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[net-next,15/15] net/mlx5e: XDP, Exclude headroom and tailroom from memory calculations

Message ID 20240126223616.98696-16-saeed@kernel.org (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [net-next,01/15] xfrm: generalize xdo_dev_state_update_curlft to allow statistics update | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1064 this patch: 1064
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers success CCed 0 of 0 maintainers
netdev/build_clang success Errors and warnings before: 1081 this patch: 1081
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1081 this patch: 1081
netdev/checkpatch warning WARNING: line length of 100 exceeds 80 columns WARNING: line length of 87 exceeds 80 columns WARNING: line length of 97 exceeds 80 columns WARNING: line length of 99 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Saeed Mahameed Jan. 26, 2024, 10:36 p.m. UTC 
From: Carolina Jubran <cjubran@nvidia.com>

In the case of XDP Multi-Buffer with Striding RQ, an extra
page is allocated for the linear part of non-linear SKBs.

Including headroom and tailroom in the calculation may
result in an unnecessary increase in the amount of memory
allocated. This could be critical, particularly for large
MTUs (e.g. 7975B) and large RQ sizes (e.g. 8192).

In this case, the requested page pool size is 64K, but
32K would be sufficient. This causes a failure due to
exceeding the page pool size limit of 32K.

Exclude headroom and tailroom from SKB size calculations
to reduce page pool size.

Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/params.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
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Patch

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
index b9d39ef8053c..5757f4f10c12 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.c
@@ -257,6 +257,7 @@  static u32 mlx5e_rx_get_linear_stride_sz(struct mlx5_core_dev *mdev,
 					 struct mlx5e_xsk_param *xsk,
 					 bool mpwqe)
 {
+	bool no_head_tail_room;
 	u32 sz;
 
 	/* XSK frames are mapped as individual pages, because frames may come in
@@ -265,7 +266,13 @@  static u32 mlx5e_rx_get_linear_stride_sz(struct mlx5_core_dev *mdev,
 	if (xsk)
 		return mpwqe ? 1 << mlx5e_mpwrq_page_shift(mdev, xsk) : PAGE_SIZE;
 
-	sz = roundup_pow_of_two(mlx5e_rx_get_linear_sz_skb(params, false));
+	no_head_tail_room = params->xdp_prog && mpwqe && !mlx5e_rx_is_linear_skb(mdev, params, xsk);
+
+	/* When no_head_tail_room is set, headroom and tailroom are excluded from skb calculations.
+	 * no_head_tail_room should be set in the case of XDP with Striding RQ
+	 * when SKB is not linear. This is because another page is allocated for the linear part.
+	 */
+	sz = roundup_pow_of_two(mlx5e_rx_get_linear_sz_skb(params, no_head_tail_room));
 
 	/* XDP in mlx5e doesn't support multiple packets per page.
 	 * Do not assume sz <= PAGE_SIZE if params->xdp_prog is set.