Commit 9731bc98 authored by Jens Axboe's avatar Jens Axboe
Browse files

io_uring: impose max limit on apoll cache 



Caches like this tend to grow to the peak size, and then never get any
smaller. Impose a max limit on the size, to prevent it from growing too
big.

A somewhat randomly chosen 512 is the max size we'll allow the cache
to get. If a batch of frees come in and would bring it over that, we
simply start kfree'ing the surplus.

Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 9b797a37

include/linux/io_uring_types.h

+1 −0
Original line number Diff line number Diff line
@@ -160,6 +160,7 @@ struct io_ev_fd { 


struct io_alloc_cache {

	struct hlist_head	list;

	unsigned int		nr_cached;

};



struct io_ring_ctx {

io_uring/alloc_cache.h

+14 −2
Original line number Diff line number Diff line 
#ifndef IOU_ALLOC_CACHE_H

#define IOU_ALLOC_CACHE_H



/*

 * Don't allow the cache to grow beyond this size.

 */

#define IO_ALLOC_CACHE_MAX	512



struct io_cache_entry {

	struct hlist_node	node;

};



static inline void io_alloc_cache_put(struct io_alloc_cache *cache,

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) {

		cache->nr_cached++;

		hlist_add_head(&entry->node, &cache->list);

		return true;

	}

	return false;

}



static inline struct io_cache_entry *io_alloc_cache_get(struct io_alloc_cache *cache)
@@ -26,6 +36,7 @@ static inline struct io_cache_entry *io_alloc_cache_get(struct io_alloc_cache *c 
static inline void io_alloc_cache_init(struct io_alloc_cache *cache)

{

	INIT_HLIST_HEAD(&cache->list);

	cache->nr_cached = 0;

}



static inline void io_alloc_cache_free(struct io_alloc_cache *cache,
@@ -37,5 +48,6 @@ static inline void io_alloc_cache_free(struct io_alloc_cache *cache, 
		hlist_del(node);

		free(container_of(node, struct io_cache_entry, node));

	}

	cache->nr_cached = 0;

}

#endif

io_uring/io_uring.c

+2 −1
Original line number Diff line number Diff line
@@ -1181,7 +1181,8 @@ void io_free_batch_list(struct io_ring_ctx *ctx, struct io_wq_work_node *node) 


				if (apoll->double_poll)

					kfree(apoll->double_poll);

				io_alloc_cache_put(&ctx->apoll_cache, &apoll->cache);

				if (!io_alloc_cache_put(&ctx->apoll_cache, &apoll->cache))

					kfree(apoll);

				req->flags &= ~REQ_F_POLLED;

			}

			if (req->flags & IO_REQ_LINK_FLAGS)