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

[maowenan <maowenan@huawei.com>]

> -----Original Message-----
> From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.org]
> On Behalf Of Alexander Duyck
> Sent: Tuesday, December 06, 2016 5:55 AM
> To: Tushar Dave
> Cc: Jeff Kirsher; intel-wired-lan; Netdev
> 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@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
> >
> > [root@brm-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@brm-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@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
> 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.
> 
[Mao Wenan] Have you already sent out the related patches? I want to refer to
you how to enable this ability, then we can adopt it to configure relax ordering 
through DCA control register on device 82599.
Thank you.

> > ---
> >  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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> > Intel-wired-lan@lists.osuosl.org
> > http://lists.osuosl.org/mailman/listinfo/intel-wired-lan