http://bugs.dpdk.org/show_bug.cgi?id=1898
Bug ID: 1898
Summary: net/iavf: random packet reception delays with
RTE_ETH_RX_OFFLOAD_TIMESTAMP
Product: DPDK
Version: unspecified
Hardware: All
OS: All
Status: UNCONFIRMED
Severity: normal
Priority: Normal
Component: other
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Random latency for some packets has been observed when polling from some IAVF
device.
The PF driver is a RHEL9.6 kernel ice driver.
This issue was observed after a kernel upgrade and bisecting points at kernel
commit "7c1178a9df58 ("ice: support Rx timestamp on flex descriptor")".
Our understanding is that following this change, the PF announces the
VIRTCHNL_VF_CAP_PTP capability, which then allows using
RTE_ETH_RX_OFFLOAD_TIMESTAMP on the DPDK driver side.
Disabling RTE_ETH_RX_OFFLOAD_TIMESTAMP on the application side made the random
latency issue disappear.
Looking at the Rx path for the iavf driver, a (frequent) call to
iavf_get_phc_time() can be noticed which is likely the cause of the random
slowdowns.
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