From: Saeed Mahameed <saeed@kernel•org>
To: "David S. Miller" <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>, Paolo Abeni <pabeni@redhat•com>,
Eric Dumazet <edumazet@google•com>
Cc: Saeed Mahameed <saeedm@nvidia•com>,
netdev@vger•kernel.org, Tariq Toukan <tariqt@nvidia•com>,
Maxim Mikityanskiy <maximmi@nvidia•com>
Subject: [PATCH net-next 04/16] net/mlx5e: Make the wqe_index_mask calculation more exact
Date: Fri, 30 Sep 2022 09:28:51 -0700 [thread overview]
Message-ID: <20220930162903.62262-5-saeed@kernel.org> (raw)
In-Reply-To: <20220930162903.62262-1-saeed@kernel.org>
From: Maxim Mikityanskiy <maximmi@nvidia•com>
The old calculation of wqe_index_mask may give false positives, i.e.
request bulking of pairs of WQEs when not strictly needed, for example,
when the first fragment size is equal to the PAGE_SIZE, bulking is not
needed, even if the number of fragments is odd.
Make the calculation more exact to cut false positives.
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia•com>
Reviewed-by: Tariq Toukan <tariqt@nvidia•com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia•com>
---
.../ethernet/mellanox/mlx5/core/en/params.c | 21 ++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
index 49306a68b3b5..ac4d70bb21e8 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
@@ -648,7 +648,26 @@ static int mlx5e_build_rq_frags_info(struct mlx5_core_dev *mdev,
* is not completed yet, WQE 2*N must not be allocated, as it's
* responsible for allocating a new page.
*/
- info->wqe_index_mask = info->num_frags % 2;
+ if (frag_size_max == PAGE_SIZE) {
+ /* No WQE can start in the middle of a page. */
+ info->wqe_index_mask = 0;
+ } else {
+ /* PAGE_SIZEs starting from 8192 don't use 2K-sized fragments,
+ * because there would be more than MLX5E_MAX_RX_FRAGS of them.
+ */
+ WARN_ON(PAGE_SIZE != 2 * DEFAULT_FRAG_SIZE);
+
+ /* Odd number of fragments allows to pack the last fragment of
+ * the previous WQE and the first fragment of the next WQE into
+ * the same page.
+ * As long as DEFAULT_FRAG_SIZE is 2048, and MLX5E_MAX_RX_FRAGS
+ * is 4, the last fragment can be bigger than the rest only if
+ * it's the fourth one, so WQEs consisting of 3 fragments will
+ * always share a page.
+ * When a page is shared, WQE bulk size is 2, otherwise just 1.
+ */
+ info->wqe_index_mask = info->num_frags % 2;
+ }
out:
/* Bulking optimization to skip allocation until at least 8 WQEs can be
--
2.37.3
next prev parent reply other threads:[~2022-09-30 16:29 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-30 16:28 [PATCH net-next 00/16] mlx5 xsk updates part3 2022-09-30 Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 01/16] net/mlx5e: xsk: Use mlx5e_trigger_napi_icosq for XSK wakeup Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 02/16] net/mlx5e: xsk: Drop the check for XSK state in mlx5e_xsk_wakeup Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 03/16] net/mlx5e: Introduce wqe_index_mask for legacy RQ Saeed Mahameed
2022-09-30 16:28 ` Saeed Mahameed [this message]
2022-09-30 16:28 ` [PATCH net-next 05/16] net/mlx5e: Use partial batches in " Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 06/16] net/mlx5e: xsk: Use partial batches in legacy RQ with XSK Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 07/16] net/mlx5e: Remove the outer loop when allocating legacy RQ WQEs Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 08/16] net/mlx5e: xsk: Split out WQE allocation for legacy XSK RQ Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 09/16] net/mlx5e: xsk: Use xsk_buff_alloc_batch on legacy RQ Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 10/16] net/mlx5e: xsk: Use xsk_buff_alloc_batch on striding RQ Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 11/16] net/mlx5e: Use non-XSK page allocator in SHAMPO Saeed Mahameed
2022-09-30 16:28 ` [PATCH net-next 12/16] net/mlx5e: Call mlx5e_page_release_dynamic directly where possible Saeed Mahameed
2022-09-30 16:29 ` [PATCH net-next 13/16] net/mlx5e: Optimize RQ page deallocation Saeed Mahameed
2022-09-30 16:29 ` [PATCH net-next 14/16] net/mlx5e: xsk: Support XDP metadata on XSK RQs Saeed Mahameed
2022-09-30 16:29 ` [PATCH net-next 15/16] net/mlx5e: Introduce the mlx5e_flush_rq function Saeed Mahameed
2022-09-30 16:29 ` [PATCH net-next 16/16] net/mlx5e: xsk: Use queue indices starting from 0 for XSK queues Saeed Mahameed
2022-10-01 20:40 ` [PATCH net-next 00/16] mlx5 xsk updates part3 2022-09-30 patchwork-bot+netdevbpf
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