bdev: add global structure for bdev_io options

Currently this just includes the overall size of the
spdk_bdev_io pool and the size of the per-thread
spdk_bdev_io caches.

Later patches will allow configuring these via
INI config file and JSON-RPC.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: I7e235ee6d2d7123d8460eeacde999c7b51017c43

Reviewed-on: https://review.gerrithub.io/414710
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

include/spdk/bdev.h

@@ -128,6 +128,15 @@ struct spdk_bdev_io_stat {
 	uint64_t ticks_rate;
 };
 
+struct spdk_bdev_opts {
+	uint32_t bdev_io_pool_size;
+	uint32_t bdev_io_cache_size;
+};
+
+void spdk_bdev_get_opts(struct spdk_bdev_opts *opts);
+
+int spdk_bdev_set_opts(struct spdk_bdev_opts *opts);
+
 /**
  * Block device initialization callback.
  *

lib/bdev/bdev.c

@@ -104,6 +104,11 @@ static struct spdk_bdev_mgr g_bdev_mgr = {
 	.module_init_complete = false,
 };
 
+static struct spdk_bdev_opts	g_bdev_opts = {
+	.bdev_io_pool_size = SPDK_BDEV_IO_POOL_SIZE,
+	.bdev_io_cache_size = SPDK_BDEV_IO_CACHE_SIZE,
+};
+
 static spdk_bdev_init_cb	g_init_cb_fn = NULL;
 static void			*g_init_cb_arg = NULL;
 
@@ -158,6 +163,7 @@ struct spdk_bdev_mgmt_channel {
 	 */
 	bdev_io_stailq_t per_thread_cache;
 	uint32_t	per_thread_cache_count;
+	uint32_t	bdev_io_cache_size;
 
 	TAILQ_HEAD(, spdk_bdev_shared_resource) shared_resources;
 };
@@ -249,6 +255,26 @@ struct spdk_bdev_iostat_ctx {
 
 static void spdk_bdev_write_zeroes_split(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg);
 
+void
+spdk_bdev_get_opts(struct spdk_bdev_opts *opts)
+{
+	*opts = g_bdev_opts;
+}
+
+int
+spdk_bdev_set_opts(struct spdk_bdev_opts *opts)
+{
+	if (opts->bdev_io_pool_size < opts->bdev_io_cache_size * spdk_thread_get_count()) {
+		SPDK_ERRLOG("bdev_io_pool_size %" PRIu32 " is not compatible with bdev_io_cache_size %" PRIu32
+			    " and %" PRIu32 " threads\n", opts->bdev_io_pool_size, opts->bdev_io_cache_size,
+			    spdk_thread_get_count());
+		return -1;
+	}
+
+	g_bdev_opts = *opts;
+	return 0;
+}
+
 struct spdk_bdev *
 spdk_bdev_first(void)
 {
@@ -483,6 +509,7 @@ spdk_bdev_mgmt_channel_create(void *io_device, void *ctx_buf)
 
 	STAILQ_INIT(&ch->per_thread_cache);
 	ch->per_thread_cache_count = 0;
+	ch->bdev_io_cache_size = g_bdev_opts.bdev_io_cache_size;
 
 	TAILQ_INIT(&ch->shared_resources);
 
@@ -606,6 +633,7 @@ spdk_bdev_modules_init(void)
 	g_bdev_mgr.module_init_complete = true;
 	return rc;
 }
+
 void
 spdk_bdev_initialize(spdk_bdev_init_cb cb_fn, void *cb_arg)
 {
@@ -621,7 +649,7 @@ spdk_bdev_initialize(spdk_bdev_init_cb cb_fn, void *cb_arg)
 	snprintf(mempool_name, sizeof(mempool_name), "bdev_io_%d", getpid());
 
 	g_bdev_mgr.bdev_io_pool = spdk_mempool_create(mempool_name,
-				  SPDK_BDEV_IO_POOL_SIZE,
+				  g_bdev_opts.bdev_io_pool_size,
 				  sizeof(struct spdk_bdev_io) +
 				  spdk_bdev_module_get_max_ctx_size(),
 				  0,
@@ -697,10 +725,10 @@ spdk_bdev_mgr_unregister_cb(void *io_device)
 {
 	spdk_bdev_fini_cb cb_fn = g_fini_cb_fn;
 
-	if (spdk_mempool_count(g_bdev_mgr.bdev_io_pool) != SPDK_BDEV_IO_POOL_SIZE) {
+	if (spdk_mempool_count(g_bdev_mgr.bdev_io_pool) != g_bdev_opts.bdev_io_pool_size) {
 		SPDK_ERRLOG("bdev IO pool count is %zu but should be %u\n",
 			    spdk_mempool_count(g_bdev_mgr.bdev_io_pool),
-			    SPDK_BDEV_IO_POOL_SIZE);
+			    g_bdev_opts.bdev_io_pool_size);
 	}
 
 	if (spdk_mempool_count(g_bdev_mgr.buf_small_pool) != BUF_SMALL_POOL_SIZE) {
@@ -862,7 +890,7 @@ spdk_bdev_put_io(struct spdk_bdev_io *bdev_io)
 		spdk_bdev_io_put_buf(bdev_io);
 	}
 
-	if (ch->per_thread_cache_count < SPDK_BDEV_IO_CACHE_SIZE) {
+	if (ch->per_thread_cache_count < ch->bdev_io_cache_size) {
 		ch->per_thread_cache_count++;
 		STAILQ_INSERT_TAIL(&ch->per_thread_cache, bdev_io, internal.buf_link);
 	} else {