diff mbox series

net/nfp: fix minimum descriptor sizes

Message ID 20210823075921.97168-1-heinrich.kuhn@corigine.com (mailing list archive)
State Accepted, archived
Delegated to: Ferruh Yigit
Headers
Series net/nfp: fix minimum descriptor sizes |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/github-robot: build success github build: passed
ci/iol-abi-testing warning Testing issues
ci/iol-broadcom-Performance success Performance Testing PASS
ci/iol-broadcom-Functional success Functional Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-intel-Performance fail Performance Testing issues
ci/iol-x86_64-compile-testing success Testing PASS
ci/iol-aarch64-compile-testing success Testing PASS
ci/Intel-compilation success Compilation OK
ci/intel-Testing success Testing PASS
ci/iol-mellanox-Performance fail Performance Testing issues
ci/iol-x86_64-unit-testing success Testing PASS
ci/iol-aarch64-unit-testing success Testing PASS

Commit Message

heinrich.kuhn@corigine.com Aug. 23, 2021, 7:59 a.m. UTC 
  From: Heinrich Kuhn <heinrich.kuhn@corigine.com>

The NFP4000/6000 supports a minimum of 256 Tx/Rx descriptors and not 64.
Before this patch when a DPDK application configured < 256 Tx
descriptors the hardware read/write pointers would be unmasked and not
wrapped at the expected size of the ring. The PMD logic to determine the
amount of free space in the Tx ring is incompatible with the unmasked
hwqueue pointers and this will result in the PMD not updating the
read pointer at all.The knock-on effect is that under high load the
PMD will potentially re-use a Tx descriptor before the hw has had a
chance to process that particular descriptor. This issue can manifest as
a DMA error when the hardware tries to perform a DMA with info from a
partially populated descriptor.

Fixes: defb9a5dd156 ("nfp: introduce driver initialization")
Cc: stable@dpdk.org

Signed-off-by: Heinrich Kuhn <heinrich.kuhn@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
---
 drivers/net/nfp/nfp_rxtx.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Ferruh Yigit Aug. 31, 2021, 3:57 p.m. UTC | #1 
On 8/23/2021 8:59 AM, heinrich.kuhn@corigine.com wrote:
> From: Heinrich Kuhn <heinrich.kuhn@corigine.com>
> 
> The NFP4000/6000 supports a minimum of 256 Tx/Rx descriptors and not 64.
> Before this patch when a DPDK application configured < 256 Tx
> descriptors the hardware read/write pointers would be unmasked and not
> wrapped at the expected size of the ring. The PMD logic to determine the
> amount of free space in the Tx ring is incompatible with the unmasked
> hwqueue pointers and this will result in the PMD not updating the
> read pointer at all.The knock-on effect is that under high load the
> PMD will potentially re-use a Tx descriptor before the hw has had a
> chance to process that particular descriptor. This issue can manifest as
> a DMA error when the hardware tries to perform a DMA with info from a
> partially populated descriptor.
> 
> Fixes: defb9a5dd156 ("nfp: introduce driver initialization")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Heinrich Kuhn <heinrich.kuhn@corigine.com>
> Signed-off-by: Simon Horman <simon.horman@corigine.com>

Applied to dpdk-next-net/main, thanks.
diff mbox series

Patch

diff --git a/drivers/net/nfp/nfp_rxtx.h b/drivers/net/nfp/nfp_rxtx.h
index d2d0f3f175..b0a8bf81b0 100644
--- a/drivers/net/nfp/nfp_rxtx.h
+++ b/drivers/net/nfp/nfp_rxtx.h
@@ -30,10 +30,10 @@ 
  * DPDK uses uint16_t variables for these values
  */
 #define NFP_NET_MAX_TX_DESC (32 * 1024)
-#define NFP_NET_MIN_TX_DESC 64
+#define NFP_NET_MIN_TX_DESC 256
 
 #define NFP_NET_MAX_RX_DESC (32 * 1024)
-#define NFP_NET_MIN_RX_DESC 64
+#define NFP_NET_MIN_RX_DESC 256
 
 /* Descriptor alignment */
 #define NFP_ALIGN_RING_DESC 128