Adaptive replay of packets in a peripheral interface link

1 . A device comprising a peripheral interface configured to connect to a host system using a peripheral interface protocol, wherein:

the peripheral interface protocol comprises a data link layer configured to transmit and receive data link packets; and

the peripheral interface comprises:

a replay buffer memory configured to store received data link packets following a packet in error to support a selective replay mode; and

a replay logic circuit configured to:

determine an error in a data link packet received through the peripheral interface;

dynamically determine an adaptive threshold for selecting a replay mode based on a set of link operating parameters;

select, based on comparing a fill level of the replay buffer memory to the adaptive threshold, a replay mode selected from:

the selective replay mode for requesting retransmission of only the data link packet in error; and

a sequential replay mode for requesting retransmission of the data link packet in error and subsequent data link packets sent after the data link packet in error; and

send, based on the selected replay mode, a replay request to the host system.

2 . The device of claim 1 , wherein the replay logic circuit is further configured to:

responsive to the selective replay mode:

store, in the replay buffer memory, sequential data link packets without errors received after the data link packet in error;

sequentially send, responsive to receiving an error-free version of the data link packet in error from the host system, transaction layer content from the error-free version of the data link packet in error and the sequential data link packets without errors in the replay buffer memory; and

clear the sequential data link packets without errors from the replay buffer memory; and

responsive to the sequential replay mode:

discard sequential data link packets received after the data link packet in error; and

sequentially send, responsive to receiving the error-free version of the data link packet in error and resent sequential data link packets received after the error-free version of the data link packet in error, transaction layer content from the error-free version of the data link packet in error and the resent sequential data link packets.

3 . The device of claim 1 , wherein:

the replay buffer memory has a buffer size corresponding to a total number of data link packets that can be stored in the replay buffer memory at a time;

the fill level corresponds to a current number of data link packets stored in the replay buffer memory for pending selective replay requests;

the adaptive threshold corresponds to a maximum fill level that is less than the buffer size of the replay buffer memory; and

the replay logic circuit is further configured to periodically determine the adaptive threshold from a plurality of maximum fill levels based on the set of link operating parameters.

4 . The device of claim 3 , wherein:

the peripheral interface protocol supports a flow control mode configured to vary a memory size and format of the data link packets; and

the replay logic circuit is further configured to:

determine that the flow control mode is active;

determine the fill level of the replay buffer memory based on the memory size and format of the data link packets in the flow control mode; and

dynamically determine the adaptive threshold based on the flow control mode.

5 . The device of claim 1 , wherein the replay logic circuit is further configured to, responsive to each detection of a data link packet in error, recalculate the adaptive threshold based on a current set of link operating parameters to dynamically determine the adaptive threshold for that data link packet in error.

6 . The device of claim 1 , wherein the replay logic circuit is further configured to dynamically determine the adaptive threshold by processing the set of link operating parameters through a statistical model comprised of the set of link operating parameters and corresponding weighting factors configured to balance a likelihood of successfully recovering the data link packet in error with data link layer latency.

7 . The device of claim 1 , wherein the set of link operating parameters comprises at least one link connection parameter selected from:

current link speed;

number of lanes; and

bit error rate for the current link speed and number of lanes.

8 . The device of claim 1 , wherein the set of link operating parameters comprises at least one link workload parameter selected from:

a current data link packet workload volume;

a host system historical workload volume; and

a predictive workload volume.

9 . The device of claim 1 , wherein:

the peripheral interface protocol supports a skip ordered set mode configured to periodically resynchronize the data link layer by introducing idle time between fixed periods of transaction layer packet processing;

the link set of operating parameters comprises a counter for the fixed periods of transaction layer packet processing; and

responsive to the skip ordered set mode, dynamically determining the adaptive threshold includes compensation for predicted idle time based on the counter.

10 . The device of claim 1 , wherein the device is a data storage device further comprising:

a non-volatile storage medium configured to store data for the host system; and

a peripheral interface connector configured to connect to a peripheral interface bus for storage communication with the host system using the peripheral interface protocol.

11 . A computer-implemented method, comprising:

receiving, by a peripheral interface circuit, data link packets from a host system through a peripheral interface using a peripheral interface protocol;

determining, by the peripheral interface circuit, an error in a data link packet received through the peripheral interface;

dynamically determining, by the peripheral interface circuit, an adaptive threshold for selecting a replay mode based on a set of link operating parameters;

selecting, by the peripheral interface circuit and based on comparing a fill level of a replay buffer memory to the adaptive threshold, a replay mode selected from:

a selective replay mode for requesting retransmission of only the data link packet in error; and

a sequential replay mode for requesting retransmission of the data link packet in error and subsequent data link packets sent after the data link packet in error; and

sending, by the peripheral interface circuit and based on the selected replay mode, a replay request to the host system.

12 . The computer-implemented method of claim 11 , further comprising:

responsive to the selective replay mode:

storing, by the peripheral interface circuit and in the replay buffer memory, sequential data link packets without errors received after the data link packet in error;

sequentially sending, by the peripheral interface circuit and responsive to receiving an error-free version of the data link packet in error from the host system, transaction layer content from the error-free version of the data link packet in error and the sequential data link packets without errors in the replay buffer memory; and

clearing, by the peripheral interface circuit, the sequential data link packets without errors from the replay buffer memory; and

responsive to the sequential replay mode:

discarding, by the peripheral interface circuit, sequential data link packets received after the data link packet in error; and

sequentially sending, by the peripheral interface circuit and responsive to receiving the error-free version of the data link packet in error and resent sequential data link packets received after the error-free version of the data link packet in error, transaction layer content from the error-free version of the data link packet in error and the resent sequential data link packets.

13 . The computer-implemented method of claim 11 , further comprising:

periodically determining, by the peripheral interface circuit, the adaptive threshold from a plurality of maximum fill levels based on the set of link operating parameters, wherein:

the replay buffer memory has a buffer size corresponding to a total number of data link packets that can be stored in the replay buffer memory at a time;

the fill level corresponds to a current number of data link packets stored in the replay buffer memory for pending selective replay requests; and

the adaptive threshold corresponds to a maximum fill level that is less than the buffer size of the replay buffer memory.

14 . The computer-implemented method of claim 13 , further comprising:

determining, by the peripheral interface circuit, that a flow control mode is active, wherein the peripheral interface protocol supports the flow control mode configured to vary a memory size and format of the data link packets;

determining, by the peripheral interface circuit, the fill level of the replay buffer memory based on the memory size and format of the data link packets in the flow control mode; and

dynamically determining, by the peripheral interface circuit, the adaptive threshold based on the flow control mode.

15 . The computer-implemented method of claim 11 , further comprising, responsive to each detection of a data link packet in error:

recalculating, by the peripheral interface circuit, the adaptive threshold based on a current set of link operating parameters to dynamically determine the adaptive threshold for that data link packet in error.

16 . The computer-implemented method of claim 11 , further comprising:

processing, by the peripheral interface circuit, the set of link operating parameters through a statistical model comprised of the set of link operating parameters and corresponding weighting factors configured to balance a likelihood of successfully recovering the data link packet in error with data link layer latency.

17 . The computer-implemented method of claim 11 , wherein the set of link operating parameters comprises at least one link connection parameter selected from:

current link speed;

number of lanes; and

bit error rate for the current link speed and number of lanes.

18 . The computer-implemented method of claim 11 , wherein the set of link operating parameters comprises at least one link workload parameter selected from:

a current data link packet workload volume;

a host system historical workload volume; and

a predictive workload volume.

19 . The computer-implemented method of claim 11 , wherein:

the peripheral interface protocol supports a skip ordered set mode configured to periodically resynchronize a data link layer by introducing idle time between fixed periods of transaction layer packet processing;

the link set of operating parameters comprises a counter for the fixed periods of transaction layer packet processing; and

responsive to the skip ordered set mode, dynamically determining the adaptive threshold includes compensation for predicted idle time based on the counter.

20 . A peripheral interface circuit comprising:

at least one processor;

a memory;

a data link layer configured to receive data link packets from a host system;

a replay buffer memory configured to store received data link packets following a packet in error to support a selective replay mode;

means, stored in the memory for execution by the at least one processor, for determining an error in a data link packet received from the host system;

means, stored in the memory for execution by the at least one processor, for dynamically determining an adaptive threshold for selecting a replay mode based on a set of link operating parameters;

means, stored in the memory for execution by the at least one processor, for selecting, based on comparing a fill level of the replay buffer memory to the adaptive threshold, a replay mode selected from:

the selective replay mode for requesting retransmission of only the data link packet in error; and

a sequential replay mode for requesting retransmission of the data link packet in error and subsequent data link packets sent after the data link packet in error; and

means, stored in the memory for execution by the at least one processor, for sending, based on the selected replay mode, a replay request to the host system.