io_uring/poll: shrink alloc cache size to 32

This should be plenty, rather than the default of 128, and matches what
we have on the rsrc and futex side as well.

Signed-off-by: Jens Axboe <[email protected]>

Author: axboe

io_uring/io_uring.c

@@ -308,7 +308,7 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	INIT_HLIST_HEAD(&ctx->io_buf_list);
 	ret = io_alloc_cache_init(&ctx->rsrc_node_cache, IO_NODE_ALLOC_CACHE_MAX,
 			    sizeof(struct io_rsrc_node));
-	ret |= io_alloc_cache_init(&ctx->apoll_cache, IO_ALLOC_CACHE_MAX,
+	ret |= io_alloc_cache_init(&ctx->apoll_cache, IO_POLL_ALLOC_CACHE_MAX,
 			    sizeof(struct async_poll));
 	ret |= io_alloc_cache_init(&ctx->netmsg_cache, IO_ALLOC_CACHE_MAX,
 			    sizeof(struct io_async_msghdr));

io_uring/poll.h

@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
+#define IO_POLL_ALLOC_CACHE_MAX 32
+
 enum {
 	IO_APOLL_OK,
 	IO_APOLL_ABORTED,