Open MPI Development Mailing List Archives

samuel_at_[hidden]

--
Samuel K. Gutierrez
Los Alamos National Laboratory
On Jun 2, 2010, at 10:59 AM, George Bosilca wrote:
> How about ftok ? The init function takes a file_name as argument,  
> and this file name is unique per instance of the shared memory  
> region we want to create. We can use this file name with ftok to  
> create a unique key_t that can be used by shmget to retrieve the  
> shared memory identifier.
>
>  george.
>
> On Jun 2, 2010, at 11:53 , Samuel K. Gutierrez wrote:
>
>> On Jun 2, 2010, at 8:49 AM, Jeff Squyres wrote:
>>
>>> On Jun 2, 2010, at 10:44 AM, George Bosilca wrote:
>>>
>>>>> Not sure what you mean here.  common/sm may create new shmem  
>>>>> segments at any time (e.g., during coll sm).  The RML message  
>>>>> exchange is to ensure that only 1 process creates and  
>>>>> initializes the segment and then all the others just attach to it.
>>>>
>>>> Absolutely not! The RML messaging is not about initializing the  
>>>> shared memory segment. As stated on my original text it has only  
>>>> one purpose: to ensure the file used by mmap is created  
>>>> atomically. The code for Windows do not exchange any RML messages  
>>>> as the function to allocate the shared memory region provided by  
>>>> the OS is atomic (exactly as the sysv one).
>>>
>>> I thought that Sam said that it was important that only 1 process  
>>> shmctl/IPC_RMID...?
>>
>> Hi George,
>>
>> We are using RML messaging in the sysv code to exchange the shared  
>> memory ID (generated by exactly one process).  I'm not sure how we  
>> would go about passing along the shared memory ID without RML, but  
>> any ideas are greatly appreciated.
>>
>> Thanks,
>> --
>> Samuel K. Gutierrez
>> Los Alamos National Laboratory
>>
>>>
>>> -- 
>>> Jeff Squyres
>>> jsquyres_at_[hidden]
>>> For corporate legal information go to:
>>> http://www.cisco.com/web/about/doing_business/legal/cri/
>>>
>>>
>>> _______________________________________________
>>> devel mailing list
>>> devel_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>
>> _______________________________________________
>> devel mailing list
>> devel_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>
>
> _______________________________________________
> devel mailing list
> devel_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/devel