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Date: Mon, 5 Dec 2016 13:54:50 -0800
From: Alexander Duyck <alexander.duyck@...il.com>
To: Tushar Dave <tushar.n.dave@...cle.com>
Cc: Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
Netdev <netdev@...r.kernel.org>
Subject: Re: [Intel-wired-lan] [RFC PATCH] i40e: enable PCIe relax ordering
for SPARC
On Mon, Dec 5, 2016 at 9:07 AM, Tushar Dave <tushar.n.dave@...cle.com> wrote:
> Unlike previous generation NIC (e.g. ixgbe) i40e doesn't seem to have
> standard CSR where PCIe relaxed ordering can be set. Without PCIe relax
> ordering enabled, i40e performance is significantly low on SPARC.
>
> This patch sets PCIe relax ordering for SPARC arch by setting dma attr
> DMA_ATTR_WEAK_ORDERING for every tx and rx DMA map/unmap.
> This has shown 10x increase in performance numbers.
>
> e.g.
> iperf TCP test with 10 threads on SPARC S7
>
> Test 1: Without this patch
>
> [root@...-snt1-03 net]# iperf -s
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size: 85.3 KByte (default)
> ------------------------------------------------------------
> [ 4] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40926
> [ 5] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40934
> [ 6] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40930
> [ 7] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40928
> [ 8] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40922
> [ 9] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40932
> [ 10] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40920
> [ 11] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40924
> [ 14] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40982
> [ 12] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 40980
> [ ID] Interval Transfer Bandwidth
> [ 4] 0.0-20.0 sec 566 MBytes 237 Mbits/sec
> [ 5] 0.0-20.0 sec 532 MBytes 223 Mbits/sec
> [ 6] 0.0-20.0 sec 537 MBytes 225 Mbits/sec
> [ 8] 0.0-20.0 sec 546 MBytes 229 Mbits/sec
> [ 11] 0.0-20.0 sec 592 MBytes 248 Mbits/sec
> [ 7] 0.0-20.0 sec 539 MBytes 226 Mbits/sec
> [ 9] 0.0-20.0 sec 572 MBytes 240 Mbits/sec
> [ 10] 0.0-20.0 sec 604 MBytes 253 Mbits/sec
> [ 14] 0.0-20.0 sec 567 MBytes 238 Mbits/sec
> [ 12] 0.0-20.0 sec 511 MBytes 214 Mbits/sec
> [SUM] 0.0-20.0 sec 5.44 GBytes 2.33 Gbits/sec
>
> Test 2: with this patch:
>
> [root@...-snt1-03 net]# iperf -s
> ------------------------------------------------------------
> Server listening on TCP port 5001
> TCP window size: 85.3 KByte (default)
> ------------------------------------------------------------
> TCP: request_sock_TCP: Possible SYN flooding on port 5001. Sending
> cookies. Check SNMP counters.
> [ 4] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46876
> [ 5] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46874
> [ 6] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46872
> [ 7] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46880
> [ 8] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46878
> [ 9] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46884
> [ 10] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46886
> [ 11] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46890
> [ 12] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46888
> [ 13] local 16.0.0.7 port 5001 connected with 16.0.0.1 port 46882
> [ ID] Interval Transfer Bandwidth
> [ 4] 0.0-20.0 sec 7.45 GBytes 3.19 Gbits/sec
> [ 5] 0.0-20.0 sec 7.48 GBytes 3.21 Gbits/sec
> [ 7] 0.0-20.0 sec 7.34 GBytes 3.15 Gbits/sec
> [ 8] 0.0-20.0 sec 7.42 GBytes 3.18 Gbits/sec
> [ 9] 0.0-20.0 sec 7.24 GBytes 3.11 Gbits/sec
> [ 10] 0.0-20.0 sec 7.40 GBytes 3.17 Gbits/sec
> [ 12] 0.0-20.0 sec 7.49 GBytes 3.21 Gbits/sec
> [ 6] 0.0-20.0 sec 7.30 GBytes 3.13 Gbits/sec
> [ 11] 0.0-20.0 sec 7.44 GBytes 3.19 Gbits/sec
> [ 13] 0.0-20.0 sec 7.22 GBytes 3.10 Gbits/sec
> [SUM] 0.0-20.0 sec 73.8 GBytes 31.6 Gbits/sec
>
> NOTE: In my testing, this patch does _not_ show any harm to i40e
> performance numbers on x86.
>
> Signed-off-by: Tushar Dave <tushar.n.dave@...cle.com>
You went through and replaced all of the dma_unmap/map_page calls with
dma_map/unmap_single_attrs I would prefer you didn't do that. I have
patches to add the ability to map and unmap pages with attributes that
should be available for 4.10-rc1 so if you could wait on this patch
until then it would be preferred.
> ---
> drivers/net/ethernet/intel/i40e/i40e_txrx.c | 69 ++++++++++++++++++++---------
> drivers/net/ethernet/intel/i40e/i40e_txrx.h | 1 +
> 2 files changed, 49 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> index 6287bf6..800dca7 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
> @@ -551,15 +551,17 @@ static void i40e_unmap_and_free_tx_resource(struct i40e_ring *ring,
> else
> dev_kfree_skb_any(tx_buffer->skb);
> if (dma_unmap_len(tx_buffer, len))
> - dma_unmap_single(ring->dev,
> - dma_unmap_addr(tx_buffer, dma),
> - dma_unmap_len(tx_buffer, len),
> - DMA_TO_DEVICE);
> + dma_unmap_single_attrs(ring->dev,
> + dma_unmap_addr(tx_buffer, dma),
> + dma_unmap_len(tx_buffer, len),
> + DMA_TO_DEVICE,
> + ring->dma_attrs);
> } else if (dma_unmap_len(tx_buffer, len)) {
> - dma_unmap_page(ring->dev,
> - dma_unmap_addr(tx_buffer, dma),
> - dma_unmap_len(tx_buffer, len),
> - DMA_TO_DEVICE);
> + dma_unmap_single_attrs(ring->dev,
> + dma_unmap_addr(tx_buffer, dma),
> + dma_unmap_len(tx_buffer, len),
> + DMA_TO_DEVICE,
> + ring->dma_attrs);
> }
>
> tx_buffer->next_to_watch = NULL;
> @@ -662,6 +664,8 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
> struct i40e_tx_buffer *tx_buf;
> struct i40e_tx_desc *tx_head;
> struct i40e_tx_desc *tx_desc;
> + dma_addr_t addr;
> + size_t size;
> unsigned int total_bytes = 0, total_packets = 0;
> unsigned int budget = vsi->work_limit;
>
> @@ -696,10 +700,11 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
> napi_consume_skb(tx_buf->skb, napi_budget);
>
> /* unmap skb header data */
> - dma_unmap_single(tx_ring->dev,
> - dma_unmap_addr(tx_buf, dma),
> - dma_unmap_len(tx_buf, len),
> - DMA_TO_DEVICE);
> + dma_unmap_single_attrs(tx_ring->dev,
> + dma_unmap_addr(tx_buf, dma),
> + dma_unmap_len(tx_buf, len),
> + DMA_TO_DEVICE,
> + tx_ring->dma_attrs);
>
> /* clear tx_buffer data */
> tx_buf->skb = NULL;
> @@ -717,12 +722,15 @@ static bool i40e_clean_tx_irq(struct i40e_vsi *vsi,
> tx_desc = I40E_TX_DESC(tx_ring, 0);
> }
>
> + addr = dma_unmap_addr(tx_buf, dma);
> + size = dma_unmap_len(tx_buf, len);
On some architectures this change could lead to issues since
dma_unmap_len could be 0 meaning that addr would never be used.
> /* unmap any remaining paged data */
> if (dma_unmap_len(tx_buf, len)) {
> - dma_unmap_page(tx_ring->dev,
> - dma_unmap_addr(tx_buf, dma),
> - dma_unmap_len(tx_buf, len),
> - DMA_TO_DEVICE);
> + dma_unmap_single_attrs(tx_ring->dev,
> + addr,
> + size,
> + DMA_TO_DEVICE,
> + tx_ring->dma_attrs);
> dma_unmap_len_set(tx_buf, len, 0);
> }
> }
> @@ -1010,6 +1018,11 @@ int i40e_setup_tx_descriptors(struct i40e_ring *tx_ring)
> */
> tx_ring->size += sizeof(u32);
> tx_ring->size = ALIGN(tx_ring->size, 4096);
> +#ifdef CONFIG_SPARC
> + tx_ring->dma_attrs = DMA_ATTR_WEAK_ORDERING;
> +#else
> + tx_ring->dma_attrs = 0;
> +#endif
> tx_ring->desc = dma_alloc_coherent(dev, tx_ring->size,
> &tx_ring->dma, GFP_KERNEL);
> if (!tx_ring->desc) {
Also not a fan of adding yet ring attribute. Is there any reason why
you couldn't simply add a set of inline functions at the start of
i40e_txrx.c that could replace the DMA map/unmap operations in this
code but pass either 0 or DMA_ATTR_WEAK_ORDERING as needed for the
drivers? Then the x86 code doesn't have to change while the SPARC
code will be able to be passed the attribute.
> @@ -1053,7 +1066,11 @@ void i40e_clean_rx_ring(struct i40e_ring *rx_ring)
> if (!rx_bi->page)
> continue;
>
> - dma_unmap_page(dev, rx_bi->dma, PAGE_SIZE, DMA_FROM_DEVICE);
> + dma_unmap_single_attrs(dev,
> + rx_bi->dma,
> + PAGE_SIZE,
> + DMA_FROM_DEVICE,
> + rx_ring->dma_attrs);
> __free_pages(rx_bi->page, 0);
>
> rx_bi->page = NULL;
> @@ -1113,6 +1130,11 @@ int i40e_setup_rx_descriptors(struct i40e_ring *rx_ring)
> /* Round up to nearest 4K */
> rx_ring->size = rx_ring->count * sizeof(union i40e_32byte_rx_desc);
> rx_ring->size = ALIGN(rx_ring->size, 4096);
> +#ifdef CONFIG_SPARC
> + rx_ring->dma_attrs = DMA_ATTR_WEAK_ORDERING;
> +#else
> + rx_ring->dma_attrs = 0;
> +#endif
> rx_ring->desc = dma_alloc_coherent(dev, rx_ring->size,
> &rx_ring->dma, GFP_KERNEL);
>
> @@ -1182,7 +1204,8 @@ static bool i40e_alloc_mapped_page(struct i40e_ring *rx_ring,
> }
>
> /* map page for use */
> - dma = dma_map_page(rx_ring->dev, page, 0, PAGE_SIZE, DMA_FROM_DEVICE);
> + dma = dma_map_single_attrs(rx_ring->dev, page_address(page), PAGE_SIZE,
> + DMA_FROM_DEVICE, rx_ring->dma_attrs);
>
> /* if mapping failed free memory back to system since
> * there isn't much point in holding memory we can't use
> @@ -1695,8 +1718,11 @@ struct sk_buff *i40e_fetch_rx_buffer(struct i40e_ring *rx_ring,
> rx_ring->rx_stats.page_reuse_count++;
> } else {
> /* we are not reusing the buffer so unmap it */
> - dma_unmap_page(rx_ring->dev, rx_buffer->dma, PAGE_SIZE,
> - DMA_FROM_DEVICE);
> + dma_unmap_single_attrs(rx_ring->dev,
> + rx_buffer->dma,
> + PAGE_SIZE,
> + DMA_FROM_DEVICE,
> + rx_ring->dma_attrs);
> }
>
> /* clear contents of buffer_info */
> @@ -2737,7 +2763,8 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
> first->skb = skb;
> first->tx_flags = tx_flags;
>
> - dma = dma_map_single(tx_ring->dev, skb->data, size, DMA_TO_DEVICE);
> + dma = dma_map_single_attrs(tx_ring->dev, skb->data, size,
> + DMA_TO_DEVICE, tx_ring->dma_attrs);
>
> tx_desc = I40E_TX_DESC(tx_ring, i);
> tx_bi = first;
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.h b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
> index 5088405..9a86212 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_txrx.h
> +++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.h
> @@ -327,6 +327,7 @@ struct i40e_ring {
>
> unsigned int size; /* length of descriptor ring in bytes */
> dma_addr_t dma; /* physical address of ring */
> + unsigned long dma_attrs; /* DMA attributes */
>
> struct i40e_vsi *vsi; /* Backreference to associated VSI */
> struct i40e_q_vector *q_vector; /* Backreference to associated vector */
> --
> 1.9.1
>
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