bootstage: Use rec_count as the array index

At present bootstage has a large array with all possible bootstage IDs
recorded. It adds times to the array element indexed by the ID. This is
inefficient because many IDs are not used during boot. We can save space
by only recording those IDs which actually have timestamps.

Update the array to use a record count, which increments with each
addition of a new timestamp. This takes longer to record a time, since it
may involve an array search. Such a search may be particularly expensive
before relocation when the CPU is running slowly or the cache is off. But
at that stage there should be very few records.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/Kconfig

@@ -46,6 +46,13 @@ config BOOTSTAGE_USER_COUNT
 	  a new ID will be allocated from this stash. If you exceed
 	  the limit, recording will stop.
 
+config BOOTSTAGE_RECORD_COUNT
+	int "Number of boot stage records to store"
+	default 30
+	help
+	  This is the size of the bootstage record list and is the maximum
+	  number of bootstage records that can be recorded.
+
 config BOOTSTAGE_FDT
 	bool "Store boot timing information in the OS device tree"
 	depends on BOOTSTAGE

common/bootstage.c

@@ -17,6 +17,10 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+enum {
+	RECORD_COUNT = CONFIG_BOOTSTAGE_RECORD_COUNT,
+};
+
 struct bootstage_record {
 	ulong time_us;
 	uint32_t start_us;
@@ -26,8 +30,9 @@ struct bootstage_record {
 };
 
 struct bootstage_data {
+	uint rec_count;
 	uint next_id;
-	struct bootstage_record record[BOOTSTAGE_ID_COUNT];
+	struct bootstage_record record[RECORD_COUNT];
 };
 
 enum {
@@ -52,13 +57,43 @@ int bootstage_relocate(void)
 	 * Duplicate all strings.  They may point to an old location in the
 	 * program .text section that can eventually get trashed.
 	 */
-	for (i = 0; i < BOOTSTAGE_ID_COUNT; i++)
-		if (data->record[i].name)
-			data->record[i].name = strdup(data->record[i].name);
+	debug("Relocating %d records\n", data->rec_count);
+	for (i = 0; i < data->rec_count; i++)
+		data->record[i].name = strdup(data->record[i].name);
 
 	return 0;
 }
 
+struct bootstage_record *find_id(struct bootstage_data *data,
+				 enum bootstage_id id)
+{
+	struct bootstage_record *rec;
+	struct bootstage_record *end;
+
+	for (rec = data->record, end = rec + data->rec_count; rec < end;
+	     rec++) {
+		if (rec->id == id)
+			return rec;
+	}
+
+	return NULL;
+}
+
+struct bootstage_record *ensure_id(struct bootstage_data *data,
+				   enum bootstage_id id)
+{
+	struct bootstage_record *rec;
+
+	rec = find_id(data, id);
+	if (!rec && data->rec_count < RECORD_COUNT) {
+		rec = &data->record[data->rec_count++];
+		rec->id = id;
+		return rec;
+	}
+
+	return rec;
+}
+
 ulong bootstage_add_record(enum bootstage_id id, const char *name,
 			   int flags, ulong mark)
 {
@@ -68,16 +103,14 @@ ulong bootstage_add_record(enum bootstage_id id, const char *name,
 	if (flags & BOOTSTAGEF_ALLOC)
 		id = data->next_id++;
 
-	if (id < BOOTSTAGE_ID_COUNT) {
-		rec = &data->record[id];
-
-		/* Only record the first event for each */
-		if (!rec->time_us) {
-			rec->time_us = mark;
-			rec->name = name;
-			rec->flags = flags;
-			rec->id = id;
-		}
+	/* Only record the first event for each */
+	rec = find_id(data, id);
+	if (!rec && data->rec_count < RECORD_COUNT) {
+		rec = &data->record[data->rec_count++];
+		rec->time_us = mark;
+		rec->name = name;
+		rec->flags = flags;
+		rec->id = id;
 	}
 
 	/* Tell the board about this progress */
@@ -138,20 +171,25 @@ ulong bootstage_mark_code(const char *file, const char *func, int linenum)
 uint32_t bootstage_start(enum bootstage_id id, const char *name)
 {
 	struct bootstage_data *data = gd->bootstage;
-	struct bootstage_record *rec = &data->record[id];
+	struct bootstage_record *rec = ensure_id(data, id);
+	ulong start_us = timer_get_boot_us();
 
-	rec->start_us = timer_get_boot_us();
-	rec->name = name;
+	if (rec) {
+		rec->start_us = start_us;
+		rec->name = name;
+	}
 
-	return rec->start_us;
+	return start_us;
 }
 
 uint32_t bootstage_accum(enum bootstage_id id)
 {
 	struct bootstage_data *data = gd->bootstage;
-	struct bootstage_record *rec = &data->record[id];
+	struct bootstage_record *rec = ensure_id(data, id);
 	uint32_t duration;
 
+	if (!rec)
+		return 0;
 	duration = (uint32_t)timer_get_boot_us() - rec->start_us;
 	rec->time_us += duration;
 
@@ -214,7 +252,7 @@ static int add_bootstages_devicetree(struct fdt_header *blob)
 	struct bootstage_data *data = gd->bootstage;
 	int bootstage;
 	char buf[20];
-	int id;
+	int recnum;
 	int i;
 
 	if (!blob)
@@ -232,11 +270,11 @@ static int add_bootstages_devicetree(struct fdt_header *blob)
 	 * Insert the timings to the device tree in the reverse order so
 	 * that they can be printed in the Linux kernel in the right order.
 	 */
-	for (id = BOOTSTAGE_ID_COUNT - 1, i = 0; id >= 0; id--, i++) {
-		struct bootstage_record *rec = &data->record[id];
+	for (recnum = data->rec_count - 1, i = 0; recnum >= 0; recnum--, i++) {
+		struct bootstage_record *rec = &data->record[recnum];
 		int node;
 
-		if (id != BOOTSTAGE_ID_AWAKE && rec->time_us == 0)
+		if (rec->id != BOOTSTAGE_ID_AWAKE && rec->time_us == 0)
 			continue;
 
 		node = fdt_add_subnode(blob, bootstage, simple_itoa(i));
@@ -245,7 +283,7 @@ static int add_bootstages_devicetree(struct fdt_header *blob)
 
 		/* add properties to the node. */
 		if (fdt_setprop_string(blob, node, "name",
-				get_record_name(buf, sizeof(buf), rec)))
+				       get_record_name(buf, sizeof(buf), rec)))
 			return -1;
 
 		/* Check if this is a 'mark' or 'accum' record */
@@ -271,29 +309,29 @@ void bootstage_report(void)
 {
 	struct bootstage_data *data = gd->bootstage;
 	struct bootstage_record *rec = data->record;
-	int id;
 	uint32_t prev;
+	int i;
 
-	puts("Timer summary in microseconds:\n");
+	printf("Timer summary in microseconds (%d records):\n",
+	       data->rec_count);
 	printf("%11s%11s  %s\n", "Mark", "Elapsed", "Stage");
 
 	prev = print_time_record(rec, 0);
 
 	/* Sort records by increasing time */
-	qsort(data->record, ARRAY_SIZE(data->record), sizeof(*rec),
-	      h_compare_record);
+	qsort(data->record, data->rec_count, sizeof(*rec), h_compare_record);
 
-	for (id = 0; id < BOOTSTAGE_ID_COUNT; id++, rec++) {
-		if (rec->time_us != 0 && !rec->start_us)
+	for (i = 1, rec++; i < data->rec_count; i++, rec++) {
+		if (rec->id && !rec->start_us)
 			prev = print_time_record(rec, prev);
 	}
-	if (data->next_id > BOOTSTAGE_ID_COUNT)
-		printf("(Overflowed internal boot id table by %d entries\n"
-			"- please increase CONFIG_BOOTSTAGE_USER_COUNT\n",
-		       data->next_id - BOOTSTAGE_ID_COUNT);
+	if (data->rec_count > RECORD_COUNT)
+		printf("Overflowed internal boot id table by %d entries\n"
+		       "- please increase CONFIG_BOOTSTAGE_RECORD_COUNT\n",
+		       data->rec_count - RECORD_COUNT);
 
 	puts("\nAccumulated time:\n");
-	for (id = 0, rec = data->record; id < BOOTSTAGE_ID_COUNT; id++, rec++) {
+	for (i = 0, rec = data->record; i < data->rec_count; i++, rec++) {
 		if (rec->start_us)
 			prev = print_time_record(rec, -1);
 	}
@@ -329,7 +367,7 @@ int bootstage_stash(void *base, int size)
 	char buf[20];
 	char *ptr = base, *end = ptr + size;
 	uint32_t count;
-	int id;
+	int i;
 
 	if (hdr + 1 > (struct bootstage_hdr *)end) {
 		debug("%s: Not enough space for bootstage hdr\n", __func__);
@@ -340,9 +378,9 @@ int bootstage_stash(void *base, int size)
 	hdr->version = BOOTSTAGE_VERSION;
 
 	/* Count the number of records, and write that value first */
-	for (rec = data->record, id = count = 0; id < BOOTSTAGE_ID_COUNT;
-			id++, rec++) {
-		if (rec->time_us != 0)
+	for (rec = data->record, i = count = 0; i < data->rec_count;
+	     i++, rec++) {
+		if (rec->id != 0)
 			count++;
 	}
 	hdr->count = count;
@@ -351,13 +389,13 @@ int bootstage_stash(void *base, int size)
 	ptr += sizeof(*hdr);
 
 	/* Write the records, silently stopping when we run out of space */
-	for (rec = data->record, id = 0; id < BOOTSTAGE_ID_COUNT; id++, rec++) {
+	for (rec = data->record, i = 0; i < data->rec_count; i++, rec++) {
 		if (rec->time_us != 0)
 			append_data(&ptr, end, rec, sizeof(*rec));
 	}
 
 	/* Write the name strings */
-	for (rec = data->record, id = 0; id < BOOTSTAGE_ID_COUNT; id++, rec++) {
+	for (rec = data->record, i = 0; i < data->rec_count; i++, rec++) {
 		if (rec->time_us != 0) {
 			const char *name;
 
@@ -386,7 +424,7 @@ int bootstage_unstash(void *base, int size)
 	struct bootstage_record *rec;
 	char *ptr = base, *end = ptr + size;
 	uint rec_size;
-	int id;
+	int i;
 
 	if (size == -1)
 		end = (char *)(~(uintptr_t)0);
@@ -419,10 +457,10 @@ int bootstage_unstash(void *base, int size)
 		return -1;
 	}
 
-	if (data->next_id + hdr->count > BOOTSTAGE_ID_COUNT) {
+	if (data->rec_count + hdr->count > RECORD_COUNT) {
 		debug("%s: Bootstage has %d records, we have space for %d\n"
 			"- please increase CONFIG_BOOTSTAGE_USER_COUNT\n",
-		      __func__, hdr->count, BOOTSTAGE_ID_COUNT - data->next_id);
+		      __func__, hdr->count, RECORD_COUNT - data->rec_count);
 		return -1;
 	}
 
@@ -430,12 +468,12 @@ int bootstage_unstash(void *base, int size)
 
 	/* Read the records */
 	rec_size = hdr->count * sizeof(*data->record);
-	memcpy(data->record + data->next_id, ptr, rec_size);
+	memcpy(data->record + data->rec_count, ptr, rec_size);
 
 	/* Read the name strings */
 	ptr += rec_size;
-	for (rec = data->record + data->next_id, id = 0; id < hdr->count;
-	     id++, rec++) {
+	for (rec = data->record + data->next_id, i = 0; i < hdr->count;
+	     i++, rec++) {
 		rec->name = ptr;
 
 		/* Assume no data corruption here */
@@ -443,7 +481,7 @@ int bootstage_unstash(void *base, int size)
 	}
 
 	/* Mark the records as read */
-	data->next_id += hdr->count;
+	data->rec_count += hdr->count;
 	printf("Unstashed %d records\n", hdr->count);
 
 	return 0;
@@ -459,8 +497,10 @@ int bootstage_init(bool first)
 		return -ENOMEM;
 	data = gd->bootstage;
 	memset(data, '\0', size);
-	if (first)
+	if (first) {
+		data->next_id = BOOTSTAGE_ID_USER;
 		bootstage_add_record(BOOTSTAGE_ID_AWAKE, "reset", 0, 0);
+	}
 
 	return 0;
 }