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

[Bogdan Costescu]

[ This message comes to score-users, as score-info seems to be obsolete, 
based on the automated reply that I've got. ]

Dear SCore developers,

In trying to port the ARMCI communication library to work on PM, we've 
encountered several problems. The documentation and examples did not 
provide satisfactory answers to our questions, so we need to ask for 
clarifications.

Most of the questions are related to low-level PM functions:

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

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 ?

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 ?

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 ?

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 ?

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

We are looking forward for your reply as these are fundamental issues for 
our porting work.

Thank you in advance!

--
Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu ＠ IWR.Uni-Heidelberg.De





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