[PATCH] perf report/annotate: Add option to specify a CPU range

[Anton Blanchard]

Add an option to perf report and perf annotate 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>.

Signed-off-by: Anton Blanchard <anton@xxxxxxxxx>
---

I capped it at MAX_NR_CPUS to avoid having to dynamically allocate
cpu_bitmap, but we could do that if the extra complexity is worth it.

Index: linux-2.6-tip/tools/perf/builtin-report.c
===================================================================
--- linux-2.6-tip.orig/tools/perf/builtin-report.c	2011-06-29 09:01:46.209676867 +1000
+++ linux-2.6-tip/tools/perf/builtin-report.c	2011-06-29 14:53:26.131226181 +1000
@@ -33,6 +33,9 @@
 #include "util/sort.h"
 #include "util/hist.h"
 
+#include <linux/bitmap.h>
+#include "util/cpumap.h"
+
 static char		const *input_name = "perf.data";
 
 static bool		force, use_tui, use_stdio;
@@ -48,6 +51,9 @@ static const char	*pretty_printing_style
 static char		callchain_default_opt[] = "fractal,0.5";
 static symbol_filter_t	annotate_init;
 
+static const char	*cpu_list;
+static DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
+
 static int perf_session__add_hist_entry(struct perf_session *session,
 					struct addr_location *al,
 					struct perf_sample *sample,
@@ -116,6 +122,9 @@ static int process_sample_event(union pe
 	if (al.filtered || (hide_unresolved && al.sym == NULL))
 		return 0;
 
+	if (cpu_list && !test_bit(sample->cpu, cpu_bitmap))
+		return 0;
+
 	if (al.map != NULL)
 		al.map->dso->hit = 1;
 
@@ -455,6 +464,7 @@ static const struct option options[] = {
 		    "Only display entries resolved to a symbol"),
 	OPT_STRING(0, "symfs", &symbol_conf.symfs, "directory",
 		    "Look for files with symbols relative to this directory"),
+	OPT_STRING('c', "cpu", &cpu_list, "cpu", "list of cpus to profile"),
 	OPT_END()
 };
 
@@ -501,6 +511,23 @@ int cmd_report(int argc, const char **ar
 
 	setup_sorting(report_usage, options);
 
+	if (cpu_list) {
+		int i;
+		struct cpu_map *map = cpu_map__new(cpu_list);
+
+		for (i = 0; i < map->nr; i++) {
+			int cpu = map->map[i];
+
+			if (cpu >= MAX_NR_CPUS) {
+				fprintf(stderr, "Requested CPU %d too large, "
+					"consider raising MAX_NR_CPUS\n", cpu);
+				return -1;
+			}
+
+			set_bit(cpu, cpu_bitmap);
+		}
+	}
+
 	if (parent_pattern != default_parent_pattern) {
 		if (sort_dimension__add("parent") < 0)
 			return -1;
Index: linux-2.6-tip/tools/perf/builtin-annotate.c
===================================================================
--- linux-2.6-tip.orig/tools/perf/builtin-annotate.c	2011-06-29 09:01:46.199676692 +1000
+++ linux-2.6-tip/tools/perf/builtin-annotate.c	2011-06-29 09:01:56.519857004 +1000
@@ -28,6 +28,9 @@
 #include "util/hist.h"
 #include "util/session.h"
 
+#include <linux/bitmap.h>
+#include "util/cpumap.h"
+
 static char		const *input_name = "perf.data";
 
 static bool		force, use_tui, use_stdio;
@@ -38,6 +41,9 @@ static bool		print_line;
 
 static const char *sym_hist_filter;
 
+static const char	*cpu_list;
+static DECLARE_BITMAP(cpu_bitmap, MAX_NR_CPUS);
+
 static int perf_evlist__add_sample(struct perf_evlist *evlist,
 				   struct perf_sample *sample,
 				   struct perf_evsel *evsel,
@@ -90,6 +96,9 @@ static int process_sample_event(union pe
 		return -1;
 	}
 
+	if (cpu_list && !test_bit(sample->cpu, cpu_bitmap))
+		return 0;
+
 	if (!al.filtered &&
 	    perf_evlist__add_sample(session->evlist, sample, evsel, &al)) {
 		pr_warning("problem incrementing symbol count, "
@@ -252,6 +261,7 @@ static const struct option options[] = {
 		    "print matching source lines (may be slow)"),
 	OPT_BOOLEAN('P', "full-paths", &full_paths,
 		    "Don't shorten the displayed pathnames"),
+	OPT_STRING('c', "cpu", &cpu_list, "cpu", "list of cpus to profile"),
 	OPT_END()
 };
 
@@ -274,6 +284,23 @@ int cmd_annotate(int argc, const char **
 
 	setup_sorting(annotate_usage, options);
 
+	if (cpu_list) {
+		int i;
+		struct cpu_map *map = cpu_map__new(cpu_list);
+
+		for (i = 0; i < map->nr; i++) {
+			int cpu = map->map[i];
+
+			if (cpu >= MAX_NR_CPUS) {
+				fprintf(stderr, "Requested CPU %d too large, "
+					"consider raising MAX_NR_CPUS\n", cpu);
+				return -1;
+			}
+
+			set_bit(cpu, cpu_bitmap);
+		}
+	}
+
 	if (argc) {
 		/*
 		 * Special case: if there's an argument left then assume tha
--
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