stack
  * @last_branch: add branch context to 'instruction' events
  * @add_last_branch: add branch context to existing event records
+ * @approx_ipc: approximate IPC
  * @flc: whether to synthesize first level cache events
  * @llc: whether to synthesize last level cache events
  * @tlb: whether to synthesize TLB events
@@ -127,6 +128,7 @@ struct itrace_synth_opts {
 	bool			thread_stack;
 	bool			last_branch;
 	bool			add_last_branch;
+	bool			approx_ipc;
 	bool			flc;
 	bool			llc;
 	bool			tlb;
@@ -649,6 +651,7 @@ bool auxtrace__evsel_is_auxtrace(struct perf_session *session,
 "				L[len]:			synthesize last branch entries on existing event records\n" \
 "				sNUMBER:    		skip initial number of events\n"		\
 "				q:			quicker (less detailed) decoding\n" \
+"				A:			approximate IPC\n" \
 "				Z:			prefer to ignore timestamps (so-called \"timeless\" decoding)\n" \
 "				PERIOD[ns|us|ms|i|t]:   specify period to sample stream\n" \
 "				concatenate multiple options. Default is ibxwpe or cewp\n"