perf report/annotate/script: Add option to specify a CPU range

Add an option to perf report/annotate/script to specify which
CPUs to operate on. This enables us to take a single system wide
profile and analyse each CPU (or group of CPUs) in isolation.

This was useful when profiling a multiprocess workload where the
bottleneck was on one CPU but this was hidden in the overall
profile. Per process and per thread breakdowns didn't help
because multiple processes were running on each CPU and no
single process consumed an entire CPU.

The patch converts the list of CPUs returned by cpu_map__new
into a bitmap for fast lookup. I wanted to use -C to be
consistent with perf top/record/stat, but unfortunately perf
report already uses -C <comms>.

 v2: Incorporate suggestions from David Ahern:
	- Added -c to perf script
	- Check that SAMPLE_CPU is set when -c is used
	- Update documentation

 v3: Create perf_session__cpu_bitmap()

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Link: http://lkml.kernel.org/r/20110704215750.11647eb9@kryten
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 38 insertions, 0 deletions

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 558bcf9..080e533 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -12,6 +12,7 @@
 #include "session.h"
 #include "sort.h"
 #include "util.h"
+#include "cpumap.h"
 
 static int perf_session__open(struct perf_session *self, bool force)
 {
@@ -1282,3 +1283,40 @@ void perf_session__print_ip(union perf_event *event,
 		}
 	}
 }
+
+int perf_session__cpu_bitmap(struct perf_session *session,
+			     const char *cpu_list, unsigned long *cpu_bitmap)
+{
+	int i;
+	struct cpu_map *map;
+
+	for (i = 0; i < PERF_TYPE_MAX; ++i) {
+		struct perf_evsel *evsel;
+
+		evsel = perf_session__find_first_evtype(session, i);
+		if (!evsel)
+			continue;
+
+		if (!(evsel->attr.sample_type & PERF_SAMPLE_CPU)) {
+			pr_err("File does not contain CPU events. "
+			       "Remove -c option to proceed.\n");
+			return -1;
+		}
+	}
+
+	map = cpu_map__new(cpu_list);
+
+	for (i = 0; i < map->nr; i++) {
+		int cpu = map->map[i];
+
+		if (cpu >= MAX_NR_CPUS) {
+			pr_err("Requested CPU %d too large. "
+			       "Consider raising MAX_NR_CPUS\n", cpu);
+			return -1;
+		}
+
+		set_bit(cpu, cpu_bitmap);
+	}
+
+	return 0;
+}