[Intel-wired-lan] [RFC PATCH] i40e: enable PCIe relax ordering for SPARC

tndave tushar.n.dave at oracle.com
Mon Dec 5 22:23:59 UTC 2016



On 12/05/2016 01:54 PM, Alexander Duyck wrote:
> On Mon, Dec 5, 2016 at 9:07 AM, Tushar Dave <tushar.n.dave at oracle.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
>>
>> # 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:
>>
>> # 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 at oracle.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
Yes, because currently there is no DMA API for dma_map/unmap_page with 
dma attr*
> 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.
:-) thanks. I will wait until your patches are out.
>
>> ---
>>  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.
I see. Thanks.
>
>>                         /* 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.
Sure I can do that.

I will follow up with patch after your patches for map/unmap page with 
dma attr will be out.

Thanks.

-Tushar
>
>> @@ -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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>


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