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mvpp2: prefetch page

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Most of the time during the RX is caused by the compound_head() call
done at the end of the RX loop:

       │     build_skb():
       [...]
       │     static inline struct page *compound_head(struct page *page)
       │     {
       │     unsigned long head = READ_ONCE(page->compound_head);
 65.23 │       ldr  x2, [x1, #8]

Prefetch the page struct as soon as possible, to speedup the RX path
noticeabily by a ~3-4% packet rate in a drop test.

       │     build_skb():
       [...]
       │     static inline struct page *compound_head(struct page *page)
       │     {
       │     unsigned long head = READ_ONCE(page->compound_head);
 17.92 │       ldr  x2, [x1, #8]

Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Matteo Croce 2021-06-09 15:47:14 +02:00 committed by David S. Miller
parent d8ea89fe8a
commit 2f128eb330
1 changed files with 7 additions and 3 deletions
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10
drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
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@ -3900,15 +3900,19 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi,
phys_addr_t phys_addr;
u32 rx_status, timestamp;
int pool, rx_bytes, err, ret;
struct page *page;
void *data;
phys_addr = mvpp2_rxdesc_cookie_get(port, rx_desc);
data = (void *)phys_to_virt(phys_addr);
page = virt_to_page(data);
prefetch(page);
rx_done++;
rx_status = mvpp2_rxdesc_status_get(port, rx_desc);
rx_bytes = mvpp2_rxdesc_size_get(port, rx_desc);
rx_bytes -= MVPP2_MH_SIZE;
dma_addr = mvpp2_rxdesc_dma_addr_get(port, rx_desc);
phys_addr = mvpp2_rxdesc_cookie_get(port, rx_desc);
data = (void *)phys_to_virt(phys_addr);
pool = (rx_status & MVPP2_RXD_BM_POOL_ID_MASK) >>
MVPP2_RXD_BM_POOL_ID_OFFS;
@ -3997,7 +4001,7 @@ static int mvpp2_rx(struct mvpp2_port *port, struct napi_struct *napi,
}
if (pp)
skb_mark_for_recycle(skb, virt_to_page(data), pp);
skb_mark_for_recycle(skb, page, pp);
else
dma_unmap_single_attrs(dev->dev.parent, dma_addr,
bm_pool->buf_size, DMA_FROM_DEVICE,