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Date: Sun, 23 Jun 2013 08:17:56 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: Amir Vadai <amirv@...lanox.com>
Cc: "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
Or Gerlitz <ogerlitz@...lanox.com>,
Yevgeny Petrilin <yevgenyp@...lanox.com>
Subject: [PATCH net-next] mlx4: allow order-0 memory allocations in RX path
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
mlx4 exclusively uses order-2 allocations in RX path, which are
likely to fail under memory pressure.
We therefore drop frames more than needed.
This patch tries order-3, order-2, order-1 and finally order-0
allocations to keep good performance, yet allow allocations if/when
memory gets fragmented.
By using larger pages, and avoiding unnecessary get_page()/put_page()
on compound pages, this patch improves performance as well, lowering
false sharing on struct page.
Also use GFP_KERNEL allocations in initialization path, as allocating 12
MB (390 order-3 pages) can easily fail with GFP_ATOMIC.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Amir Vadai <amirv@...lanox.com>
---
drivers/net/ethernet/mellanox/mlx4/en_rx.c | 169 ++++++++---------
drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 12 -
2 files changed, 95 insertions(+), 86 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 9c57581..76997b9 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -43,40 +43,64 @@
#include "mlx4_en.h"
+static int mlx4_alloc_pages(struct mlx4_en_priv *priv,
+ struct mlx4_en_rx_alloc *page_alloc,
+ const struct mlx4_en_frag_info *frag_info,
+ gfp_t _gfp)
+{
+ int order;
+ struct page *page;
+ dma_addr_t dma;
+
+ for (order = MLX4_EN_ALLOC_PREFER_ORDER; ;) {
+ gfp_t gfp = _gfp;
+
+ if (order)
+ gfp |= __GFP_COMP | __GFP_NOWARN;
+ page = alloc_pages(gfp, order);
+ if (likely(page))
+ break;
+ if (--order < 0 ||
+ ((PAGE_SIZE << order) < frag_info->frag_size))
+ return -ENOMEM;
+ }
+ dma = dma_map_page(priv->ddev, page, 0, PAGE_SIZE << order,
+ PCI_DMA_FROMDEVICE);
+ if (dma_mapping_error(priv->ddev, dma)) {
+ put_page(page);
+ return -ENOMEM;
+ }
+ page_alloc->size = PAGE_SIZE << order;
+ page_alloc->page = page;
+ page_alloc->dma = dma;
+ page_alloc->offset = frag_info->frag_align;
+ /* Not doing get_page() for each frag is a big win
+ * on asymetric workloads.
+ */
+ atomic_set(&page->_count, page_alloc->size / frag_info->frag_stride);
+ return 0;
+}
+
static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
struct mlx4_en_rx_desc *rx_desc,
struct mlx4_en_rx_alloc *frags,
- struct mlx4_en_rx_alloc *ring_alloc)
+ struct mlx4_en_rx_alloc *ring_alloc,
+ gfp_t gfp)
{
struct mlx4_en_rx_alloc page_alloc[MLX4_EN_MAX_RX_FRAGS];
- struct mlx4_en_frag_info *frag_info;
+ const struct mlx4_en_frag_info *frag_info;
struct page *page;
dma_addr_t dma;
int i;
for (i = 0; i < priv->num_frags; i++) {
frag_info = &priv->frag_info[i];
- if (ring_alloc[i].offset == frag_info->last_offset) {
- page = alloc_pages(GFP_ATOMIC | __GFP_COMP,
- MLX4_EN_ALLOC_ORDER);
- if (!page)
- goto out;
- dma = dma_map_page(priv->ddev, page, 0,
- MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE);
- if (dma_mapping_error(priv->ddev, dma)) {
- put_page(page);
- goto out;
- }
- page_alloc[i].page = page;
- page_alloc[i].dma = dma;
- page_alloc[i].offset = frag_info->frag_align;
- } else {
- page_alloc[i].page = ring_alloc[i].page;
- get_page(ring_alloc[i].page);
- page_alloc[i].dma = ring_alloc[i].dma;
- page_alloc[i].offset = ring_alloc[i].offset +
- frag_info->frag_stride;
- }
+ page_alloc[i] = ring_alloc[i];
+ page_alloc[i].offset += frag_info->frag_stride;
+ if (page_alloc[i].offset + frag_info->frag_stride <= ring_alloc[i].size)
+ continue;
+ if (mlx4_alloc_pages(priv, &page_alloc[i], frag_info, gfp))
+ goto out;
}
for (i = 0; i < priv->num_frags; i++) {
@@ -88,14 +112,16 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
return 0;
-
out:
while (i--) {
frag_info = &priv->frag_info[i];
- if (ring_alloc[i].offset == frag_info->last_offset)
+ if (page_alloc[i].page != ring_alloc[i].page) {
dma_unmap_page(priv->ddev, page_alloc[i].dma,
- MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE);
- put_page(page_alloc[i].page);
+ page_alloc[i].size, PCI_DMA_FROMDEVICE);
+ page = page_alloc[i].page;
+ atomic_set(&page->_count, 1);
+ put_page(page);
+ }
}
return -ENOMEM;
}
@@ -104,12 +130,12 @@ static void mlx4_en_free_frag(struct mlx4_en_priv *priv,
struct mlx4_en_rx_alloc *frags,
int i)
{
- struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
+ const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
- if (frags[i].offset == frag_info->last_offset) {
- dma_unmap_page(priv->ddev, frags[i].dma, MLX4_EN_ALLOC_SIZE,
+ if (frags[i].offset + frag_info->frag_stride > frags[i].size)
+ dma_unmap_page(priv->ddev, frags[i].dma, frags[i].size,
PCI_DMA_FROMDEVICE);
- }
+
if (frags[i].page)
put_page(frags[i].page);
}
@@ -117,35 +143,28 @@ static void mlx4_en_free_frag(struct mlx4_en_priv *priv,
static int mlx4_en_init_allocator(struct mlx4_en_priv *priv,
struct mlx4_en_rx_ring *ring)
{
- struct mlx4_en_rx_alloc *page_alloc;
int i;
+ struct mlx4_en_rx_alloc *page_alloc;
for (i = 0; i < priv->num_frags; i++) {
- page_alloc = &ring->page_alloc[i];
- page_alloc->page = alloc_pages(GFP_ATOMIC | __GFP_COMP,
- MLX4_EN_ALLOC_ORDER);
- if (!page_alloc->page)
- goto out;
+ const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
- page_alloc->dma = dma_map_page(priv->ddev, page_alloc->page, 0,
- MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE);
- if (dma_mapping_error(priv->ddev, page_alloc->dma)) {
- put_page(page_alloc->page);
- page_alloc->page = NULL;
+ if (mlx4_alloc_pages(priv, &ring->page_alloc[i],
+ frag_info, GFP_KERNEL))
goto out;
- }
- page_alloc->offset = priv->frag_info[i].frag_align;
- en_dbg(DRV, priv, "Initialized allocator:%d with page:%p\n",
- i, page_alloc->page);
}
return 0;
out:
while (i--) {
+ struct page *page;
+
page_alloc = &ring->page_alloc[i];
dma_unmap_page(priv->ddev, page_alloc->dma,
- MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE);
- put_page(page_alloc->page);
+ page_alloc->size, PCI_DMA_FROMDEVICE);
+ page = page_alloc->page;
+ atomic_set(&page->_count, 1);
+ put_page(page);
page_alloc->page = NULL;
}
return -ENOMEM;
@@ -158,13 +177,18 @@ static void mlx4_en_destroy_allocator(struct mlx4_en_priv *priv,
int i;
for (i = 0; i < priv->num_frags; i++) {
+ const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
+
page_alloc = &ring->page_alloc[i];
en_dbg(DRV, priv, "Freeing allocator:%d count:%d\n",
i, page_count(page_alloc->page));
dma_unmap_page(priv->ddev, page_alloc->dma,
- MLX4_EN_ALLOC_SIZE, PCI_DMA_FROMDEVICE);
- put_page(page_alloc->page);
+ page_alloc->size, PCI_DMA_FROMDEVICE);
+ while (page_alloc->offset + frag_info->frag_stride < page_alloc->size) {
+ put_page(page_alloc->page);
+ page_alloc->offset += frag_info->frag_stride;
+ }
page_alloc->page = NULL;
}
}
@@ -195,13 +219,14 @@ static void mlx4_en_init_rx_desc(struct mlx4_en_priv *priv,
}
static int mlx4_en_prepare_rx_desc(struct mlx4_en_priv *priv,
- struct mlx4_en_rx_ring *ring, int index)
+ struct mlx4_en_rx_ring *ring, int index,
+ gfp_t gfp)
{
struct mlx4_en_rx_desc *rx_desc = ring->buf + (index * ring->stride);
struct mlx4_en_rx_alloc *frags = ring->rx_info +
(index << priv->log_rx_info);
- return mlx4_en_alloc_frags(priv, rx_desc, frags, ring->page_alloc);
+ return mlx4_en_alloc_frags(priv, rx_desc, frags, ring->page_alloc, gfp);
}
static inline void mlx4_en_update_rx_prod_db(struct mlx4_en_rx_ring *ring)
@@ -235,7 +260,8 @@ static int mlx4_en_fill_rx_buffers(struct mlx4_en_priv *priv)
ring = &priv->rx_ring[ring_ind];
if (mlx4_en_prepare_rx_desc(priv, ring,
- ring->actual_size)) {
+ ring->actual_size,
+ GFP_KERNEL)) {
if (ring->actual_size < MLX4_EN_MIN_RX_SIZE) {
en_err(priv, "Failed to allocate "
"enough rx buffers\n");
@@ -450,11 +476,11 @@ static int mlx4_en_complete_rx_desc(struct mlx4_en_priv *priv,
DMA_FROM_DEVICE);
/* Save page reference in skb */
- get_page(frags[nr].page);
__skb_frag_set_page(&skb_frags_rx[nr], frags[nr].page);
skb_frag_size_set(&skb_frags_rx[nr], frag_info->frag_size);
skb_frags_rx[nr].page_offset = frags[nr].offset;
skb->truesize += frag_info->frag_stride;
+ frags[nr].page = NULL;
}
/* Adjust size of last fragment to match actual length */
if (nr > 0)
@@ -547,7 +573,7 @@ static void mlx4_en_refill_rx_buffers(struct mlx4_en_priv *priv,
int index = ring->prod & ring->size_mask;
while ((u32) (ring->prod - ring->cons) < ring->actual_size) {
- if (mlx4_en_prepare_rx_desc(priv, ring, index))
+ if (mlx4_en_prepare_rx_desc(priv, ring, index, GFP_ATOMIC))
break;
ring->prod++;
index = ring->prod & ring->size_mask;
@@ -805,21 +831,7 @@ int mlx4_en_poll_rx_cq(struct napi_struct *napi, int budget)
return done;
}
-
-/* Calculate the last offset position that accommodates a full fragment
- * (assuming fagment size = stride-align) */
-static int mlx4_en_last_alloc_offset(struct mlx4_en_priv *priv, u16 stride, u16 align)
-{
- u16 res = MLX4_EN_ALLOC_SIZE % stride;
- u16 offset = MLX4_EN_ALLOC_SIZE - stride - res + align;
-
- en_dbg(DRV, priv, "Calculated last offset for stride:%d align:%d "
- "res:%d offset:%d\n", stride, align, res, offset);
- return offset;
-}
-
-
-static int frag_sizes[] = {
+static const int frag_sizes[] = {
FRAG_SZ0,
FRAG_SZ1,
FRAG_SZ2,
@@ -847,9 +859,6 @@ void mlx4_en_calc_rx_buf(struct net_device *dev)
priv->frag_info[i].frag_stride =
ALIGN(frag_sizes[i], SMP_CACHE_BYTES);
}
- priv->frag_info[i].last_offset = mlx4_en_last_alloc_offset(
- priv, priv->frag_info[i].frag_stride,
- priv->frag_info[i].frag_align);
buf_size += priv->frag_info[i].frag_size;
i++;
}
@@ -861,13 +870,13 @@ void mlx4_en_calc_rx_buf(struct net_device *dev)
en_dbg(DRV, priv, "Rx buffer scatter-list (effective-mtu:%d "
"num_frags:%d):\n", eff_mtu, priv->num_frags);
for (i = 0; i < priv->num_frags; i++) {
- en_dbg(DRV, priv, " frag:%d - size:%d prefix:%d align:%d "
- "stride:%d last_offset:%d\n", i,
- priv->frag_info[i].frag_size,
- priv->frag_info[i].frag_prefix_size,
- priv->frag_info[i].frag_align,
- priv->frag_info[i].frag_stride,
- priv->frag_info[i].last_offset);
+ en_err(priv,
+ " frag:%d - size:%d prefix:%d align:%d stride:%d\n",
+ i,
+ priv->frag_info[i].frag_size,
+ priv->frag_info[i].frag_prefix_size,
+ priv->frag_info[i].frag_align,
+ priv->frag_info[i].frag_stride);
}
}
diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index 57192a8..35fb60e 100644
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -96,7 +96,8 @@
/* Use the maximum between 16384 and a single page */
#define MLX4_EN_ALLOC_SIZE PAGE_ALIGN(16384)
-#define MLX4_EN_ALLOC_ORDER get_order(MLX4_EN_ALLOC_SIZE)
+
+#define MLX4_EN_ALLOC_PREFER_ORDER PAGE_ALLOC_COSTLY_ORDER
/* Receive fragment sizes; we use at most 3 fragments (for 9600 byte MTU
* and 4K allocations) */
@@ -234,9 +235,10 @@ struct mlx4_en_tx_desc {
#define MLX4_EN_CX3_HIGH_ID 0x1005
struct mlx4_en_rx_alloc {
- struct page *page;
- dma_addr_t dma;
- u16 offset;
+ struct page *page;
+ dma_addr_t dma;
+ u32 offset;
+ u32 size;
};
struct mlx4_en_tx_ring {
@@ -439,8 +441,6 @@ struct mlx4_en_frag_info {
u16 frag_prefix_size;
u16 frag_stride;
u16 frag_align;
- u16 last_offset;
-
};
#ifdef CONFIG_MLX4_EN_DCB
--
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