trace: allocate shm filesize based on number of cores used

Previously we would always allocate the shm file based on
max (128) cores which is unnecessary.  So use
spdk_env APIs to only allocate shm file size based
on the cores we might possible use.

With default settings, an shm file was 135MB before this
change, now an app using cores 0-7 will just use
about 9MB.

A lot of the trace-related code depended on there
*always* being a history for every core, even unused
ones, so a few additional changes were needed,
mainly the trace_parser library.

Tested by starting an app using a 0x4 core mask and
enabling a trace mask, generating some events, then
checking both the size of the shm file and that
spdk_trace works properly with the resulting file.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Ie868b3e3658d6f82b2fea37cb87453e8a9e0abc4
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/14044
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: Shuhei Matsumoto <smatsumoto@nvidia.com>

app/trace_record/trace_record.c

@@ -24,6 +24,7 @@ static uint64_t g_histories_size;
 struct lcore_trace_record_ctx {
 	char lcore_file[TRACE_PATH_MAX];
 	int fd;
+	bool valid;
 	struct spdk_trace_history *in_history;
 	struct spdk_trace_history *out_history;
 
@@ -94,11 +95,15 @@ input_trace_file_mmap(struct aggr_trace_record_ctx *ctx, const char *shm_name)
 
 	ctx->trace_histories = (struct spdk_trace_histories *)history_ptr;
 	for (i = 0; i < SPDK_TRACE_MAX_LCORE; i++) {
-		ctx->lcore_ports[i].in_history = spdk_get_per_lcore_history(ctx->trace_histories, i);
+		struct spdk_trace_history *history;
 
-		if (g_verbose) {
+		history = spdk_get_per_lcore_history(ctx->trace_histories, i);
+		ctx->lcore_ports[i].in_history = history;
+		ctx->lcore_ports[i].valid = (history != NULL);
+
+		if (g_verbose && history) {
 			printf("Number of trace entries for lcore (%d): %ju\n", i,
-			       ctx->lcore_ports[i].in_history->num_entries);
+			       history->num_entries);
 		}
 	}
 
@@ -149,6 +154,10 @@ output_trace_files_prepare(struct aggr_trace_record_ctx *ctx, const char *aggr_p
 	for (i = 0; i < SPDK_TRACE_MAX_LCORE; i++) {
 		port_ctx = &ctx->lcore_ports[i];
 
+		if (!port_ctx->valid) {
+			continue;
+		}
+
 		port_ctx->fd = open(port_ctx->lcore_file, flags, 0600);
 		if (port_ctx->fd < 0) {
 			fprintf(stderr, "Could not open lcore file %s.\n", port_ctx->lcore_file);
@@ -432,6 +441,7 @@ trace_files_aggregate(struct aggr_trace_record_ctx *ctx)
 	uint64_t lcore_offsets[SPDK_TRACE_MAX_LCORE + 1];
 	int rc, i;
 	ssize_t len = 0;
+	uint64_t current_offset;
 	uint64_t len_sum;
 
 	ctx->out_fd = open(ctx->out_file, flags, 0600);
@@ -453,11 +463,17 @@ trace_files_aggregate(struct aggr_trace_record_ctx *ctx)
 	}
 
 	/* Update and append lcore offsets converged trace file */
-	lcore_offsets[0] = sizeof(struct spdk_trace_flags);
-	for (i = 1; i < (int)SPDK_COUNTOF(lcore_offsets); i++) {
-		lcore_offsets[i] = spdk_get_trace_history_size(ctx->lcore_ports[i - 1].num_entries) +
-				   lcore_offsets[i - 1];
+	current_offset = sizeof(struct spdk_trace_flags);
+	for (i = 0; i < SPDK_TRACE_MAX_LCORE; i++) {
+		lcore_port = &ctx->lcore_ports[i];
+		if (lcore_port->valid) {
+			lcore_offsets[i] = current_offset;
+			current_offset += spdk_get_trace_history_size(lcore_port->num_entries);
+		} else {
+			lcore_offsets[i] = 0;
+		}
 	}
+	lcore_offsets[SPDK_TRACE_MAX_LCORE] = current_offset;
 
 	rc = cont_write(ctx->out_fd, lcore_offsets, sizeof(lcore_offsets));
 	if (rc < 0) {
@@ -469,6 +485,10 @@ trace_files_aggregate(struct aggr_trace_record_ctx *ctx)
 	for (i = 0; i < SPDK_TRACE_MAX_LCORE; i++) {
 		lcore_port = &ctx->lcore_ports[i];
 
+		if (!lcore_port->valid) {
+			continue;
+		}
+
 		lcore_port->out_history->num_entries = lcore_port->num_entries;
 		rc = cont_write(ctx->out_fd, lcore_port->out_history, sizeof(struct spdk_trace_history));
 		if (rc < 0) {
@@ -493,6 +513,9 @@ trace_files_aggregate(struct aggr_trace_record_ctx *ctx)
 			}
 		}
 
+		/* Clear rc so that the last cont_write() doesn't get interpreted as a failure. */
+		rc = 0;
+
 		if (len_sum != lcore_port->num_entries * sizeof(struct spdk_trace_entry)) {
 			fprintf(stderr, "Len of lcore trace file doesn't match number of entries for lcore\n");
 		}
@@ -639,6 +662,9 @@ main(int argc, char **argv)
 		for (i = 0; i < SPDK_TRACE_MAX_LCORE; i++) {
 			lcore_port = &ctx.lcore_ports[i];
 
+			if (!lcore_port->valid) {
+				continue;
+			}
 			rc = lcore_trace_record(lcore_port);
 			if (rc) {
 				break;

include/spdk/trace.h

@@ -157,16 +157,18 @@ spdk_get_trace_histories_size(struct spdk_trace_histories *trace_histories)
 static inline struct spdk_trace_history *
 spdk_get_per_lcore_history(struct spdk_trace_histories *trace_histories, unsigned lcore)
 {
-	char *lcore_history_offset;
+	uint64_t lcore_history_offset;
 
 	if (lcore >= SPDK_TRACE_MAX_LCORE) {
 		return NULL;
 	}
 
-	lcore_history_offset = (char *)trace_histories;
-	lcore_history_offset += trace_histories->flags.lcore_history_offsets[lcore];
+	lcore_history_offset = trace_histories->flags.lcore_history_offsets[lcore];
+	if (lcore_history_offset == 0) {
+		return NULL;
+	}
 
-	return (struct spdk_trace_history *)lcore_history_offset;
+	return (struct spdk_trace_history *)(((char *)trace_histories) + lcore_history_offset);
 }
 
 void _spdk_trace_record(uint64_t tsc, uint16_t tpoint_id, uint16_t poller_id,

lib/trace/trace.c

@@ -11,6 +11,7 @@
 #include "spdk/util.h"
 #include "spdk/barrier.h"
 #include "spdk/log.h"
+#include "spdk/cpuset.h"
 
 static int g_trace_fd = -1;
 static char g_shm_name[64];
@@ -142,20 +143,24 @@ _spdk_trace_record(uint64_t tsc, uint16_t tpoint_id, uint16_t poller_id, uint32_
 int
 spdk_trace_init(const char *shm_name, uint64_t num_entries)
 {
-	int i = 0;
+	uint32_t i = 0;
 	int histories_size;
-	uint64_t lcore_offsets[SPDK_TRACE_MAX_LCORE + 1];
+	uint64_t lcore_offsets[SPDK_TRACE_MAX_LCORE + 1] = { 0 };
+	struct spdk_cpuset cpuset = {};
 
 	/* 0 entries requested - skip trace initialization */
 	if (num_entries == 0) {
 		return 0;
 	}
 
-	lcore_offsets[0] = sizeof(struct spdk_trace_flags);
-	for (i = 1; i < (int)SPDK_COUNTOF(lcore_offsets); i++) {
-		lcore_offsets[i] = spdk_get_trace_history_size(num_entries) + lcore_offsets[i - 1];
+	spdk_cpuset_zero(&cpuset);
+	histories_size = sizeof(struct spdk_trace_flags);
+	SPDK_ENV_FOREACH_CORE(i) {
+		spdk_cpuset_set_cpu(&cpuset, i, true);
+		lcore_offsets[i] = histories_size;
+		histories_size += spdk_get_trace_history_size(num_entries);
 	}
-	histories_size = lcore_offsets[SPDK_TRACE_MAX_LCORE];
+	lcore_offsets[SPDK_TRACE_MAX_LCORE] = histories_size;
 
 	snprintf(g_shm_name, sizeof(g_shm_name), "%s", shm_name);
 
@@ -202,6 +207,10 @@ spdk_trace_init(const char *shm_name, uint64_t num_entries)
 		struct spdk_trace_history *lcore_history;
 
 		g_trace_flags->lcore_history_offsets[i] = lcore_offsets[i];
+		if (lcore_offsets[i] == 0) {
+			continue;
+		}
+		assert(spdk_cpuset_get_cpu(&cpuset, i));
 		lcore_history = spdk_get_per_lcore_history(g_trace_histories, i);
 		lcore_history->lcore = i;
 		lcore_history->num_entries = num_entries;
@@ -228,7 +237,7 @@ trace_init_err:
 void
 spdk_trace_cleanup(void)
 {
-	bool unlink;
+	bool unlink = true;
 	int i;
 	struct spdk_trace_history *lcore_history;
 
@@ -243,6 +252,9 @@ spdk_trace_cleanup(void)
 	 */
 	for (i = 0; i < SPDK_TRACE_MAX_LCORE; i++) {
 		lcore_history = spdk_get_per_lcore_history(g_trace_histories, i);
+		if (lcore_history == NULL) {
+			continue;
+		}
 		unlink = lcore_history->entries[0].tsc == 0;
 		if (!unlink) {
 			break;

lib/trace_parser/trace.cpp

@@ -97,9 +97,8 @@ spdk_trace_parser::entry_count(uint16_t lcore) const
 	}
 
 	history = spdk_get_per_lcore_history(_histories, lcore);
-	assert(history);
 
-	return history->num_entries;
+	return history == NULL ? 0 : history->num_entries;
 }
 
 spdk_trace_entry_buffer *
@@ -340,8 +339,7 @@ spdk_trace_parser::init(const spdk_trace_parser_opts *opts)
 	if (opts->lcore == SPDK_TRACE_MAX_LCORE) {
 		for (i = 0; i < SPDK_TRACE_MAX_LCORE; i++) {
 			history = spdk_get_per_lcore_history(_histories, i);
-			assert(history);
-			if (history->num_entries == 0 || history->entries[0].tsc == 0) {
+			if (history == NULL || history->num_entries == 0 || history->entries[0].tsc == 0) {
 				continue;
 			}
 
@@ -349,7 +347,11 @@ spdk_trace_parser::init(const spdk_trace_parser_opts *opts)
 		}
 	} else {
 		history = spdk_get_per_lcore_history(_histories, opts->lcore);
-		assert(history);
+		if (history == NULL) {
+			SPDK_ERRLOG("Trace file %s has no trace history for lcore %d\n",
+				    opts->filename, opts->lcore);
+			return false;
+		}
 		if (history->num_entries > 0 && history->entries[0].tsc != 0) {
 			populate_events(history, history->num_entries);
 		}

mk/spdk.unittest.mk

@@ -25,7 +25,7 @@ CFLAGS += -ffunction-sections
 CFLAGS += -DSPDK_UNIT_TEST=1
 LDFLAGS += -Wl,--gc-sections
 
-SPDK_LIB_LIST += thread util log trace
+SPDK_LIB_LIST += thread trace util log
 
 LIBS += -lcunit $(SPDK_STATIC_LIB_LINKER_ARGS)