[RFC PATCH 3/4] mlx5: use page_pool
From: Jesper Dangaard Brouer <hidden>
Date: 2016-12-20 13:28:26
Also in:
linux-mm
Subsystem:
mellanox ethernet driver (mlx5e), mellanox mlx5 core vpi driver, networking drivers, the rest · Maintainers:
Saeed Mahameed, Tariq Toukan, Mark Bloch, Leon Romanovsky, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The mlx5 driver already have a driver local page recycle cache. This
page cache is only efficient when the number of outstanding pages is
small, the queue based cache array size is 128. Further more a single
page with elevated refcnt can block the queue.
Benchmarking on next-next at commit f5f99309fa74 ("sock: do not set
sk_err in sock_dequeue_err_skb"), which include Paolo's UDP
performance optimizations (commit fc13fd398625 ("Merge branch
'udp-fwd-mem-sched-on-dequeue'"). Showed a speedup of 29% for UDP
packets. Detailed ethtool stats showed mlx5 page recycler didn't
"work" in that benchmark. The XDP_DROP use-case, showed a small perf
regression +2.7ns using page_pool. This correspons well to the 28%
gain reported in commit 1bfecfca565c ("net/mlx5e: Build RX SKB on
demand").
UPDATE: On newer kernels, net-next at commit 52f40e9d65. The mlx5 page
recycle cache works again, and performance gain is gone. Detailed
benchmarking show, RX-ksoftirq side is approx 10% faster, while UDP
socket delivery is same performance.
For TC early ingress drop there is a small performance regression of
approx +4 ns. There are pending page_pool optimization that will
close that gap.
Signed-off-by: Jesper Dangaard Brouer <redacted>
---
drivers/net/ethernet/mellanox/mlx5/core/en.h | 1
drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 28 +++++++++++++
drivers/net/ethernet/mellanox/mlx5/core/en_rx.c | 47 ++++++++++++++-------
3 files changed, 60 insertions(+), 16 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 951dbd58594d..b30d5b08d6a6 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h@@ -361,6 +361,7 @@ struct mlx5e_rq { struct mlx5e_tstamp *tstamp; struct mlx5e_rq_stats stats; struct mlx5e_cq cq; + struct page_pool *page_pool; struct mlx5e_page_cache page_cache; mlx5e_fp_handle_rx_cqe handle_rx_cqe;
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index cbfa38fc72c0..cd71e5764ec1 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c@@ -34,6 +34,7 @@ #include <net/pkt_cls.h> #include <linux/mlx5/fs.h> #include <net/vxlan.h> +#include <linux/page_pool.h> #include <linux/bpf.h> #include "en.h" #include "en_tc.h"
@@ -521,6 +522,7 @@ static int mlx5e_create_rq(struct mlx5e_channel *c, struct mlx5e_rq_param *param, struct mlx5e_rq *rq) { + struct page_pool_params pp_params = { 0 }; struct mlx5e_priv *priv = c->priv; struct mlx5_core_dev *mdev = priv->mdev; void *rqc = param->rqc;
@@ -591,6 +593,7 @@ static int mlx5e_create_rq(struct mlx5e_channel *c, default: /* MLX5_WQ_TYPE_LINKED_LIST */ rq->dma_info = kzalloc_node(wq_sz * sizeof(*rq->dma_info), GFP_KERNEL, cpu_to_node(c->cpu)); +// rq->dma_info = NULL; //HACK ALWAYS FAIL TEST if (!rq->dma_info) { err = -ENOMEM; goto err_rq_wq_destroy;
@@ -618,6 +621,24 @@ static int mlx5e_create_rq(struct mlx5e_channel *c, npages = DIV_ROUND_UP(frag_sz, PAGE_SIZE); rq->buff.page_order = order_base_2(npages); + pp_params.size = PAGE_POOL_PARAMS_SIZE; + pp_params.order = rq->buff.page_order; + pp_params.dev = c->pdev; + pp_params.nid = cpu_to_node(c->cpu); + pp_params.dma_dir = DMA_BIDIRECTIONAL; + pp_params.pool_size = 2000; + pr_info("XXX: %s() pp_params.size=%d end=%lu\n", + __func__, pp_params.size, + offsetof(struct page_pool_params, end_marker)); + + rq->page_pool = page_pool_create(&pp_params); + if (IS_ERR_OR_NULL(rq->page_pool)) { + rq->page_pool = NULL; + kfree(rq->dma_info); + err = -ENOMEM; + goto err_rq_wq_destroy; + } + byte_count |= MLX5_HW_START_PADDING; rq->mkey_be = c->mkey_be; }
@@ -662,6 +683,13 @@ static void mlx5e_destroy_rq(struct mlx5e_rq *rq) break; default: /* MLX5_WQ_TYPE_LINKED_LIST */ kfree(rq->dma_info); + if (rq->page_pool) + page_pool_destroy(rq->page_pool); + else + // Can happen because mlx5 have some extra + // rq's for some other purposes... (explain?) + pr_err("XXX: %s() NULL pointer at rq->page_pool\n", + __func__); } for (i = rq->page_cache.head; i != rq->page_cache.tail;
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 0e2fb3ed1790..0512632b30fd 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c@@ -182,6 +182,7 @@ void mlx5e_modify_rx_cqe_compression(struct mlx5e_priv *priv, bool val) #define RQ_PAGE_SIZE(rq) ((1 << rq->buff.page_order) << PAGE_SHIFT) +// TODO: Remove mlx5-page-cache static inline bool mlx5e_rx_cache_put(struct mlx5e_rq *rq, struct mlx5e_dma_info *dma_info) {
@@ -198,6 +199,7 @@ static inline bool mlx5e_rx_cache_put(struct mlx5e_rq *rq, return true; } +// TODO: Remove mlx5-page-cache static inline bool mlx5e_rx_cache_get(struct mlx5e_rq *rq, struct mlx5e_dma_info *dma_info) {
@@ -228,20 +230,27 @@ static inline int mlx5e_page_alloc_mapped(struct mlx5e_rq *rq, { struct page *page; - if (mlx5e_rx_cache_get(rq, dma_info)) - return 0; +// if (mlx5e_rx_cache_get(rq, dma_info)) +// return 0; - page = dev_alloc_pages(rq->buff.page_order); + //page = dev_alloc_pages(rq->buff.page_order); + page = page_pool_dev_alloc_pages(rq->page_pool); if (unlikely(!page)) return -ENOMEM; dma_info->page = page; - dma_info->addr = dma_map_page(rq->pdev, page, 0, - RQ_PAGE_SIZE(rq), rq->buff.map_dir); - if (unlikely(dma_mapping_error(rq->pdev, dma_info->addr))) { - put_page(page); - return -ENOMEM; - } + dma_info->addr = page->dma_addr; +// dma_info->addr = dma_map_page(rq->pdev, page, 0, +// RQ_PAGE_SIZE(rq), rq->buff.map_dir); + + /* DISCUSS: should this be moved into page_pool API? Here we + * sync entire page, but some drivers might want have more + * control? Like using the dma_sync_single_range_for_device() + * like Alex is doing in the Intel drivers... + */ + dma_sync_single_for_device(rq->pdev, dma_info->addr, + RQ_PAGE_SIZE(rq), + DMA_FROM_DEVICE); return 0; }
@@ -249,11 +258,21 @@ static inline int mlx5e_page_alloc_mapped(struct mlx5e_rq *rq, void mlx5e_page_release(struct mlx5e_rq *rq, struct mlx5e_dma_info *dma_info, bool recycle) { - if (likely(recycle) && mlx5e_rx_cache_put(rq, dma_info)) +// if (likely(recycle) && mlx5e_rx_cache_put(rq, dma_info)) +// return; + // TODO: use page_pool_recycle_direct(dma_info->page); + if (recycle) { + page_pool_recycle_direct(dma_info->page); return; + } + +// page_pool take over dma_unmap +// dma_unmap_page(rq->pdev, dma_info->addr, RQ_PAGE_SIZE(rq), +// rq->buff.map_dir); + // XXX: do we need to call dma_sync_single_range_for_cpu here??? + // dma_sync_single_range_for_cpu(rq->pdev, dma_info->addr, + // RQ_PAGE_SIZE(rq), rq->buff.map_dir); - dma_unmap_page(rq->pdev, dma_info->addr, RQ_PAGE_SIZE(rq), - rq->buff.map_dir); put_page(dma_info->page); }
@@ -773,10 +792,6 @@ struct sk_buff *skb_from_cqe(struct mlx5e_rq *rq, struct mlx5_cqe64 *cqe, return NULL; } - /* queue up for recycling ..*/ - page_ref_inc(di->page); - mlx5e_page_release(rq, di, true); - skb_reserve(skb, MLX5_RX_HEADROOM); skb_put(skb, cqe_bcnt); --
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