...
RPC retry will be handled in the DAOS client side, DER_BUSY is a retry-able error, client shall re-schedule RPC with hint (0-hint timeout randomly) to resend RPC.
Cart change
high 16 bits of cch_dst_tag will be used for reply hint, a new flag CRT_RPC_FLAG_REJECT will be introduced for interoperability purpose. server will only return hint to client if REJECT flag set on RPC.
and DER_TIMEOUT will return to client so old clients could work with newer servers.(retry without hints)
Protocal Change:
To support NRS, we might extend DAOS RPC to send/reply enough information:
| Code Block |
|---|
struct daos_req_comm_in {
uuid_t req_in_pool_id;
uuid_t req_in_cont_id;
uint32_t req_in_uid;
uint32_t req_in_gid;
uint32_t req_in_projid;
uint64_t req_in_hint; /* for RPC reject */
uint64_t req_in_paddings[4];
crt_phy_addr_t req_in_addr;
d_string_t req_in_jobid;
};
struct daos_req_comm_out {.
uint64_t req_out_hint;
uint64_t req_out_paddings[4];
}; |
This will introduce interoperability issues for involved RPCs, to simplify this a bit, we might just consider object/dtx module.
v2 in/output struct will be introduced for these modules RPC format. modules will negotiate between client and server, then register proper RPC format handler.
In the server side ->dms_get_req_attr will be used extract NRS required attributes from different modules.