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Subject[PATCH V2 net-next 1/6] net: hns3: batch the page reference count updates
Date
From: Yunsheng Lin <linyunsheng@huawei.com>

Batch the page reference count updates instead of doing them
one at a time. By doing this we can improve the overall receive
performance by avoid some atomic increment operations when the
rx page is reused.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
---
drivers/net/ethernet/hisilicon/hns3/hns3_enet.c | 32 ++++++++++++++++++-------
drivers/net/ethernet/hisilicon/hns3/hns3_enet.h | 1 +
2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
index 93825a4..3762142 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.c
@@ -2302,6 +2302,8 @@ static int hns3_alloc_buffer(struct hns3_enet_ring *ring,
cb->buf = page_address(p);
cb->length = hns3_page_size(ring);
cb->type = DESC_TYPE_PAGE;
+ page_ref_add(p, USHRT_MAX - 1);
+ cb->pagecnt_bias = USHRT_MAX;

return 0;
}
@@ -2311,8 +2313,8 @@ static void hns3_free_buffer(struct hns3_enet_ring *ring,
{
if (cb->type == DESC_TYPE_SKB)
dev_kfree_skb_any((struct sk_buff *)cb->priv);
- else if (!HNAE3_IS_TX_RING(ring))
- put_page((struct page *)cb->priv);
+ else if (!HNAE3_IS_TX_RING(ring) && cb->pagecnt_bias)
+ __page_frag_cache_drain(cb->priv, cb->pagecnt_bias);
memset(cb, 0, sizeof(*cb));
}

@@ -2610,6 +2612,11 @@ static bool hns3_page_is_reusable(struct page *page)
!page_is_pfmemalloc(page);
}

+static bool hns3_can_reuse_page(struct hns3_desc_cb *cb)
+{
+ return (page_count(cb->priv) - cb->pagecnt_bias) == 1;
+}
+
static void hns3_nic_reuse_page(struct sk_buff *skb, int i,
struct hns3_enet_ring *ring, int pull_len,
struct hns3_desc_cb *desc_cb)
@@ -2618,6 +2625,7 @@ static void hns3_nic_reuse_page(struct sk_buff *skb, int i,
int size = le16_to_cpu(desc->rx.size);
u32 truesize = hns3_buf_size(ring);

+ desc_cb->pagecnt_bias--;
skb_add_rx_frag(skb, i, desc_cb->priv, desc_cb->page_offset + pull_len,
size - pull_len, truesize);

@@ -2625,20 +2633,27 @@ static void hns3_nic_reuse_page(struct sk_buff *skb, int i,
* when page_offset rollback to zero, flag default unreuse
*/
if (unlikely(!hns3_page_is_reusable(desc_cb->priv)) ||
- (!desc_cb->page_offset && page_count(desc_cb->priv) > 1))
+ (!desc_cb->page_offset && !hns3_can_reuse_page(desc_cb))) {
+ __page_frag_cache_drain(desc_cb->priv, desc_cb->pagecnt_bias);
return;
+ }

/* Move offset up to the next cache line */
desc_cb->page_offset += truesize;

if (desc_cb->page_offset + truesize <= hns3_page_size(ring)) {
desc_cb->reuse_flag = 1;
- /* Bump ref count on page before it is given */
- get_page(desc_cb->priv);
- } else if (page_count(desc_cb->priv) == 1) {
+ } else if (hns3_can_reuse_page(desc_cb)) {
desc_cb->reuse_flag = 1;
desc_cb->page_offset = 0;
- get_page(desc_cb->priv);
+ } else if (desc_cb->pagecnt_bias) {
+ __page_frag_cache_drain(desc_cb->priv, desc_cb->pagecnt_bias);
+ return;
+ }
+
+ if (unlikely(!desc_cb->pagecnt_bias)) {
+ page_ref_add(desc_cb->priv, USHRT_MAX);
+ desc_cb->pagecnt_bias = USHRT_MAX;
}
}

@@ -2846,7 +2861,8 @@ static int hns3_alloc_skb(struct hns3_enet_ring *ring, unsigned int length,
if (likely(hns3_page_is_reusable(desc_cb->priv)))
desc_cb->reuse_flag = 1;
else /* This page cannot be reused so discard it */
- put_page(desc_cb->priv);
+ __page_frag_cache_drain(desc_cb->priv,
+ desc_cb->pagecnt_bias);

ring_ptr_move_fw(ring, next_to_clean);
return 0;
diff --git a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
index 98ca6ea..8f784094 100644
--- a/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
+++ b/drivers/net/ethernet/hisilicon/hns3/hns3_enet.h
@@ -287,6 +287,7 @@ struct hns3_desc_cb {

/* desc type, used by the ring user to mark the type of the priv data */
u16 type;
+ u16 pagecnt_bias;
};

enum hns3_pkt_l3type {
--
2.7.4
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