We need the synchronous way for multi-process communication,
i.e., blockingly waiting for reply message when we send a request
to the peer process.
We add two APIs rte_eal_mp_request() and rte_eal_mp_reply() for
such use case. By invoking rte_eal_mp_request(), a request message
is sent out, and then it waits there for a reply message. The caller
can specify the timeout. And the response messages will be collected
and returned so that the caller can decide how to translate them.
The API rte_eal_mp_reply() is always called by an mp action handler.
Here we add another parameter for rte_eal_mp_t so that the action
handler knows which peer address to reply.
sender-process receiver-process
---------------------- ----------------
thread-n
|_rte_eal_mp_request() ----------> mp-thread
|_timedwait() |_process_msg()
|_action()
|_rte_eal_mp_reply()
mp_thread <---------------------|
|_process_msg()
|_signal(send_thread)
thread-m <----------|
|_collect-reply
* A secondary process is only allowed to talk to the primary process.
* If there are multiple secondary processes for the primary process,
it will send request to peer1, collect response from peer1; then
send request to peer2, collect response from peer2, and so on.
* When thread-n is sending request, thread-m of that process can send
request at the same time.
* For pair <action_name, peer>, we guarantee that only one such request
is on the fly.
Suggested-by: Anatoly Burakov <anatoly.burakov@intel.com>
Suggested-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Reviewed-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
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