Date: Mon, 10 Sep 2018 08:03:52 +0000 (UTC) From: Hans Petter Selasky <hselasky@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r338549 - stable/10/sys/dev/mlx5/mlx5_en Message-ID: <201809100803.w8A83rBp081769@repo.freebsd.org>
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Author: hselasky Date: Mon Sep 10 08:03:52 2018 New Revision: 338549 URL: https://svnweb.freebsd.org/changeset/base/338549 Log: MFC r338489: Maximum number of mbuf frags is off-by-one for worst case scenario in mlx5en(4). Inspecting the PRM no more than 0x3F data segments, DS, of size 16 bytes is allowed. Worst case scenario summary of DS usage: Header is fixed: 2 DS Maximum inlining: 98 => (98 - 2) / 16 = 6 DS Remainder: 0x3F - 2 - 6 = 55 DS (mbuf frags) Previously a value of 56 DS was used and this would work in the normal case because not all inline data area was used up. Sponsored by: Mellanox Technologies Modified: stable/10/sys/dev/mlx5/mlx5_en/en.h Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/dev/mlx5/mlx5_en/en.h ============================================================================== --- stable/10/sys/dev/mlx5/mlx5_en/en.h Mon Sep 10 08:02:02 2018 (r338548) +++ stable/10/sys/dev/mlx5/mlx5_en/en.h Mon Sep 10 08:03:52 2018 (r338549) @@ -125,7 +125,8 @@ #define MLX5E_MAX_TX_MBUF_SIZE 65536 /* bytes */ #define MLX5E_MAX_TX_MBUF_FRAGS \ ((MLX5_SEND_WQE_MAX_WQEBBS * MLX5_SEND_WQEBB_NUM_DS) - \ - (MLX5E_MAX_TX_HEADER / MLX5_SEND_WQE_DS)) /* units */ + (MLX5E_MAX_TX_HEADER / MLX5_SEND_WQE_DS) - \ + 1 /* the maximum value of the DS counter is 0x3F and not 0x40 */) /* units */ #define MLX5E_MAX_TX_INLINE \ (MLX5E_MAX_TX_HEADER - sizeof(struct mlx5e_tx_wqe) + \ sizeof(((struct mlx5e_tx_wqe *)0)->eth.inline_hdr_start)) /* bytes */
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