From eab9e22d309f965e7b7b4090a62cbde2d8b505cb Mon Sep 17 00:00:00 2001 From: Jessie Yang Date: Mon, 9 Sep 2024 11:42:03 -0700 Subject: [PATCH] [v1.21.x]prov/efa: Update read nack protocol docs Signed-off-by: Jessie Yang (cherry picked from commit b791d2f7fa98e5adceb04e8a52f6be2c4edf0eda) --- prov/efa/docs/efa_rdm_protocol_v4.md | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/prov/efa/docs/efa_rdm_protocol_v4.md b/prov/efa/docs/efa_rdm_protocol_v4.md index 0fada5145ee..9147b4cea4a 100644 --- a/prov/efa/docs/efa_rdm_protocol_v4.md +++ b/prov/efa/docs/efa_rdm_protocol_v4.md @@ -1497,8 +1497,9 @@ in order to support CQ entry generation in case the sender uses ### 4.7 Long read and runting read nack protocol Long read and runting read protocols in Libfabric 1.20 and above use a nack protocol -when the receiver is unable to register a memory region for the RDMA read operation. -Failure to register the memory region is typically because of a hardware limitation. +when the receiver is unable to register a memory region for the RDMA read operation +or P2P support is unavailable for the RDMA read operation, typically because of a +hardware limitation. Table: 4.2 Format of the READ_NACK packet @@ -1513,12 +1514,14 @@ Table: 4.2 Format of the READ_NACK packet The nack protocols work as follows * Sender has decided to use the long read or runting read protocol -* The receiver receives the RTM packet(s) +* The receiver receives the RTM packet(s) or RTW packet - One LONGREAD_RTM packet in case of long read protocol - Multiple RUNTREAD_RTM packets in case of runting read protocol -* The receiver attempts to register a memory region for the RDMA operation but fails -* After all RTM packets have been processed, the receiver sends a READ_NACK packet to the sender -* The sender then switches to the long CTS protocol and sends a LONGCTS_RTM packet + - One LONGREAD_RTW packet in case of emulated long-read write protocol +* The receiver attempts to register a memory region for the RDMA operation but fails, +or P2P is unavailable for the RDMA operation +* After all RTM/RTW packets have been processed, the receiver sends a READ_NACK packet to the sender +* The sender then switches to the long CTS protocol and sends a LONGCTS_RTM/LONGCTS_RTW packet * The receiver sends a CTS packet and the data transfer continues as in the long CTS protocol The LONGCTS_RTM packet sent in the nack protocol does not contain any application data.