scanning: get async events from config setting

3 files changed, 22 insertions, 19 deletions

diff --git a/lib/device/dev-io.c b/lib/device/dev-io.c
index c8743f348..9bdc5e82c 100644
--- a/lib/device/dev-io.c
+++ b/lib/device/dev-io.c
@@ -835,20 +835,21 @@ int dev_set(struct device *dev, uint64_t offset, size_t len, int value)
 struct dev_async_context *dev_async_context_setup(unsigned async_event_count)
 {
 	struct dev_async_context *ac;
-	int max_submit_events = MAX_ASYNC_EVENTS;
+	unsigned nr_events = DEFAULT_ASYNC_EVENTS;
 	int error;
 
 	if (async_event_count)
-		max_submit_events = async_event_count;
+		nr_events = async_event_count;
 
 	if (!(ac = malloc(sizeof(struct dev_async_context))))
 		return_0;
 
 	memset(ac, 0, sizeof(struct dev_async_context));
 
-	error = io_setup(max_submit_events, &ac->aio_ctx);
+	error = io_setup(nr_events, &ac->aio_ctx);
 
 	if (error < 0) {
+		log_warn("WARNING: async io setup error %d with %u events.", error, nr_events);
 		free(ac);
 		return_0;
 	}
diff --git a/lib/device/device.h b/lib/device/device.h
index 87d19bd66..eb88fc83d 100644
--- a/lib/device/device.h
+++ b/lib/device/device.h
@@ -98,15 +98,6 @@ struct device_area {
  */
 #define MAX_GET_EVENTS 16
 
-/*
- * The number of events to use in io_setup(),
- * which is the limit on the number of concurrent
- * async i/o's we can submit.  After all these are
- * used, io_submit() returns -EAGAIN, and we revert
- * to doing synchronous io.
- */
-#define MAX_ASYNC_EVENTS 1024
-
 struct dev_async_context {
 	io_context_t aio_ctx;
 	struct io_event events[MAX_GET_EVENTS];
diff --git a/lib/label/label.c b/lib/label/label.c
index 99d2521a2..7d2ebfbff 100644
--- a/lib/label/label.c
+++ b/lib/label/label.c
@@ -732,23 +732,21 @@ static int _label_scan_async(struct cmd_context *cmd, int skip_cached)
 	int need_wait_count;
 	int need_process_count;
 	int dev_count = 0;
+	int async_event_count;
 
 	_free_label_read_list(0);
 
 	buf_len = _get_scan_size(cmd);
 
+	async_event_count = find_config_tree_int(cmd, devices_async_events_CFG, NULL);
+
 	/*
 	 * if aio setup fails, caller will revert to sync scan
 	 * The number of events set up here is the max number of
 	 * concurrent async reads that can be submitted.  After
 	 * all of those are used, we revert to synchronous reads.
-	 *
-	 * FIXME: add a config setting to control the number passed
-	 * into setup used for max async events in io_setup().
-	 * (0 uses default)
 	 */
-
-	if (!(ac = dev_async_context_setup(0))) {
+	if (!(ac = dev_async_context_setup(async_event_count))) {
 		log_debug_devs("async io setup error, reverting to sync io.");
 		return_0;
 	}
@@ -932,12 +930,25 @@ static int _label_scan_devs_async(struct cmd_context *cmd, struct dm_list *devs)
 	int need_wait_count;
 	int need_process_count;
 	int dev_count = 0;
+	int async_event_count;
+	int num_devs;
 
 	buf_len = _get_scan_size(cmd);
 
 	dm_list_init(&tmp_label_read_list);
 
-	if (!(ac = dev_async_context_setup(0))) {
+	async_event_count = find_config_tree_int(cmd, devices_async_events_CFG, NULL);
+	num_devs = dm_list_size(devs);
+
+	if (num_devs < async_event_count)
+		async_event_count = num_devs;
+
+	/*
+	 * Should we set up one global aio context when the command starts,
+	 * and then use/reuse that one context from multiple calls to
+	 * label_scan/label_scan_devs?
+	 */
+	if (!(ac = dev_async_context_setup(async_event_count))) {
 		log_debug_devs("async io setup error, reverting to sync io.");
 		return_0;
 	}