[SCore-users-jp] Re: [SCore-users] Developing with PM

[Atsushi HORI]

Hi.

I am sorry for this late answer for your query e-mails.

>1. Are the PM functions thread safe ? The documentation only mentions 
>pmCreateAttachFd which has to be protected.

The functions of PM_COMPOSITE are thread safe, I hope. 

>2. How does the send operation (pmSend) works when there is no pmReceive 
>at the other end ? Is it OK to just call one or more times pmSend and then 
>just check if everything was sent with pmIsSendDone ?

pmSend() works asynchronously in some sense. However, when sender 
sends a number of messages, and receiver does not receive at all, 
then the pmSend() returns ENOBUF and fails eventually. So, you are 
right.

>3. ARMCI needs to create a dataserver thread/process which spends 
>lots of time waiting for requests from clients in a select(2) call. I have 
>found an example of using select(2) in "pmest"; is this mechanism still 
>supposed to work ? How to obtain the fd (or fd's) to wait on ? What are 
>the semantics of select(2) when waiting on these fd's: what does it means 
>when select(2) returns a positive integer and FD_ISSET(fd) returns true ? 
>In the dataserver, is one fd enough to signal arrival of messages from any 
>client or we need to have one fd per client ?

Supporting select() is still effective and SCore-D heavily uses. Call 
pmGetFd() function to obtain file descriptors to select.

>4. The pmGetFd function returns a list of fd's associated with the 
>context. What is the meaning/use of having more fd's associated with a 
>context ?

It depends on PM devices. Think about the case having PM on TCP. 
There could be a number of TCP connections and FDs associted with.

>5. The dataserver thread/process has to do its own communication separate 
>from the MPI communication. After calling MPI_Init(), how can another 
>context (to be used for the non-MPI communication) be obtained ? Are there 
>limitations in what this context can do as being the second associated to 
>the process ? How can we obtain the list of nodes associated with the 
>first context and associate it with the second context ?

I will answer in another e-mail.

>6. Is there some more documentation about PM apart from the man pages 
>available with the distribution and from the web site ?

Read the source code :-)

----
Atsushi HORI
Swimmy Software, Inc.

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