[PATCH net-next] inet: reduce TLB pressure for listeners

[PATCH net-next] inet: reduce TLB pressure for listeners

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

It seems overkill to use vmalloc() for typical listeners with less than
2048 hash buckets. Try kmalloc() and fallback to vmalloc() to reduce TLB
pressure.

Use kvfree() helper as it is now available.
Use ilog2() instead of a loop.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 net/core/request_sock.c |   43 ++++++++++----------------------------
 1 file changed, 12 insertions(+), 31 deletions(-)

diff --git a/net/core/request_sock.c b/net/core/request_sock.c
index 467f326126e0..04db318e6218 100644
--- a/net/core/request_sock.c
+++ b/net/core/request_sock.c
@@ -41,27 +41,27 @@ int reqsk_queue_alloc(struct request_sock_queue *queue,
 		      unsigned int nr_table_entries)
 {
 	size_t lopt_size = sizeof(struct listen_sock);
-	struct listen_sock *lopt;
+	struct listen_sock *lopt = NULL;
 
 	nr_table_entries = min_t(u32, nr_table_entries, sysctl_max_syn_backlog);
 	nr_table_entries = max_t(u32, nr_table_entries, 8);
 	nr_table_entries = roundup_pow_of_two(nr_table_entries + 1);
 	lopt_size += nr_table_entries * sizeof(struct request_sock *);
-	if (lopt_size > PAGE_SIZE)
+
+	if (lopt_size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
+		lopt = kzalloc(lopt_size, GFP_KERNEL |
+					  __GFP_NOWARN |
+					  __GFP_NORETRY);
+	if (!lopt)
 		lopt = vzalloc(lopt_size);
-	else
-		lopt = kzalloc(lopt_size, GFP_KERNEL);
-	if (lopt == NULL)
+	if (!lopt)
 		return -ENOMEM;
 
-	for (lopt->max_qlen_log = 3;
-	     (1 << lopt->max_qlen_log) < nr_table_entries;
-	     lopt->max_qlen_log++);
-
 	get_random_bytes(&lopt->hash_rnd, sizeof(lopt->hash_rnd));
 	rwlock_init(&queue->syn_wait_lock);
 	queue->rskq_accept_head = NULL;
 	lopt->nr_table_entries = nr_table_entries;
+	lopt->max_qlen_log = ilog2(nr_table_entries);
 
 	write_lock_bh(&queue->syn_wait_lock);
 	queue->listen_opt = lopt;
@@ -72,22 +72,8 @@ int reqsk_queue_alloc(struct request_sock_queue *queue,
 
 void __reqsk_queue_destroy(struct request_sock_queue *queue)
 {
-	struct listen_sock *lopt;
-	size_t lopt_size;
-
-	/*
-	 * this is an error recovery path only
-	 * no locking needed and the lopt is not NULL
-	 */
-
-	lopt = queue->listen_opt;
-	lopt_size = sizeof(struct listen_sock) +
-		lopt->nr_table_entries * sizeof(struct request_sock *);
-
-	if (lopt_size > PAGE_SIZE)
-		vfree(lopt);
-	else
-		kfree(lopt);
+	/* This is an error recovery path only, no locking needed */
+	kvfree(queue->listen_opt);
 }
 
 static inline struct listen_sock *reqsk_queue_yank_listen_sk(
@@ -107,8 +93,6 @@ void reqsk_queue_destroy(struct request_sock_queue *queue)
 {
 	/* make all the listen_opt local to us */
 	struct listen_sock *lopt = reqsk_queue_yank_listen_sk(queue);
-	size_t lopt_size = sizeof(struct listen_sock) +
-		lopt->nr_table_entries * sizeof(struct request_sock *);
 
 	if (lopt->qlen != 0) {
 		unsigned int i;
@@ -125,10 +109,7 @@ void reqsk_queue_destroy(struct request_sock_queue *queue)
 	}
 
 	WARN_ON(lopt->qlen != 0);
-	if (lopt_size > PAGE_SIZE)
-		vfree(lopt);
-	else
-		kfree(lopt);
+	kvfree(lopt);
 }
 
 /*

Re: [PATCH net-next] inet: reduce TLB pressure for listeners

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 24 Jun 2014 05:32:48 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> It seems overkill to use vmalloc() for typical listeners with less than
> 2048 hash buckets. Try kmalloc() and fallback to vmalloc() to reduce TLB
> pressure.
> 
> Use kvfree() helper as it is now available.
> Use ilog2() instead of a loop.
> 
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied, thanks Eric.