[dpdk-dev] [PATCH v2 0/3] net: fix out of order Rx read issue

[dpdk-dev] [PATCH v2 0/3] net: fix out of order Rx read issue

[Qi Zhang]

In vPMD, when load Rx desc with _mm_loadu_si128, 
volatile point will be cast into non-volatile point.
So GCC is allowed to reorder the load instructions, 
while Rx read's correctness is reply on these load 
instructions to follow a backward sequence strictly, 
so we add compile barrier to prevent compiler reorder.
We already met this issue on i40e with GCC6 and we 
fixed this on ixgbe and fm10k also.

v2: 
- fix check-git-log.sh warning.
- add more detail commit message.

Qi Zhang (3):
  net/i40e: fix out of order Rx read issue
  net/ixgbe: fix out of order Rx read issue
  net/fm10k: fix out of ofder Rx read issue

 drivers/net/fm10k/fm10k_rxtx_vec.c     | 3 +++
 drivers/net/i40e/i40e_rxtx_vec.c       | 3 +++
 drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c | 3 +++
 3 files changed, 9 insertions(+)

-- 
2.7.4

[dpdk-dev] [PATCH v2 1/3] net/i40e: fix out of order Rx read issue

[Qi Zhang]

In vPMD, when load Rx desc with _mm_loadu_si128,
volatile point will be cast into non-volatile point.
So GCC is allowed to reorder the load instructions,
while Rx read's correctness is reply on these load
instructions to follow a backward sequence strictly,
so we add compile barrier to prevent compiler reorder.

Fixes: 9ed94e5bb04e ("i40e: add vector Rx")

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
---

v2:
- fix check-git-log.sh warning.
- add more detail commit message.

 drivers/net/i40e/i40e_rxtx_vec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/i40e/i40e_rxtx_vec.c b/drivers/net/i40e/i40e_rxtx_vec.c
index 0ee0241..ab63501 100644
--- a/drivers/net/i40e/i40e_rxtx_vec.c
+++ b/drivers/net/i40e/i40e_rxtx_vec.c
@@ -305,6 +305,7 @@ _recv_raw_pkts_vec(struct i40e_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 		/* Read desc statuses backwards to avoid race condition */
 		/* A.1 load 4 pkts desc */
 		descs[3] = _mm_loadu_si128((__m128i *)(rxdp + 3));
+		rte_compiler_barrier();
 
 		/* B.2 copy 2 mbuf point into rx_pkts  */
 		_mm_storeu_si128((__m128i *)&rx_pkts[pos], mbp1);
@@ -313,8 +314,10 @@ _recv_raw_pkts_vec(struct i40e_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 		mbp2 = _mm_loadu_si128((__m128i *)&sw_ring[pos+2]);
 
 		descs[2] = _mm_loadu_si128((__m128i *)(rxdp + 2));
+		rte_compiler_barrier();
 		/* B.1 load 2 mbuf point */
 		descs[1] = _mm_loadu_si128((__m128i *)(rxdp + 1));
+		rte_compiler_barrier();
 		descs[0] = _mm_loadu_si128((__m128i *)(rxdp));
 
 		/* B.2 copy 2 mbuf point into rx_pkts  */
-- 
2.7.4

[dpdk-dev] [PATCH v2 2/3] net/ixgbe: fix out of order Rx read issue

[Qi Zhang]

In vPMD, when load Rx desc with _mm_loadu_si128,
volatile point will be cast into non-volatile point.
So GCC is allowed to reorder the load instructions,
while Rx read's correctness is reply on these load
instructions to follow a backward sequence strictly,
so we add compile barrier to prevent compiler reorder.

Fixes: c95584dc2b18 ("ixgbe: new vectorized functions for Rx/Tx")

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
---

v2:
- fix check-git-log.sh warning.
- add more detail commit message.

 drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
index ad8a9ff..abbf284 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c
@@ -343,6 +343,7 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 		/* Read desc statuses backwards to avoid race condition */
 		/* A.1 load 4 pkts desc */
 		descs[3] = _mm_loadu_si128((__m128i *)(rxdp + 3));
+		rte_compiler_barrier();
 
 		/* B.2 copy 2 mbuf point into rx_pkts  */
 		_mm_storeu_si128((__m128i *)&rx_pkts[pos], mbp1);
@@ -351,8 +352,10 @@ _recv_raw_pkts_vec(struct ixgbe_rx_queue *rxq, struct rte_mbuf **rx_pkts,
 		mbp2 = _mm_loadu_si128((__m128i *)&sw_ring[pos+2]);
 
 		descs[2] = _mm_loadu_si128((__m128i *)(rxdp + 2));
+		rte_compiler_barrier();
 		/* B.1 load 2 mbuf point */
 		descs[1] = _mm_loadu_si128((__m128i *)(rxdp + 1));
+		rte_compiler_barrier();
 		descs[0] = _mm_loadu_si128((__m128i *)(rxdp));
 
 		/* B.2 copy 2 mbuf point into rx_pkts  */
-- 
2.7.4

[dpdk-dev] [PATCH v2 3/3] net/fm10k: fix out of ofder Rx read issue

[Qi Zhang]

In vPMD, when load Rx desc with _mm_loadu_si128,
volatile point will be cast into non-volatile point.
So GCC is allowed to reorder the load instructions,
while Rx read's correctness is reply on these load
instructions to follow a backward sequence strictly,
so we add compile barrier to prevent compiler reorder.

Fixes: 7092be8437bd ("fm10k: add vector Rx")

Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
---

v2:
- fix check-git-log.sh warning.
- add more detail commit message.

 drivers/net/fm10k/fm10k_rxtx_vec.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/fm10k/fm10k_rxtx_vec.c b/drivers/net/fm10k/fm10k_rxtx_vec.c
index b724486..27f3e43 100644
--- a/drivers/net/fm10k/fm10k_rxtx_vec.c
+++ b/drivers/net/fm10k/fm10k_rxtx_vec.c
@@ -478,6 +478,7 @@ fm10k_recv_raw_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
 		/* Read desc statuses backwards to avoid race condition */
 		/* A.1 load 4 pkts desc */
 		descs0[3] = _mm_loadu_si128((__m128i *)(rxdp + 3));
+		rte_compiler_barrier();
 
 		/* B.2 copy 2 mbuf point into rx_pkts  */
 		_mm_storeu_si128((__m128i *)&rx_pkts[pos], mbp1);
@@ -486,8 +487,10 @@ fm10k_recv_raw_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
 		mbp2 = _mm_loadu_si128((__m128i *)&mbufp[pos+2]);
 
 		descs0[2] = _mm_loadu_si128((__m128i *)(rxdp + 2));
+		rte_compiler_barrier();
 		/* B.1 load 2 mbuf point */
 		descs0[1] = _mm_loadu_si128((__m128i *)(rxdp + 1));
+		rte_compiler_barrier();
 		descs0[0] = _mm_loadu_si128((__m128i *)(rxdp));
 
 		/* B.2 copy 2 mbuf point into rx_pkts  */
-- 
2.7.4

Re: [dpdk-dev] [PATCH v2 0/3] net: fix out of order Rx read issue

[Ananyev, Konstantin]

> 
> In vPMD, when load Rx desc with _mm_loadu_si128,
> volatile point will be cast into non-volatile point.
> So GCC is allowed to reorder the load instructions,
> while Rx read's correctness is reply on these load
> instructions to follow a backward sequence strictly,
> so we add compile barrier to prevent compiler reorder.
> We already met this issue on i40e with GCC6 and we
> fixed this on ixgbe and fm10k also.
> 
> v2:
> - fix check-git-log.sh warning.
> - add more detail commit message.
> 
> Qi Zhang (3):
>   net/i40e: fix out of order Rx read issue
>   net/ixgbe: fix out of order Rx read issue
>   net/fm10k: fix out of ofder Rx read issue
> 
>  drivers/net/fm10k/fm10k_rxtx_vec.c     | 3 +++
>  drivers/net/i40e/i40e_rxtx_vec.c       | 3 +++
>  drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c | 3 +++
>  3 files changed, 9 insertions(+)
> 
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 2.7.4

Re: [dpdk-dev] [PATCH v2 0/3] net: fix out of order Rx read issue

[Bruce Richardson]

On Tue, Oct 18, 2016 at 11:33:43AM +0000, Ananyev, Konstantin wrote:
> 
> 
> > 
> > In vPMD, when load Rx desc with _mm_loadu_si128,
> > volatile point will be cast into non-volatile point.
> > So GCC is allowed to reorder the load instructions,
> > while Rx read's correctness is reply on these load
> > instructions to follow a backward sequence strictly,
> > so we add compile barrier to prevent compiler reorder.
> > We already met this issue on i40e with GCC6 and we
> > fixed this on ixgbe and fm10k also.
> > 
> > v2:
> > - fix check-git-log.sh warning.
> > - add more detail commit message.
> > 
> > Qi Zhang (3):
> >   net/i40e: fix out of order Rx read issue
> >   net/ixgbe: fix out of order Rx read issue
> >   net/fm10k: fix out of ofder Rx read issue
> > 
> >  drivers/net/fm10k/fm10k_rxtx_vec.c     | 3 +++
> >  drivers/net/i40e/i40e_rxtx_vec.c       | 3 +++
> >  drivers/net/ixgbe/ixgbe_rxtx_vec_sse.c | 3 +++
> >  3 files changed, 9 insertions(+)
> > 
> > --
> 
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> 
Applied to dpdk-next_net/rel_16_11

/Bruce