perf tests: Don't retest sections in "Object code reading"

We already only test each kcore map once, but on slow systems
(particularly with network filesystems) even the non-kcore maps are
slow.

The test can test the same objdump output over and over which only wastes
time. Generalize the skipping mechanism to track all DSOs and addresses
so that each section is only tested once.

On a fully loaded ARM Juno (simulating a parallel 'perf test' run) with
a network filesystem, the original runtime is:

  real  1m51.126s
  user  0m19.445s
  sys   1m15.431s

And the new runtime is:

  real  0m48.873s
  user  0m8.031s
  sys   0m32.353s

Committer testing:

  # perf test "code read"
   22: Object code reading          : Ok
  #

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: james-c-linaro

tools/perf/tests/code-reading.c

@@ -2,6 +2,7 @@
 #include <errno.h>
 #include <linux/kconfig.h>
 #include <linux/kernel.h>
+#include <linux/rbtree.h>
 #include <linux/types.h>
 #include <inttypes.h>
 #include <stdlib.h>
@@ -39,11 +40,64 @@
 #define BUFSZ	1024
 #define READLEN	128
 
-struct state {
-	u64 done[1024];
-	size_t done_cnt;
+struct tested_section {
+	struct rb_node rb_node;
+	u64 addr;
+	char path[PATH_MAX];
 };
 
+static bool tested_code_insert_or_exists(const char *path, u64 addr,
+					 struct rb_root *tested_sections)
+{
+	struct rb_node **node = &tested_sections->rb_node;
+	struct rb_node *parent = NULL;
+	struct tested_section *data;
+
+	while (*node) {
+		int cmp;
+
+		parent = *node;
+		data = rb_entry(*node, struct tested_section, rb_node);
+		cmp = strcmp(path, data->path);
+		if (!cmp) {
+			if (addr < data->addr)
+				cmp = -1;
+			else if (addr > data->addr)
+				cmp = 1;
+			else
+				return true; /* already tested */
+		}
+
+		if (cmp < 0)
+			node = &(*node)->rb_left;
+		else
+			node = &(*node)->rb_right;
+	}
+
+	data = zalloc(sizeof(*data));
+	if (!data)
+		return true;
+
+	data->addr = addr;
+	strlcpy(data->path, path, sizeof(data->path));
+	rb_link_node(&data->rb_node, parent, node);
+	rb_insert_color(&data->rb_node, tested_sections);
+	return false;
+}
+
+static void tested_sections__free(struct rb_root *root)
+{
+	while (!RB_EMPTY_ROOT(root)) {
+		struct rb_node *node = rb_first(root);
+		struct tested_section *ts = rb_entry(node,
+						     struct tested_section,
+						     rb_node);
+
+		rb_erase(node, root);
+		free(ts);
+	}
+}
+
 static size_t read_objdump_chunk(const char **line, unsigned char **buf,
 				 size_t *buf_len)
 {
@@ -316,13 +370,15 @@ static void dump_buf(unsigned char *buf, size_t len)
 }
 
 static int read_object_code(u64 addr, size_t len, u8 cpumode,
-			    struct thread *thread, struct state *state)
+			    struct thread *thread,
+			    struct rb_root *tested_sections)
 {
 	struct addr_location al;
 	unsigned char buf1[BUFSZ] = {0};
 	unsigned char buf2[BUFSZ] = {0};
 	size_t ret_len;
 	u64 objdump_addr;
+	u64 skip_addr;
 	const char *objdump_name;
 	char decomp_name[KMOD_DECOMP_LEN];
 	bool decomp = false;
@@ -350,6 +406,18 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 		goto out;
 	}
 
+	/*
+	 * Don't retest the same addresses. objdump struggles with kcore - try
+	 * each map only once even if the address is different.
+	 */
+	skip_addr = dso__is_kcore(dso) ? map__start(al.map) : al.addr;
+	if (tested_code_insert_or_exists(dso__long_name(dso), skip_addr,
+					 tested_sections)) {
+		pr_debug("Already tested %s @ %#"PRIx64" - skipping\n",
+			 dso__long_name(dso), skip_addr);
+		goto out;
+	}
+
 	pr_debug("On file address is: %#"PRIx64"\n", al.addr);
 
 	if (len > BUFSZ)
@@ -387,24 +455,6 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 		goto out;
 	}
 
-	/* objdump struggles with kcore - try each map only once */
-	if (dso__is_kcore(dso)) {
-		size_t d;
-
-		for (d = 0; d < state->done_cnt; d++) {
-			if (state->done[d] == map__start(al.map)) {
-				pr_debug("kcore map tested already");
-				pr_debug(" - skipping\n");
-				goto out;
-			}
-		}
-		if (state->done_cnt >= ARRAY_SIZE(state->done)) {
-			pr_debug("Too many kcore maps - skipping\n");
-			goto out;
-		}
-		state->done[state->done_cnt++] = map__start(al.map);
-	}
-
 	objdump_name = dso__long_name(dso);
 	if (dso__needs_decompress(dso)) {
 		if (dso__decompress_kmodule_path(dso, objdump_name,
@@ -471,9 +521,9 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 	return err;
 }
 
-static int process_sample_event(struct machine *machine,
-				struct evlist *evlist,
-				union perf_event *event, struct state *state)
+static int process_sample_event(struct machine *machine, struct evlist *evlist,
+				union perf_event *event,
+				struct rb_root *tested_sections)
 {
 	struct perf_sample sample;
 	struct thread *thread;
@@ -494,18 +544,20 @@ static int process_sample_event(struct machine *machine,
 		goto out;
 	}
 
-	ret = read_object_code(sample.ip, READLEN, sample.cpumode, thread, state);
+	ret = read_object_code(sample.ip, READLEN, sample.cpumode, thread,
+			       tested_sections);
 	thread__put(thread);
 out:
 	perf_sample__exit(&sample);
 	return ret;
 }
 
 static int process_event(struct machine *machine, struct evlist *evlist,
-			 union perf_event *event, struct state *state)
+			 union perf_event *event, struct rb_root *tested_sections)
 {
 	if (event->header.type == PERF_RECORD_SAMPLE)
-		return process_sample_event(machine, evlist, event, state);
+		return process_sample_event(machine, evlist, event,
+					    tested_sections);
 
 	if (event->header.type == PERF_RECORD_THROTTLE ||
 	    event->header.type == PERF_RECORD_UNTHROTTLE)
@@ -525,7 +577,7 @@ static int process_event(struct machine *machine, struct evlist *evlist,
 }
 
 static int process_events(struct machine *machine, struct evlist *evlist,
-			  struct state *state)
+			  struct rb_root *tested_sections)
 {
 	union perf_event *event;
 	struct mmap *md;
@@ -537,7 +589,7 @@ static int process_events(struct machine *machine, struct evlist *evlist,
 			continue;
 
 		while ((event = perf_mmap__read_event(&md->core)) != NULL) {
-			ret = process_event(machine, evlist, event, state);
+			ret = process_event(machine, evlist, event, tested_sections);
 			perf_mmap__consume(&md->core);
 			if (ret < 0)
 				return ret;
@@ -637,9 +689,7 @@ static int do_test_code_reading(bool try_kcore)
 			.uses_mmap   = true,
 		},
 	};
-	struct state state = {
-		.done_cnt = 0,
-	};
+	struct rb_root tested_sections = RB_ROOT;
 	struct perf_thread_map *threads = NULL;
 	struct perf_cpu_map *cpus = NULL;
 	struct evlist *evlist = NULL;
@@ -773,7 +823,7 @@ static int do_test_code_reading(bool try_kcore)
 
 	evlist__disable(evlist);
 
-	ret = process_events(machine, evlist, &state);
+	ret = process_events(machine, evlist, &tested_sections);
 	if (ret < 0)
 		goto out_put;
 
@@ -793,6 +843,7 @@ static int do_test_code_reading(bool try_kcore)
 	perf_thread_map__put(threads);
 	machine__delete(machine);
 	perf_env__exit(&host_env);
+	tested_sections__free(&tested_sections);
 
 	return err;
 }