[PATCH v2 13/13] io_uring/rsrc: add custom limit for node caching

[Pavel Begunkov <asml.silence@gmail.com>]

The number of entries in the rsrc node cache is limited to 512, which
still seems unnecessarily large. Add per cache thresholds and set to
to 32 for the rsrc node cache.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 include/linux/io_uring_types.h | 1 +
 io_uring/alloc_cache.h         | 6 ++++--
 io_uring/io_uring.c            | 9 ++++++---
 io_uring/rsrc.h                | 2 ++
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 5d772e36e7fc..4a6ce03a4903 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -190,6 +190,7 @@ struct io_ev_fd {
 struct io_alloc_cache {
 	struct io_wq_work_node	list;
 	unsigned int		nr_cached;
+	unsigned int		max_cached;
 	size_t			elem_size;
 };
 
diff --git a/io_uring/alloc_cache.h b/io_uring/alloc_cache.h
index 2fbecaa3a1ba..851a527afb5e 100644
--- a/io_uring/alloc_cache.h
+++ b/io_uring/alloc_cache.h
@@ -13,7 +13,7 @@ struct io_cache_entry {
 static inline bool io_alloc_cache_put(struct io_alloc_cache *cache,
 				      struct io_cache_entry *entry)
 {
-	if (cache->nr_cached < IO_ALLOC_CACHE_MAX) {
+	if (cache->nr_cached < cache->max_cached) {
 		cache->nr_cached++;
 		wq_stack_add_head(&entry->node, &cache->list);
 		/* KASAN poisons object */
@@ -38,10 +38,12 @@ static inline struct io_cache_entry *io_alloc_cache_get(struct io_alloc_cache *c
 	return NULL;
 }
 
-static inline void io_alloc_cache_init(struct io_alloc_cache *cache, size_t size)
+static inline void io_alloc_cache_init(struct io_alloc_cache *cache,
+				       unsigned max_nr, size_t size)
 {
 	cache->list.next = NULL;
 	cache->nr_cached = 0;
+	cache->max_cached = max_nr;
 	cache->elem_size = size;
 }
 
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index da36fa1eeac9..ae90d2753e0d 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -310,9 +310,12 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	INIT_LIST_HEAD(&ctx->sqd_list);
 	INIT_LIST_HEAD(&ctx->cq_overflow_list);
 	INIT_LIST_HEAD(&ctx->io_buffers_cache);
-	io_alloc_cache_init(&ctx->rsrc_node_cache, sizeof(struct io_rsrc_node));
-	io_alloc_cache_init(&ctx->apoll_cache, sizeof(struct async_poll));
-	io_alloc_cache_init(&ctx->netmsg_cache, sizeof(struct io_async_msghdr));
+	io_alloc_cache_init(&ctx->rsrc_node_cache, IO_NODE_ALLOC_CACHE_MAX,
+			    sizeof(struct io_rsrc_node));
+	io_alloc_cache_init(&ctx->apoll_cache, IO_ALLOC_CACHE_MAX,
+			    sizeof(struct async_poll));
+	io_alloc_cache_init(&ctx->netmsg_cache, IO_ALLOC_CACHE_MAX,
+			    sizeof(struct io_async_msghdr));
 	init_completion(&ctx->ref_comp);
 	xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
 	mutex_init(&ctx->uring_lock);
diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 7ab9b2b2e757..8729f2fee256 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -6,6 +6,8 @@
 
 #include "alloc_cache.h"
 
+#define IO_NODE_ALLOC_CACHE_MAX 32
+
 #define IO_RSRC_TAG_TABLE_SHIFT	(PAGE_SHIFT - 3)
 #define IO_RSRC_TAG_TABLE_MAX	(1U << IO_RSRC_TAG_TABLE_SHIFT)
 #define IO_RSRC_TAG_TABLE_MASK	(IO_RSRC_TAG_TABLE_MAX - 1)
-- 
2.39.1