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From: Magnus Karlsson <magnus.karlsson@intel.com>
To: magnus.karlsson@intel.com, bjorn.topel@intel.com, ast@kernel.org,
	daniel@iogearbox.net, netdev@vger.kernel.org,
	jonathan.lemon@gmail.com
Cc: bpf@vger.kernel.org, saeedm@mellanox.com,
	jeffrey.t.kirsher@intel.com, maciej.fijalkowski@intel.com,
	maciejromanfijalkowski@gmail.com
Subject: [PATCH bpf-next 05/12] xsk: eliminate the RX batch size
Date: Mon,  9 Dec 2019 08:56:22 +0100	[thread overview]
Message-ID: <1575878189-31860-6-git-send-email-magnus.karlsson@intel.com> (raw)
In-Reply-To: <1575878189-31860-1-git-send-email-magnus.karlsson@intel.com>

In the xsk consumer ring code there is a variable call RX_BATCH_SIZE
that dictates the minimum number of entries that we try to grab from
the fill and Tx rings. In fact, the code always try to grab the
maximum amount of entries from these rings. The only thing this
variable does is to throw an error if there is less than 16 (as it is
defined) entries on the ring. There is no reason to do this and it
will just lead to weird behavior from user space's point of view. So
eliminate this variable.

With this change, we will be able to simplify the xskq_nb_free and
xskq_nb_avail code in the next commit.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
---
 net/xdp/xsk_queue.h | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 85358af..e3ae62d 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -10,8 +10,6 @@
 #include <linux/if_xdp.h>
 #include <net/xdp_sock.h>
 
-#define RX_BATCH_SIZE 16
-
 struct xdp_ring {
 	u32 producer ____cacheline_aligned_in_smp;
 	u32 consumer ____cacheline_aligned_in_smp;
@@ -202,7 +200,7 @@ static inline u64 *xskq_peek_addr(struct xsk_queue *q, u64 *addr,
 	if (q->cons_tail == q->cons_head) {
 		smp_mb(); /* D, matches A */
 		WRITE_ONCE(q->ring->consumer, q->cons_tail);
-		q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);
+		q->cons_head = q->cons_tail + xskq_nb_avail(q, 1);
 
 		/* Order consumer and data */
 		smp_rmb();
@@ -320,7 +318,7 @@ static inline struct xdp_desc *xskq_peek_desc(struct xsk_queue *q,
 	if (q->cons_tail == q->cons_head) {
 		smp_mb(); /* D, matches A */
 		WRITE_ONCE(q->ring->consumer, q->cons_tail);
-		q->cons_head = q->cons_tail + xskq_nb_avail(q, RX_BATCH_SIZE);
+		q->cons_head = q->cons_tail + xskq_nb_avail(q, 1);
 
 		/* Order consumer and data */
 		smp_rmb(); /* C, matches B */
-- 
2.7.4


  parent reply	other threads:[~2019-12-09  7:57 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09  7:56 [PATCH bpf-next 00/12] xsk: clean up ring access functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 01/12] xsk: eliminate the lazy update threshold Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 02/12] xsk: consolidate to one single cached producer pointer Magnus Karlsson
2019-12-10  0:42   ` Martin Lau
2019-12-10  9:04     ` Magnus Karlsson
2019-12-13 18:04   ` Maxim Mikityanskiy
2019-12-16  8:46     ` Magnus Karlsson
2019-12-19 14:35       ` Maxim Mikityanskiy
2019-12-19 16:21         ` Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 03/12] xsk: standardize naming of producer ring access functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 04/12] xsk: simplify detection of empty and full rings Magnus Karlsson
2019-12-09  7:56 ` Magnus Karlsson [this message]
2019-12-09 10:16   ` [PATCH bpf-next 05/12] xsk: eliminate the RX batch size Sergei Shtylyov
2019-12-09 13:07     ` Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 06/12] xsk: simplify xskq_nb_avail and xskq_nb_free Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 07/12] xsk: simplify the consumer ring access functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 08/12] xsk: change names of validation functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 09/12] xsk: ixgbe: i40e: ice: mlx5: xsk_umem_discard_addr to xsk_umem_release_addr Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 10/12] xsk: remove unnecessary READ_ONCE of data Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 11/12] xsk: add function naming comments and reorder functions Magnus Karlsson
2019-12-09  7:56 ` [PATCH bpf-next 12/12] xsk: use struct_size() helper Magnus Karlsson
2019-12-10  1:02 ` [PATCH bpf-next 00/12] xsk: clean up ring access functions Martin Lau

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