diff mbox series

[RFC,Optimizing,veth,xsk,performance,02/10] xsk: add dma_check_skip for skipping dma check

Message ID 20230803140441.53596-3-huangjie.albert@bytedance.com
State New
Headers
Series |

Commit Message

黄杰 Aug. 3, 2023, 2:04 p.m. UTC 
  for the virtual net device such as veth, there is
no need to do dma check if we support zero copy.

add this flag after unaligned. beacause there are 4 bytes hole
pahole -V ./net/xdp/xsk_buff_pool.o:
-----------
...
	/* --- cacheline 3 boundary (192 bytes) --- */
	u32                        chunk_size;           /*   192     4 */
	u32                        frame_len;            /*   196     4 */
	u8                         cached_need_wakeup;   /*   200     1 */
	bool                       uses_need_wakeup;     /*   201     1 */
	bool                       dma_need_sync;        /*   202     1 */
	bool                       unaligned;            /*   203     1 */

	/* XXX 4 bytes hole, try to pack */

	void *                     addrs;                /*   208     8 */
	spinlock_t                 cq_lock;              /*   216     4 */
...
-----------

Signed-off-by: huangjie.albert <huangjie.albert@bytedance.com>
---
 include/net/xsk_buff_pool.h | 1 +
 net/xdp/xsk_buff_pool.c     | 3 ++-
 2 files changed, 3 insertions(+), 1 deletion(-)

Comments

Simon Horman Aug. 4, 2023, 8:42 p.m. UTC | #1 
On Thu, Aug 03, 2023 at 10:04:28PM +0800, huangjie.albert wrote:
> for the virtual net device such as veth, there is
> no need to do dma check if we support zero copy.
> 
> add this flag after unaligned. beacause there are 4 bytes hole

nit: beacause there are 4 bytes hole
  -> Because there is a 4 byte hole.
diff mbox series

Patch

diff --git a/include/net/xsk_buff_pool.h b/include/net/xsk_buff_pool.h
index b0bdff26fc88..fe31097dc11b 100644
--- a/include/net/xsk_buff_pool.h
+++ b/include/net/xsk_buff_pool.h
@@ -81,6 +81,7 @@  struct xsk_buff_pool {
 	bool uses_need_wakeup;
 	bool dma_need_sync;
 	bool unaligned;
+	bool dma_check_skip;
 	void *addrs;
 	/* Mutual exclusion of the completion ring in the SKB mode. Two cases to protect:
 	 * NAPI TX thread and sendmsg error paths in the SKB destructor callback and when
diff --git a/net/xdp/xsk_buff_pool.c b/net/xdp/xsk_buff_pool.c
index b3f7b310811e..ed251b8e8773 100644
--- a/net/xdp/xsk_buff_pool.c
+++ b/net/xdp/xsk_buff_pool.c
@@ -85,6 +85,7 @@  struct xsk_buff_pool *xp_create_and_assign_umem(struct xdp_sock *xs,
 		XDP_PACKET_HEADROOM;
 	pool->umem = umem;
 	pool->addrs = umem->addrs;
+	pool->dma_check_skip = false;
 	INIT_LIST_HEAD(&pool->free_list);
 	INIT_LIST_HEAD(&pool->xskb_list);
 	INIT_LIST_HEAD(&pool->xsk_tx_list);
@@ -202,7 +203,7 @@  int xp_assign_dev(struct xsk_buff_pool *pool,
 	if (err)
 		goto err_unreg_pool;
 
-	if (!pool->dma_pages) {
+	if (!pool->dma_pages && !pool->dma_check_skip) {
 		WARN(1, "Driver did not DMA map zero-copy buffers");
 		err = -EINVAL;
 		goto err_unreg_xsk;