| Message ID | 1575878189-31860-6-git-send-email-magnus.karlsson@intel.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | xsk: clean up ring access functions | expand |
Hello! On 09.12.2019 10:56, Magnus Karlsson wrote: > In the xsk consumer ring code there is a variable call RX_BATCH_SIZE Called? > 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 ^^^^^^^^^^^^^^^^^^^^^ hm, are you sure there's no typo here? > 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> [...] MBR, Sergei
On Mon, Dec 9, 2019 at 11:17 AM Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> wrote: > > Hello! > > On 09.12.2019 10:56, Magnus Karlsson wrote: > > > In the xsk consumer ring code there is a variable call RX_BATCH_SIZE > > Called? Yes, definitely. Will fix. Thanks: Magnus > > 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 > ^^^^^^^^^^^^^^^^^^^^^ hm, are you sure there's no typo here? > > > 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> > [...] > > MBR, Sergei >
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 */
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(-)